Clinical Microbiology Short Essay Question And Answers

Clinical Microbiology Important Notes

1. Sexually transmitted diseases

  • Syphilis
  • Lymphogranuloma
  • Herpes genitalis
  • Gonorrhea
  • AIDS

Clinical Microbiology Short Question And Answers

Question 1. Sore throat

It is an acute tonsilitis and/ or pharyngitis

Sore throat Features:

  • Redness and edema of the mucosa
  • Exudation of tonsils
  • Pseudomembrane formation
  • Edema of uvula
  • Enlargement of cervical lymph nodes

Sore throat Features

Sore throat Causative Organism:

Clinical Microbiology Sore Throat Causative Organism

Question 2. Name the micro-organisms causing meningitis.

Micro-organisms causing meningitis are:

Clinical Microbiology Micro- Organisms Causing Meaningitis

Question 3. Define Bacteraemia and Septicaemia


  • It is defined as the presence of bacteria in blood without any multiplication

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  • It is a condition in which bacteria circulate and actively multiply in the bloodstream

Question 4. Name micro-organisms causing infective endocarditis.

Clinical Microbiology Micro-Organism causing infective endocarditis

Question 5. Name Sexually transmitted diseases

Clinical Microbiology Sexually Transmitted Diseases

Question 6. Stool examination

Stool examination Uses:

  • Stool examination is used to find out ova and cysts

Stool Examination Method:

  • A drop of normal saline is placed at one end of a glass slide and a drop of iodine at the other end
  • A minute of feces is added in both the drops and mixed
  • A coverslip is gently placed over each
  • Examine both under a microscope
  • Any suspicious object if found is studied under high power microscope

Oral Microbiology Short And Long Essay Question And Answers

Oral Microbiology Important Notes

1. Dental plaque consists of

  • Bacteria
  • Epithelial cells
  • Macrophage
  • Leucocytes

2. Factors producing dental caries

  • Host – structure of tooth and nature of saliva
  • Diet – carbohydrate rich diet
  • Time – repeated ingestion of carbohydrate at short interval
  • Microbial flora – Mainly Streptococcus mutans

Oral Microbiology Long Essays

Question 1. Discuss normal oral flora. What is the pathogenesis of dental plaque formation?

Normal Oral Flora:

  • The normal resident oral flora occupies available colonization sites which makes it more difficult for other micro-organisms to become established.
  • At birth, the oral cavity is usually sterile
  • But within a few hours first streptococci gets established followed by other species.
  • Later the oral cavity becomes a mixture of bacteria, fungi, protozoan, and viruses.
  • With the eruption of teeth, these organisms get colonized.
  • Normal oral flora contains the following micro-organisms

Oral Microbiology Normal Oral Flora contains following micro organism

Dental Plaque Formation:

  • Initially, oral bacteria, pellicle, and dietary sucrose are required
  • Pellicle contains salivary glycoprotein while bacteria produce adhesives like glucan from dietary sucrose
  • The first pellicle through its glycoprotein gets adsorbed to the enamel surface and forms a membranous film

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  • Next the glucan produced by the bacteria helps in binding the bacteria to the pellicle
  • As this process continues more and more oral bacteria are adsorbed on the tooth surface
  • As a result of it, layer called dental plaque is formed
  • This later gets calcified to form calculus

Oral Microbiology Short Essays

Question 1. Dental plaque

Dental plaque is a soft non mineralised deposit of bacteria present on the tooth surface and other hard surfaces of the oral cavity

Dental plaque Classification:

Oral Microbiology Dental Plaque Classification

Dental plaque  Composition:

  • Dental plaque consists of
    • Bacteria
    • Epithelial cells
    • Macrophages
    • Leucocytes

Dental plaque  Effects:

  • Calculus formation
  • Dental caries
  • Periodontal diseases

Question 2. Dental caries

  • Dental caries is an infectious, microbiologic disease of the teeth that results in localized dissolution and destruction of the calcified tissues of the teeth.
  • It leads to the weakening of tooth structure, cavity formation, and, eventual loss of tooth

Dental caries Etiology:

  • Four factors interact to produce caries
  • They are as follows:

Oral Microbiology Dental Caries Etiology

Prevention of Dental Caries:

Dental caries can be prevented by

  • Maintenance of good oral hygiene
    • By use of antimicrobials
    • Proper brushing
    • Flossing
    • By scaling at least once in 6 months
  • Control of dietary carbohydrate intake
  • Incorporating fluoride in drinking water
    • This increases resistance to dental caries.

Question 3. Periodontal infection

  • Periodontal infections include diseases of the gingiva, periodontal ligament, cementum, and alveolar bone
  • Initially, the organisms affect the gingiva causing gingivitis
  • Later it progresses to deeper tissues leading to progressive tooth loss

Periodontal infection Etiology:

  • Periodontal microflora, intrinsic factors, and extrinsic factors cause periodontal diseases

Oral Microbiology Periodontal Infection Etiology

Periodontal Diseases:

Oral Microbiology Periodontal Diseases


Oral Microbiology Short Question And Answers

Question 1. Microbiology or bacteria causing dental caries

Bacteria that cause dental caries are

Oral Microbiology Bacteria Causing Dental Caries

Question 2. Normal flora of the respiratory tract

Oral Microbiology Normal flora of respiratory tract

Question 3. Name micro-organisms causing a periapical abscess

Micro-organisms causing periapical abscesses are:

Oral Microbiology Micro-Organisms causing periapical abscess

Question 4. Oral antiseptics

  • Oral antiseptics re used to keep the commensal bacterial flora of the oral cavity clean
  • Some of them act as a deodorant

Oral antiseptics Example:

  • Thymol
  • Menthol
  • Eugenol
  • Benzoic acid
  • Boric acid
  • Calcium
  • Magnesium peroxide.

Helminths Virology Question And Answers

Helminths Long Question And Answers

Question 1. Describe the life cycle of ankylostoma duodenal. Write a note on pathogenicity and laboratory diagnosis of Ankylostomiasis

The common name of ancylostoma duodenal is the old-world hookworm

Ankylostoma duodunale Life Cycle:

  • Man is the only definitive host
  • It involves following the steps

Helminths Ankylostoma duodunale Life Cycle

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Helminths Life cycle of Hookworm

Ankylostomiasis Pathogenicity:

  • Migrating larvae may cause three types of lesions as follows

Helminths Migranting larvae may cause three type of lesions

  • The worm causes hookworm disease in man

Ankylostomiasis’s Clinical features are:

  • Microcytic, hypochromic anemia
  • Epigastric pain
  • Dyspepsia
  • Vomiting
  • Diarrhea

Ankylostomiasis Laboratory Diagnosis:

1. Direct methods:

Helminths Direct method

2. Indirect methods:

Helminths Indirect method

Question 2. Enumerate the common tapeworms. Describe the morphology, life cycle, and laboratory diagnosis of taeniasolium


  • Taenia saginata
  • Taeniasolium
  • Echinococcus granulosus

Taenia Solium Morphology:

Helminths Taenia Solium Morphology


Taenia Solium Life Cycle:

  • The worm passes its life cycle in two hosts: the definitive host, man, and an intermediate host, pig
  • The adult worm lives in the small intestine of man
  • Eggs are passed out with the feces
  • The animal swallows these eggs and gets infected
  • Oncosphere hatches out
  • It penetrates the gut wall
  • Carried in the systemic circulation
  • The naked Oncospheres are transformed into cysticercus cellulose in the muscle
  • By intake of uncooked or partially cooked pork, enters into the alimentary canal of man
  • The scolex of cysticercus evaginates and attaches to the gut wall
  • It develops into an adult worm

Helminths Life cycle of Taenia Sp.

Taenia Solium Laboratory Diagnosis

1. Stool examination

  • It detects eggs of T. solium

Diagnosis of cysticercosis

2. Diagnosis of cysticercosis

  • It is done by
    • Biopsy examination of subcutaneous nodules
    • X-ray of skull and soft tissues
    • CT scan of the brain
    • Eosinophilia

Helminths Virology Question And Answers

Question 3. Describe the morphology, life cycle, and pathogenesis of the Wuchereria branchfti. Discuss the diagnosis of filariasis.

Wuchereria Branchfti Morphology:

1. Adult worms

  • They are transparent, long hair-like structures
  • Color-Creamy white
  • Shape- Filiform with tapering ends

Helminths Wuchereria branchfti Morphology in Adult WormsHelminths Wuchereria branchfti Morphology in Adult Worms

  • Both remain coiled together
  • Life span- 5-10 years

2. Embryos

  • Color- colorless
  • It is transparent
  • Heads and tails- Heads are blunt while tails are pointed
  • Size- 290 micrometer * 6-7 micrometer
  • Covered by hyaline sheath
  • Nuclei appear as granules

Helminths Microfilaria of Wuchereria boncrofti

Wuchereria Branchfti Life Cycle:

  • Wuchereria bancrofti passes its life cycle in man and mosquito
  • Adult worms are present in the lymphatics system of man
  • Male fertilises female
  • Embryos or microfilariae are discharges
  • These reach bloodstream
  • Microfilariae are taken up by mosquitoes during a blood meal
  • It develops in mosquito
  • Through the bite of mosquito, the infective larvae are deposited on the skin
  • This penetrates the skin and reaches the lymphatic channels
  • Gets settled in lymph nodes
  • Develops into an adult worm
  • Again fertilization occurs and the cycle is repeated

Helminths Life cycle of Wuchereria Bancrofti

Wuchereria Branchfti Pathogenesis:

  • W. bancrofti causes filariasis

Wuchereria Branchfti Types:

Helminths Wuchereria branchfti Types

Diagnosis Of Filariasis:

1. Direct methods

  • Samples collected are
    • Blood
    • Chylous urine
    • Exudate of lymph varix
    • Hydrocele fluid
  • Blood film should be made in night between 10 pm to 2 am as the number of microfilariae is more at night

2. Indirect methods

  • It includes
  • Blood examination- Detects Eosinophilia
  • Serological tests like ELISA, indirect fluorescent antibody, and indirect haemagglutination assay.

Helminths Short Question And Answers

Question 1. Hydatid cyst:

  • The cyst wall secreted by the embryo
  • It consists of the following.
  1. Ectocyst
  2. Endocyst

1. Ectocyst:

  • It is a hyaline membrane which form thick, tough outer circular layer and is elastic in nature.
    • When incised it curls on itself
  • As a result, it exposes the inner layer

2. Endocyst:

  • It is inner (or) germinal layer
  • It forms an ectocyst on outer side
  • It gives rise to brood capsules and scolices on inner side.

Hydatid fluid:

  • It is secreted by endocyst.

Hydatid cyst Characteristics:

  • It is clear, colourless (or) pale yellow fluid.
  • It is a slightly acidic nature
  • It is highly toxic, when absorbed it gives rise to anaphylactic symptoms.
  • Due to its antigenic nature it is used for Casoni’s test.
  • It has a low specific gravity
  • Composition- It contains
    • Sodium chloride
    • Sodium sulfate
    • Sodium phosphate
    • Sodium and calcium salts of succinic acid

Hydatid sand:

  • It is a granular deposit which consists of brood capsules, free scolices, and loose hooklets.
  • It gets settled at the bottom of the hydatid cyst

Question 2. cassoni’s test

It is an immediate hypersensitivity skin test introduced by Casoni in 1911.

Cassoni’s test Method:

  • Sterile hydatid fluid is used as an antigen.
  • Hydatid fluid is obtained from hydatid cyst from humans or animals
  • It is made of sterile
  • Now 0.2 ml of it is injected intradermally in one arm
  • While 0.2 ml of normal saline is injected intradermally in the other arm

Cassoni’s test Result:

  • It produces a large wheal measuring 5 cm in diameter or more within 30 minutes in all positive cases.
  • Also shows multiple pseudopodia.

Question 3. Microfilaria

  • Microfilariae are the larvae of nematodes.
  • The female nematodes are viviparous giving birth to larvae called microfilariae.
  • It needs two hosts to complete its life cycle man and a blood-sucking insect

Microfilaria Features:

Helminths Microfilaria Features

Question 5. Cysticercus Ceilulosae

  • Cysticercus cellulose is the larval stage of taenia solium
  • It develops in the muscles of the pig which is an intermediate host
  • A mature cyst is an opalescent ellipsoidal body and the long axis of the cyst is parallel to the muscle fiber.
  • A dense milky white spot is present at the side where the scolex with its hooks and suckers remains invaginated.
  • The cyst develops further when ingested by man which is the definitive host
  • It may develop in any organ but are usually present in the subcutaneous tissues and muscles.

Various features of cysticercosis.

  • They cause palpable nodule in sub-cutaneous tissues and muscles
  • In the brain leads to epileptic attacks.
  • Neurocysticercosis involving the nervous system is the most serious form

Question 6. Diagram of Fertilised egg of ascaris lumbricoides

Helminths Eggs of Ascaris lumbricoides

Question 7. Life cycle of Ascaris lumbricoides

  • Ascaris lumbricoides passes its life cycle in only one host i.e. Man
  • Adult worms reside in the jejunum of man
  • The passing of Fertilised eggs containing the unsegmented ovale in the feces
  • These develop in soil
  • Rhabditiform larva develops from the unsegmented ovum
  • This undergoes first molting
  • Intake of food, drink or raw vegetables contaminated with eggs containing Rhabditiform larvae causes infection in man
  • Liberation of Rhabditiform larvae occurs in the upper part of the small intestine
  • They burrow through the mucous membrane of the small intestine
  • It is carried to the liver and then enter pulmonary circulation
  • They reach lungs and enlarge
  • They break through the capillary wall and reach alveoli
  • The larvae reach the bronchi, then the trachea and are swallowed after reaching the pharynx
  • Pass down to esophagus, stomach and then gets localized in the upper part of the small intestine
  • Here another molting occurs and the larvae grow into an adult worm
  • Thus the cycle repeats

Helminths Life cycle of Roundworm

Question 8. Larva migrans

It is a condition caused by ingestion of embryonated eggs of some nematodes parasitizing animals

Larva migrans Pathogenesis:

  • Larvae are hatched in the small intestine
  • These reach extraintestinal sites
  • Gets settled in the liver, lungs, and other organs
  • This leads to the formation of granulomatous lesions

Larva migrans Clinical Features:

  • Leucocytosis
  • Eosinophilia

Larva migrans Diagnosis:

  • Serological tests detect antibodies in serum

Larva migrans Prevention:

  • Deworming animals prevent this disease

Question 9. Name four tapeworms.

  • Taeniasolium
  • Taeniasaginata
  • Echinococcusgranulosus
  • Diphyllobothrium latum
  • Hymenolepsis nana

Protozoans Virology Short And Long Essay Question And Answers

Protozoans Important Notes

1. Entamoeba histolytica

  • Occurs in three forms
    • Trophozoites
    • Pre cystic stage
    • Cyst
      • It passes its life cycle only in man
      • Diseases caused by it
        • Intestinal amoebiasis
        • Extra intestinal amoebiasis
          • Other Entamoeba are
            • Entamoeba coli
            • Entamoeba gingivalis

2. Species of Plasmodium

  • Pvivax
  • P falciparum
  • P malariae
  • P ovale

3. Stages of the life cycle of Plasmodium

  • Pre erythrocytic schizogony
  • Erythrocytic schizogony
  • Gametogony
  • Exo erythrocytic schizogony

4. Malarial pigment

  • Yellowish brown – P. vivax
  • Dark brown – P.falciparum, P.malariae
  • Dark yellowish brown- P.ovale

5. Malaria

  • Clinical features
    • Febrile paroxysm
    • Anaemia
    • Splenomegaly
  • Complications
    • Pernicious malaria
    • Black water fever

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6. Cestodes

  • Taenia saginata
  • Taenia solium

7. Nematodes

  • Ascaris lumbricoides or round worm
  • Hookworm
    • Ankylostoma duodenale
    • Wuchereria bancrofti

Protozoans Long Essays

Question 1. Describe the morphology, pathogenesis, and life cycle of Entamoeba histolytica. Write about laboratory diagnosis of intestinal amoebiasis.

Entamoeba histolytica causes intestinal amoebiasis and hepatic amoebiasis

Entamoeba histolytica Morphology:

The parasite exists in 3 forms

Protozoans Parasite exists in 3 forms

Entamoeba histolytica Life Cycle:

  • E. histolytica passes its life cycle in only one host, the man.
  • The mature quadranucleate cysts are infective forms.
  • These cysts enter in to men through ingestion of water and food containing it
  • These reach the caecum or lower part of the ileum called excystation
  • Each mature cyst liberates tetranuclear amoeba
  • Forms eight meta cystic Trophozoites by binary fission
  • It gets lodged in the submucous tissue of the large intestine
  • E.histolytica secretes a proteolytic enzyme
  • Causes destruction and necrosis of tissues
  • Results in the formation of flask-shaped ulcers
  • Next, these Trophozoites are
    • Excreted along with blood and mucous in feces
    • Results in amoebic dys­entery
    • Enter into deeper layers
    • Enter into the portal vein
    • Reaches liver
    • Forms amoebic hepatitis and amoebic liver abscess
  • Effect of the parasite on the host decreases
  • This increases host tolerance and healing starts
  • Encystation occurs which is the transformation of Trophozoites into cysts and cysts.

Protozoans Life cycle of Entamoeba histolytica

Entamoeba histolytica Pathogenesis:

E. Histolytica can cause two types of pathological lesions as follows

1. Primary (or) Intestinal Amoebiasis:

Protozoans Primary or Intestinal Amoebiasis

  • This condition is called as amoebic dysentery.
  • This ulcer maybe generalized (or) may be localized to the ileocaecal (or) sigmoidorectal region.
  • Occasionally ulcers may involve deeper tissues and may cause perforation (or) peritonitis.
  • Erosion of blood vessels may lead to hemorrhage.
  • The superficial lesions generally heal without scar¬ring.
  • Deep ulcers form scars leading to strictures, partial obstruction, and thickening of the gut wall

2. Extra-intestinal amoebiasis [or) secondary (or) metastatic lesions.

  • Amoebic liver abscess:

Protozoans Amoebic liver abscess

Laboratory Diagnosis of Intestinal Amoebiasis:

1. Stool examination:

  • The stool is collected directly into a wide-mouthed con¬tainer and examined without delay.
    • Macroscopic Examination
      • The stool is an offensive odor
      • Dark brown and semifluid
      • Acid in reaction
      • Mixed with blood and mucous
    • Microscopic Examination
      • The cellular exudates is scanty, and consist of nuclear masses of a few pus cells, macrophages, and epithelial cells
      • RBCs are seen in clumps
      • Charcot- Leyden crystals are also seen

2. Blood Examination

  • In early cases, it is always negative
  • The antibody can be detected in later stages of invasive intestinal amoebiasis
  • The test used is ELISA haemagglutination assay (HIA).

3. DNA Probes:

  • DNA probes have been used to detect E. histolytica in stool specimens.

Question 2. Describe the life cycle of malarial parasites in man. Give a brief description of pathological lesions produced in man.

Malaria is a disease caused by four plasmodium species which are as follows:

  • P. vivax
  • P. Falciparum
  • P. Malaria
  • P. Ovale.

Malarial Life Cycle:

The malarial parasites pass their life cycle in two. hosts.

  1. Man intermediate host [a sexual development]
  2. Female anopheles mosquito – definitive host [sexual development].

Human cycle or schizogony or a sexual cycle:

  • The sporozoite is the infective form of a malarial parasite.
  • Man gets infected by the bite of the infected female Anopheles mosquito
  • This mosquito contains sporozoites in the salivary gland which enter directly into the blood circulation of man
  • By this human cycle starts which comprises of following stages.

1. Pre-erythrocytic schizogony

  • It is a developmental phase of sporozoites inside the liver cells
  • The shape of sporozoites- Round
  • Size-Varies
  • They undergo nuclear division to develop schizont
  • Each schizont contains 20,000-50,000 merozoites
  • Duration of this stage
    • P. vivax           – 8 days
    • P. falciparum  – 6 days .
    • P. malariae     – 13-16 days
    • P. ovale          –  9 days
  • After this period, the liver cells rupture
  • As a result, merozoites are released into the bloodstream

2. Erythrocytic schizogony:

  • Release of merozoites into the blood
  • Penetration of it into RBCs
  • Rupture of RBCs which leaves behind a residue of hemoglobin pigment called hemozoin
  • Release of merozoites
  • These attack new RBCs
  • Thus the cycle continues

3. Gametogony:

  • Some merozoites develop sexual forms known as microgametocytes and macro gametocytes

Protozoans Microgametocytes And Macrogametocytes

4. Exo-erythrocytic schizogony:

  • Some sporozoites enter liver cells but don’t multi-ply
  • Enter in the resting phase and are known as Hypno- zoite
  • These hypnozoites get reactivated
  • Forms schizonts
  • Releases merozoites called phanerozoic
  • Attack RBCs
  • Causes relapse of malaria

Protozoans Life cycle of Malarial parasite

Malaria Clinical Features:

  • Intermittent fever which is named as malaria is caused by plasmodium
  • It consists of

1. Febrile paroxysm

  • It comprises of three stages

Protozoans Febrile paroxysm

2. Anaemia

  • Microcytic or normocytic hypochromic anemia develops

3. Spenomegaly.

  • The spleen becomes enlarged and palpable
  • Black water fever, and pernicious malaria are the most commonly seen complications in falciparum malaria.

Protozoans Short Essays

Question 1. Laboratory diagnosis of extraintestinal amoe¬biasis

Diagnostic methods for extraintestinal amoebiasis are as follows

Protozoans Diagnostic methods for extraintestinal amoebiasis

Question 2. Leishmania donovani

It causes visceral leishmaniasis or kala-azar

Leishmania donovani Morphology:

It occurs in two forms:

Protozoans Leishmania donoval Morphology

Protozoans Amastigote and promastigote forms of leishmania donovani

Leishmania donovani Life Cycle:

  • The parasite has two stages in its life cycle
    • Amastigote form
    • Promastigote form
  • Initially, multiplication of amastigote form occurs in the reticuloendothelial cells in the host
  • Enlargement of host cells occurs
  • These cells rupture to release parasites into circulation
  • Blood-sucking insect obtains it by sucking
  • Development of Promastigote form from Amastigote form

Protozoans Life Cycle Of Leishmania Donovani

Leishmania donovani Clinical Features:

  • Pyrexia
  • Splenomegaly
  • Hepatomegaly
  • Lymphadenopathy
  • Anaemia

Question 3. The life cycle of plasmodium in mosquito

  • The sexual development of plasmodium occurs in mosquito
  • It starts in the human host by the formation of Gametocytes
  • The cycle includes the following steps
  • Bite of female anopheles from the patient
  • Mature sexual forms develop in the mosquito
  • In the midgut
  • 1 microgametocytes- develops 4-8 microgametes
  • 1 macrogametocyte- Develops 1 macrogamete
  • Fertilization of macrogamete occurs
  • Formation of zygote
  • Lengthening and maturation of zygote to form ookinete
  • Formation of oocyst from ookinete
  • Maturation of oocyst
  • Increase in size and number of sporozoites
  • Rupture of oocyst to release sporozoites in the body of the mosquito
  • Distribution of sporozoites into various organs and tissues especially in salivary glands

Question 4. Laboratory diagnosis of malaria

The demonstration of the parasite in the blood is the most important method for the diagnosis of malaria.

1. Microscopic examination of blood film:

  • Thick and thin smears of blood are prepared on the same slide (or) two different slides.
  • Blood is collected prior to antimalarial therapy

Protozoans Microscopic examination of blood film

2. Fluorescent microscopy:

  • A blood smear is prepared on a slide and is stained with acridine orange
  • The slide is observed under a fluorescent microscope.
  • The nuclear DNA of the malarial parasite is stained green and cytoplasmic RNA is stained red.

3. Blood counts:

  • Blood shows moderate leukopenia and monocytosis.

4. Serological tests:

  • Serological tests used are
    • ELISA
    • Indirect haemagglutination assay
    • Indirect immunofluorescence test.

5. DNA probes:

  • These are sensitive and specific diagnostic methods for the diagnosis of malaria
  • It can detect even a low parasitemia i.e., <10 parasites/dl

6. Polymerase chain reaction (PCR):

  • It can also be used.

7. Rapid diagnostic tests:

  • These are based on the detection of antigens using immune chromatographic methods.
  • In these tests, a dipstick containing monoclonal antibodies is directed against the parasitic antigens.
  • This test takes about 15 minutes.
  • Several commercial kits are available.
  • Kits available detect histidine-rich protein (HRP – II) of P. falciparum.
  • The test is commercially available as the parasite ‘F’ test.

Question 5. Complications of plasmodium falciparum infection?

Complications of P.Falciparum are:

  1. Pernicious malaria
  2. Black water fever.

1. Pernicious malaria:

  • It is life-threatening condition

Pernicious malaria Cause:

  • It is due to heavy parasitization.

Pernicious Malaria Clinical Features:

  • It is grouped into the following:

Protozoans Pernicious malaria clinical features

2. Blackwater fever:

Occurs in persons who are previously infected and had inadequate doses of quinine

Black water fever Clinical Features:

  • Intravascular hemolysis,
  • Fever,
  • Haemoglobinuria
  • Vomiting and prostration with the passage of dark red (or) blackish urine hence called backwater fever.

Black water fever Mechanism:

  • An autoimmune mechanism may be involved in hemolysis
  • Parasitized erythrocytes during previous infection act as antigen
  • Antibodies are formed against it
  • Due to this antigen-antibody reaction, massive destruction of erythrocytes occurs
  • There is excessive deposition of haemosiderin pigment in the liver, spleen, and kidneys.
  • Sequel of black water fever include
    • Circulatory failure
    • Renal failure,
    • Liver failure,
    • Anaemia.

Protozoans Short Question And Answers

Question 1. Draw morphological forms of Entamoeba His¬tolytica

Protozoans Different morphological of Entamoeba histolytica

Question 2. Amoebic dysentery

  • Amoebic dysentery is also known as intestinal amoebiasis
  • It is a condition in which the infection is confined to the intestine and is characterized by the passage of blood and mucus in the stool

Amoebic dysentery Types:

1. Acute amoebic dysentery

  • Multiple ulcers occur
  • These ulcers are deep and extensive
  • Its complications are
    • Pericaecal and pericolic abscess
    • Amoebic appendicitis
    • Perforation
    • Generalized peritonitis
    • Gangrene of guts
    • Fistula

2. Chronic amoebic dyssentery

  • A single latent ulcer is present in the caecum while multiple small superficial ulcers are scattered throughout the large intestine
  • Stricture formation occurs
  • Amoeboma in the caecum and large intestine develops

Question 3. E.gingivalis / Morphology of E.gingivalis

E.gingivalis Morphology:

  • It is a small amoeba measuring 10 – 20 (m in diameter and is actively motile by multiple pseudopodia.
  • It has the only trophozoite stage and there is no cystic phase.
  • It contains
    • The cytoplasm which is divided into clear ectoplasm and granular endoplasm.
    • Cytoplasmic inclusions consisting of bacteria leucocytes but never RBCs
    • Nucleus is spherical
    • Central karyosome.
    • Nuclear membrane lined with closely packed chromatin granules.

E.gingivalis Pathogenesis:

  • E.gingivalis is a parasite of human mouth.
  • It occurs as a commensal in gingival tissue around the teeth particularly in the unhealthy tissues such as in pyorrhoea alveolaris.
  • It is also found in the crypts and histologic sections of diseased tonsils.
  • It is transmitted by close contact like kissing.
  • Laboratory diagnosis depends on the demonstration of tro¬phozoites of E. Gingivalis in the material removed from the gingival margin of the gum (or) from the denture.

Question 4. Erythrocytic schizogony

  • It is the second stage of the human cycle of the malaria parasite
  • During this phase, the parasite resides inside RBC and passes through stages of Trophozoites, schizonts, and merozoites.
  • Following changes occur during this phase
  • Release of merozoites into the blood

Protozoans Erythrocytic Schizogony

Question 6. Plasmodium falciparum

Plasmodium falciparum is one of the malarial parasites

Stages of Human Cycle in P. Falciparum:

Protozoans Stages of Cycle in P. Falciparum

Protozoans Gametocytes of plasmodium species

  • P. falciparum is the most pathogenic among the plasmodium species infecting man
  • No relapse occurs in P.falciparum infection
  • It invades erythrocytes of all ages
  • The incubation period of it is 10-14 days


  • Pernicious malaria
  • Black water fever

Question. Black water fever

Occurs in persons who are previously infected and had inadequate doses of quinine

Black water fever Clinical Features:

  • Intravascular hemolysis,
  • Fever,
  • Haemoglobinuria
  • Vomiting and prostration with the passage of dark red (or) blackish urine hence called backwater fever.

Question 9. Kala-azar

Leishmania denovani produces the disease Salazar (or) visceral leishmaniasis.

Kala-azar Clinical Features:

  • Pyrexia,
  • Splenomegaly,
  • Hepatomegaly,
  • Lymphadenopathy and
  • Anaemia.

Kala-azar Laboratory Diagnosis:

1. Direct evidence:

Protozoans Direct evidences

2. Indirect evidence:

Protozoans Indirect evidences

3. Rapid immune chromatographic strip test:

  • It detects antibodies against the K39 antigen of L. donovani
  • It indicates active kala-azar

Question 10. Benign tertian malaria

  • Benign tertian malaria is caused by Plasmodium vivax
  • Initially, there may be continuous or remittent fever
  • In later stages, typical intermittent periodic fever develops
  • Initially, two broods of parasites undergo schizogony on alternate days but then one brood drops out.

Question 11. Mention the parasites found in peripheral blood smear.

Protozoans Peripheral blood smear

Mycology Virology Short And Long Essay Question And Answers

Mycology Important Notes

1. Classification of fungi

  • Phycomycetes or zygomycetes
  • Ascomycetes
  • Basidiomycetes
  • Fungi imperfect

2. Types of spores.

  • Sexual spores – oospore, ascospore, zygospore and basidospore
  • Vegetative or asexual spore- blastospore, arthrospores, chlamydospores

3. Lab diagnosis used for fungal infection

  • KOH mounts
  • Wood’s lamp
  • Sabouraud’s glucose agar and cornmeal agar culture media
  • Microscopic examination

4. Types of hair infection

  • Endothrix
  • Ectothrix

5. Candidiasis

  • Causative agent – Candida albicans
  • Classification
  • Acute
    • Pseudomembranous
    • Acute atrophic
  • Chronic
    • Chronic hyperplastic
    • Chronic atrophic
  • Complications
    • Intestinal Candidiasis
    • Bronchopulmonary Candidiasis
    • Septicemia
    • Endocarditis
    • Meningitis

Read And Learn More: Microbiology Question and Answers

6. Aspergillosis

  • It is the most opportunistic pathogen
  • Caused by inhalation
  • Diseases caused by it are
    • Aspergillus asthma
    • Bronchopulmonary aspergillosis
    • Colonizing aspergillosis
    • Invasive or disseminated aspergillosis
    • Superficial infections

Mycology Long Essays

Question 1. Give an account of infections caused by Can¬dida albicans. Describe the laboratory diagnosis of Candida.

Infections Caused by Candida:

Lesions caused by Candida are as follows.

Mycology Infections Caused By Candida

1. Oral thrush Features:

  • The lesions appear soft, white, and slightly elevated plaques
  • Sites:
    • Buccal mucosa
    • Tongue
    • Gingiva
    • Palate
    • The floor of the mouth
    • The entire oral cavity is involved in severe cases
  • Person affected are
    • HIV patients
    • Cancer patients undergoing chemotherapy or radiotherapy
    • Neonates and infants
    • Debilitated and chronically ill patients

2. Chronic oral candidiasis

  • Caused by denture-induced stomatitis or chronic hypertrophic candidiasis

Mycology Chronic Oral Candidiasis

3. Chronic mucocutaneous candidiasis

  • Integral lesions are similar to other types
  • Extraoral lesions involve skin, nails, and mucous

4. Angular stomatitis

  • Effects lips
  • Common in immunocompromised patients

5. Circumoral candidal dermatitis

  • Involves lips and area around lips

Candida Laboratory diagnosis:

1. Direct microscopy:

  • Gram-stained smears and KOH mounts from le¬sions of skin, nail (or) mucous membrane are used
  • These show budding Gram-positive yeast cells.

2. Culture:

  • Sabouraud’s dextrose agar media (SDA)
    • SDA is inoculated and incubated at 25 – 37° C for 24 hours.
    • Cream-coloured smooth pasty colonies appear.
    • On gram staining of it shows gram positive bud¬ding yeast cells.

3. Identification:

Candida albicans can be identified by

  • Germ tube test:
    • When incubated in human serum at 37oC, C. al-beans form germ tubes within two hours. – This is called Reynolds braude phenomenon
  • Chlamydospores.
    • Chlamydospores develop in cornmeal agar at; 20 degrees C.

Mycology Germ tube formation

4. Biochemical reactions:

  • C. albicans can be identified by the assimilation and fermentation of sugar.

5. Serology: 

  • C. Albicans can also be identified by the precipita¬tion test with a carbohydrate extract of group A an¬tigens.

Mycology Short Essays

Question 1. Mycetoma/Madhura foot.

  • Mycetoma is a chronic granulomatous infection of the subcutaneous tissue
  • It usually affects the foot but rarely even other parts of the body
  • Commonly seen in tropical countries.

Mycetoma Synonyms:

  • Madhura foot as it was first described from Madurai South India.
  • Madhuramycosis.

Mycetoma Etiology:

Causative agents are

  • Eumycetoma
    • Madhuvella mycetomi
    • Acremonium falciforme.
    • Actinomycetoma.
  • Actinomadura Madurai
    • Nocardia
    • Streptomyces.

Mycetoma Pathogenesis:

Mycology Candida pathogenesis

Mycetoma Treatment:

Mycology Causative organism treatment

Question 2. Actinomycosis.

It is a chronic granulomatous disease

Actinomycosis Causative Organism:

Mycology Actinomycosis Causative Organism

Actinomycosis Forms:

Mycology Actinomycosis Forms

Actinomycosis Features:

It is characterized by

  • Multiple abscesses
  • Tissue destruction
  • Fibrosis
  • Formation of multiple sinuses
  • Painless indurated swelling
    • It may cause gingivitis and periodontitis

Actinomycosis Diagnosis:

1. Microscopy

  • Steps
    • Dilute the pus with saline in a test tube
    • Allow it to settle
    • Sulfur granules are obtained from it
    • These granules are crushed between slides
    • Smears are prepared
    • One of them is Gram stained and the other is acid-fast stained
    • Observe these smears
  • Observations
    • Gram-stained smear shows Gram-positive filaments surrounded by peripheral radiating Gram-negative clubs
    • This results in a sun-ray appearance
    • Acid-fast smears show the central part of non-acid fast clubs surrounded by acid-fast clubs

2. Culture

Cultural media used are

  • Thioglycollate broth
  • Brain heart infusion agar
  • Blood agar
    • They are incubated anaerobically and aerobically with 5% CO2 at 37 degrees C for 2 weeks
    • It results in spider colonies

Actinomycosis Treatment:

  • It involves surgical removal of affected part
  • The antibiotic used in such cases is penicillin

Question 3. Pathogenesis of Candida albicans.

  • Candidiasis is an opportunistic endogenous infection
  • Predisposing factors are:
    • Diabetes
    • Immunodeficiency
    • Malignancy
    • Prolonged administration of antibiotics
    • Patients on immunosuppressive drugs and intra¬venous catheters
  • Lesions caused by it:

Mycology Short Question And Answers

Question 1. Ray fungus

  • Actinomyces are known as ray fungus
  • They are
    • Gram-positive
    • Non-motile
    • Non-sporing
    • Non arid fast organism
  • They appear as granules in the pus.
  • When these granules are crushed between two slides and Gram stained, they show a central filamentous mycelium surrounded by a peripheral zone of swollen radiating club-shaped structures
  • This gives it a sun-ray appearance
  • They cause actinomycosis

Question 2. Rhinosporidiasis.

Rhinosporidiosis is a chronic granulomatous disease.

Rhinosporidiasis Causative Organism:

  • Rhinosporidium seeberi.

Rhinosporidiasis Mode of Infection:

  • Frequent contact with stagnantwater.

Rhinosporidiosis Features:

  • Friable polyps
  • Sites involved- nose, mouth, and eye
  • Oral manifestations are Oropharyngeal lesions
  • They appear as soft red polypoid growth and spread to the pharynx and larynx.
  • These lesions contains mucoid discharge and are vascular.

Rhinosporidiosis Diagnosis:

  • H and E stained tissue sections show a large number of endospores within the sporangia
  • These are embedded in a stroma of connective tissue, and capillaries

Question 3. Cryptococcosis?

It is caused by a Cryptococcus neoformans, a capsu- lated yeast

Cryptococcosis Morphology:

  • A spherical budding cell having a prominent polysaccharide capsule.
  • It is a true yeast and gram-positive.

Cryptococcosis Pathogenesis:

  • Occurs through inhalation

Mycology Cryptococcosis pathogenesis

Sites Involved:

  • Skin
  • Lymph nodes
  • Bones
  • Cutaneous lesions characterized by small ulcers to large granuloma

Laboratory diagnosis:

  • Laboratory diagnosis is done by direct microscopy, culture, latex agglutination test, and animal inoculation test

Question 4. Aspergillosis?

Aspergillosis Etiology:

  • Aspergillosis is caused by inhalation of aspergillus co- nidia (or) mycelia fragments which are present on the decaying matter, soil (or) air.

Aspergillosis Forms:

3 clinical forms of aspergillosis are

Mycology Clinical forms of aspergillosis

Aspergillosis Laboratory Diagnosis:

  • KOH smears show non-pigmented septate hyphae with characteristic dichotomous branching.


  • The clinical specimen is inoculated on SDA without cycloheximide and incubated at 25oC.
  • Colonies appear within 2 days


  • It shows a velvety to powder surface and are colored.

Mycology Colonies

Question 5. Name three opportunistic fungi.

  • Some saprophytic fungi usually do not produce disease but may cause infection under special conditions such as immune-compromised individuals and terminal stages of chronic disease.
  • These are called as opportunistic fungi.

Examples are:

Mycology Fungi Examples

Predisposing conditions:

  • Widespread use of antibiotics, corticosteroids
  • Immunosuppressive drugs
  • Immunosuppressive diseases like AIDS.

Question 6. Mention two important media for culturing fungi.

  • Sabouraud’s dextrose agar (SDA)
  • SDA medium with antibiotics
  • Brain heart infusion (BHI) agar with blood and antibiotics.
    • Fungi are incubated at 37 degrees C and 25 degrees C for 3 weeks in SDA medium
    • Chloramphenicol is added in the culture medium to suppress the growth of contaminating bacteria while cyloheximide is incorporated to suppress the contaminating fungi.

Question 7. Fungus affecting hair

  • Dermatophytes are the group of fungi affecting hair.
  • Favus is a chronic type of ringworm involving the hair follicles

Fungus affecting hair Features:

  • Alopecia
  • Scarring
  • Sparse hyphal growth
  • Formation of air spaces within the hair shaft

Fungus affecting hair Types:

Mycology Fungus affecting hair types

Mycology Ectothrix and endothrix

Question 8. A quick method of diagnosing Cryptococcus neoformans.

  • The latex agglutination test is a quick method for diagnosing Cryptococcus neoformans
  • In this test, polystyrene latex particles are employed to absorb the antigen
  • Latex agglutination tile is used in it
  • The antigen detected is Cryptococcal capsular polysaccharide antigen
  • The specimen used is CSF, serum or urine.

Question 9. Mention two oral fungal infections

  • Oral fungal infections are:
    • Rhinosporidiosis
    • Sporotrichosis
    • Histoplasmosis
    • Blastomycosis
    • Candidiasis

Retrovirus HIV Virology Short And Long Essay Question And Answers

Retrovirus HIV Important Notes

1. HIV

  • Mode of transmission
    • Sexual intercourse
    • Blood and blood products
    • Tissue and organ donation
    • Injections and injuries
    • Mother to baby
  • Clinical features
    • Low-grade fever
    • Malaise
    • Headache
    • Lymphadenopathy
    • Spontaneous resolution within weeks
    • Seroconversion illness at 3 to 6 weeks
  • Diagnosis
    • Screening test – ELISA test
    • Confirmatory test – Western blot test, polymerase chain reaction

Retrovirus HIV Short Essays

Question 1. HIV virus

HIV occurs in two main types,

  1. HIV-1
  2. HIV-2

HIV virus Morphology:

  • HIV is a spherical-enveloped virus
  • Size: 90-120 nm in diameter
  • It contains
    • Two identical copies of single-stranded RNA genome
    • Reverse transcriptase enzyme
    • Nucleocapsid surrounding the core
    • Lipoprotein envelope
    • Projecting spikes on the surface
    • Anchoring transmembrane pedicles

Retrovirus HIV Structure of Human Immunodeficiency virus

Read And Learn More: Microbiology Question and Answers

HIV virus Modes of Transmission:

There are three modes of transmission

  1. Sexual contact
  2. Parenteral transmission
  3. Perinatal transmission

HIV virus Clinical Features:

It is classified into various groups by the Center for Disease Control in Atlanta, USA

  1. Group 1- Acute HIV infection
  2. Group 2 – Asymptomatic infection
  3. Group 3- Persistent generalized lymphadenopathy
  4. Group 4- Symptomatic HIV infection

HIV virus Oral Manifestations:

  • Greater risk for bacterial, viral, and fungal infections
  • Dental caries
  • Gingivitis
  • Acute necrotizing ulcerative gingivitis
  • Herpes Simplex infections
  • Hairy leukoplakia
  • Candidiasis

HIV virus Diagnosis:

  • Immunological tests:
    • Total leucocyte count
    • Lymphocytes count
    • T cell subset assays
    • Platelet count
    • Raised IgG and IgA levels
    • Diminished CM1
    • Lymph node biopsy
  • Specific Tests:
    • Antigen detection
    • Virus Isolation
    • Polymerase chain reaction
    • Antibody detection

HIV virus Screening Tests:

  • ELISA test
  • Karpastest
  • Rapid tests
  • Indirect immunofluorescence

HIV virus Confirmatory Tests:

  • Western blot test

Retrovirus HIV Short Question And Answers

Question 1. Mention modes of transmission of infection of HIV

Retrovirus HIV - Modes of transmission of infection of HIV

Question 2. HIV infection

  • Human immunodeficiency virus ( HIV] is the etiological agent for AIDS
  • HIV infects all cells
  • It infects primarily the CD4+ lymphocytes
  • The Center for Disease Control in Atlanta, USA, has classified the clinical course of HIV infection into various groups

Retrovirus HIV - HIV infections

Question 3. ELISA test

  • Most widely used screening test
  • It is highly sensitive and specific.
  • Direct solid phase antiglobulin ELISA is the method most commonly used for which commercial test kits are available.
  • The antigen is coated on the microtiter wells (or) another suitable solid surface.
  • The test serum is added and if antibodies are present it binds to the antigen.
  • After washing away the unbound serum, antihuman immunoglobulin linked to the suitable enzyme is added followed by color forming substrate.
  • If the test serum contains anti-HIV antibodies a visible (or) photometrical detectable color is formed which is read visually (or) by an ELISA reader.
  • ELISA has a sensitivity of over 99.5%
  • It is extremely good screening test
  • Commercial ELISA test kits contain both HIV 1 and HIV 2 antigens.

Question 4. Mention opportunistic infections associated with HIV infection

Retrovirus HIV Opportunistic infections associated with HIV infection

Question 5. Window period

  • After infection, for antibodies to appear it may take 2-8 weeks to months.
  • IgM antibodies appear first usually in about 3-4 weeks after infection and disappear in 8-10 weeks
  • IgG antibodies appear later about 5-6 weeks after infection and persist throughout
  • During part of this period, the individual may be highly infectious
  • This seronegative infective stage is known as the window period
  • Infection can be detected during the window period by p24 assay

Question 6. Rapid tests for HIV infection

  • A number of rapid tests have been introduced for the purpose of testing single samples quickly
  • They take less than 30 minutes
  • They don’t require any expensive equipment
  • These tests include:
    • Dot-blot assay
    • Particle agglutination
    • HIV spot
    • Comb tests
  • Tests using finger-pricked blood, saliva, and urine have also been developed

Question 7. Western blot test

  • Most widely used confirmatory test for HIV.
  • In this test, HIV proteins are separated according to their electrophoretic mobility and molecular weight by polyacrylamide gel electrophoresis.
  • These separated proteins are bloated on the strips of nitrocellulose paper. These strips are reacted with test sera and then with enzyme-conjugated antihuman globulin.
  • Antibodies to HIV protein present in test serum combine with all (or) any fragment of HIV.
  • These strips are washed and treated with enzyme-conjugated antihuman gammaglobulin, then a suitable substrate is added that produces colour bands.
  • The position of the band on the strip indicates the antigen with which the antibody has reacted.
  • In the positive serum, bands will be seen with multiple proteins typically with p24, p31, gp41, gpl20 (or) gpl60.

Question 8. Draw labelled diagram of HIV.

Bacteriophage Important Notes

1. Bacteriophage

  • They are viruses that infect bacteria
  • Helps in the transmission of genetic information between bacteria by transduction

Bacteriophage Short Essays

Question 1. Bacteriophage?

The viruses that infect bacteria are known as bacterio-phages

Bacteriophage Morphology:

Bacteriophages are tadpole-shaped and are made up of

1. A hexagonal head

  • The head consists of a tightly packed core of nucleic acid surrounded by a protein coat or capsid
  • The size varies from 28 nm – 100 nm.

2. A cylindrical tail and

  • The tail is composed of a hollow core, a contractile sheath surrounding the core

3. Baseplate.

  • Terminal base plate which has attached to its prongs, tail fibers or both.
  • Bacteriophages that infect E.Coli called T- even phages (T2, T4, T6) traditionally serve as the prototypes in describing the properties of bacteriophages.
  • They possess double-stranded DNA.

Bacteriophage Significance:

Bactriophage -Signification of Bactriophage

Hepatitis Viruses Virology Short And Long Essay Question And Answers

Hepatitis Viruses Important Notes

1. Hepatitis virus

Hepatitis Viruses - Hepatitis Virus

Hepatitis Viruses Long Essays

Question 1. Describe the morphology, spread, prevention, and lab diagnosis of hepatitis B virus

Hepatitis-B Virus:

It belongs to the Hepadnaviridae family

Hepatitis-B Morphology:

  • It is a complex structure
  • Size: 42 nm
  • It is a double-shelled particle

Hepatitis-B Structure:

1. Outer surface or envelope

  • It contains hepatitis B surface antigen, HBsAg.
  • It encloses the inner core

Read And Learn More: Microbiology Question and Answers

2. Core

  • It is an Icosahedral nucleocapsid
  • Size: 27 nm
  • Contains hepatitis B core antigen, HBcAg

3. Genome

  • It is present inside the core
  • It is double-stranded DNA and DNA polymerase
  • Sera of hepatitis B patients shows three types of particles microscopically.

Hepatitis Viruses - Hepatitis B Virus

Antigenic Structure:

Hepatitis Viruses Hepatitis B Virus Antigenic Structure

Hepatitis Viruses Structure of Hepatitis B Virus


There are three modes of transmission

Hepatitis Viruses - Three modes of transmission


1. General preventive measures

  • It includes:
    • Health education
    • Improvement of personal hygiene
    • Sterilization measures
    • Screening for HBsAg and HBeAg in blood donors
    • Avoiding the use of unsterile needles, syringes or other materials

2. Immunization

Hepatitis Viruses - Hepatitis B Viruses Immunization

Hepatitis-B Laboratory Diagnosis:

Hepatitis Viruses - Hepatitis B Viruses Laboratory Diagnosis

  • Dark urine and yellow coloration of sclera due to jaundice occurs
  • Blood shows lymphocytosis
  • Prolonged prothrombin time occurs

Question 2. Describe the pathogenicity and laboratory diagnosis of the hepatitis B virus.

Pathogenicity of Hepatitis B Virus:

  • Pathogenesis of hepatitis appears to be immune-mediated
  • HBV causes serum hepatitis
  • Infection spreads by
    • Blood transfusions
    • Serum inoculation
    • Sharing of syringes and needles
    • Sharing of razors
    • Tattooing
    • Acupuncture
    • Sexual intercourse
  • It is more common in drug addicts, prostitutes and homosexuals
  • Virus is highly infectious and even minute quantity of carrier sera can transmit the infection

Hepatitis B Virus Clinical Features:

  • Incubation period- 2-6 months
  • Onset – Slow, insidious, severe
  • Fever is not prominent
  • The course of acute HBV infection is divided into three phases:

Hepatitis Viruses Actue HBV infection divided

  • Extrahepatic complications include
    • Urticaria
    • Arthralgia
    • Polyarteritis nodosa
    • Glomerulonephritis
    • The appearance of circulating immune complexes obtaining viral surface antigen
  • Some patients progress to chronic active hepatitis and cirrhosis

Hepatitis Viruses Short Essays

Question 1. Differentiate between hepatitis A and hepatitis B.

Hepatitis Viruses - Differentiate between hepatitis A and hepatitis B

Hepatitis Viruses Short Question And Answers

Question 1. Danes particles.

  • Under the electron microscope, sera from type B hepatitis patients show three types of particles
  • The third type of particle is a double-walled spherical structure
  • It is 42 nm in diameter
  • It is the complete hepatitis B virus
  • It was first described by Danes in 1970
  • Hence it is known as the Danes particle

Question 2. Quantitative rapid test for hepatitis B antigen

The Serological tests used for hepatitis B antigens are

  • DNA hybridization
  • Polymerase Chain Reaction
    • They detect HBV DNA
    • They are highly sensitive
    • They are quantitative tests

RNA Viruses Virology Short Essay Question And Answers

RNA Viruses Important Notes

1. Inclusion bodies

RNA Viruses Inclusion Bodies

2. Infections caused by human papillomavirus

  • Verruca Vulgaris
  • Focal epithelial hyperplasia
  • Condyloma acuminatum

Read And Learn More: Microbiology Question and Answers

3. Types of rabies vaccine

  • Semple vaccine
  • BPL (Beta propriolactone) vaccine
  • Infant brain vaccine

RNA Viruses Short Essays

Question 1. Polio Vaccine
Immunoprophylaxis for Poliomyelitis

The two types of polio vaccines are as follows

1. Salk’s Polio Vaccine:

  • It was developed by Salk in 1953.
  • It is formalin in-activated preparation of the three types of the polio virus grown in monkey kidney tissue cultures.
  • Viral pools of adequate titre are filtered to remove the cell debris and clumps and inactivated with formalin at 37°C for 12-15 days.

Router of Administration:

The vaccine is given by deep subcutaneous (or) in- tra muscular injection.

Salk’s Polio Vaccine Doses:

Three doses are given 4-6 weeks apart followed by a booster dose should be given six months later.

  • The first dose should be given after the age of six months so that antibody response is not impaired by the residual maternal antibodies.
  • Immunity can be sustained by booster doses every 3-5 years thereafter.

Salk’s Polio Vaccine Mechanism:

  • This vaccine produces long-lasting immunity to all three poliovirus types.
  • Induces serum antibodies

2. Sabin’s Vaccine:

  • It was developed by Sabin in 1962
  • It contains live attenuated strains of poliovirus types, 1, 2, and 3 grown either in monkey kidney cells (or) human diploid cell cultures.

Sabin’s Vaccine Route of Administration:

  • It is administered orally so known as the oral polio vaccine (OPV).

Sabin’s Vaccine Mechanisms:

  • It stimulates both local secretory IgA antibodies in the intestine as well as humoral antibodies (IgM and IgG).
  • When the virus is excreted in the faeces, it may spread to close contacts
  • Thus it protects the individual and the community

Sabin’s Vaccine Doses:

  • Three doses are given
  • All doses are generally given along with DPT.
  • In addition to it, the following doses are given

RNA Viruses Sabin's vaccine Doses

Question 2. Mumps:

  • Mumps is an acute viral infectious disease character¬ised by unilateral (or) bilateral nonsuppurative enlargement of the salivary glands usually the parotid gland.
  • Submandibular and sublingual glands are occasionally involved.
  • Usually, children are affected. May also occur in adults.
  • Also known as epidemic parotitis

Mumps Causative organism:

  • Organisms involved in paramyxovirus.

Mumps Route of infection:

  • Infection is acquired by inhalation (or) direct contact or through the conjunctiva.
  • The incubation period is 12 – 18 days.

Mumps Clinical Features:

  • Unilateral (or) bilateral swelling of parotid glands.
  • Fever, malaise
  • Local pain and tender
  • The involvement of extra parotid sites can cause more serious problems as follows.
    • CNS involvement may lead to
    • Meningitis,
    • Meningoencephalitis
    • Orchitis

Mumps Complications:

  • Orchitis
  • Oophoritis
  • Arthritis
  • Nephritis
  • Pancreatitis
  • Thyroiditis and myocarditis.

Mumps Laboratory Diagnosis:

  • Isolation of viruses from CSF, saline (or) urine.
  • Serological tests with paired serum samples are tested for the rise in the titer of antibodies by complement fixation test ELISA, haemagglutination tests.
  • Serum amylase levels are elevated in both parotitis and acute pancreatitis.
  • Mumps Treatment: Treatment is conservative maintaining hydration.
  • Prevention is by means of the MMR vaccine.

RNA Viruses Short Question And Answers

Question 1. Name 3 RNA viruses and diseases caused by them.

RNA Viruses RNA virues and Diseases caused by them

Question 2. Mention two important live viral vaccines.

Live viral vaccines are

RNA Viruses Viral vaccines

Question 3. Koplik’s spots?

  • Koplik’s spots are named after Henry Koplik who first described it in 1896
  • Koplik’s spots are seen in measles (or) rubella
  • Immune reaction to the virus in endothelial cells of dermal capillaries plays a role in the development of spots.

Koplik’s Spots Appearance:

  • These are small irregularly shaped flecks
  • They appear as bluish-white flecks surrounded by a bright red margin.
  • The spots disappear after the onset of the rash.
  • Orally they are most commonly observed on the buccal mucosa opposite to the lower molars
  • With the decline of acute symptoms, widespread mac papular rash over the neck
  • It then spreads to the rest of the body
  • The rash fades in about a week
  • The patient recovers by 10-14 days

Question 4. Inclusion bodies?

  • Inclusion bodies are distinctive structures frequently formed in the nucleus (or) cytoplasm in cells infected with certain viruses.
  • These are 3 types based on location
    • Intranuclear
    • Intra cytoplasmic
    • Both.
  • They are also known as cellular inclusions.
  • Examples are:
    • Intra-cytoplasmic and intra-nuclear
      • Negri bodies – rabies
    • Intra-cytoplasmic
      • Henderson – Peterson bodies – molluscum conta- gypsum
    • Intra – nuclear
      • Cow dry type A – Herpes, yellow fever
      • Cow dry type B – Adenovirus, poliomyelitis.

Question 5. Name four vaccines

RNA Viruses Vaccines

Question 6. Mumps vaccine?

  • An effective live attenuated vaccine [Jeryl Lynn strain of mumps virus] grown in chick embryo fibroblast cul¬ture is against mumps.
  • The vaccine is given as single subcutaneous infections either alone (or) in combination with the MMR vaccine.
  • The vaccine is not protective to individuals already exposed to the virus and whose are in the incubation stage of the disease.
  • The MMR vaccine provides effective protection for a period of 10 years.

Mumps vaccine Contra-indications:

  • Pregnancy
  • Immunodeficiency
  • Hypersensitivity neomycin or egg protein.

Question 7. Arboviruses

  • Arboviruses are RNA viruses that are transmitted by blood-sucking arthropods from one vertebrate host to another
  • Mosquitoes, ticks and sandflies are the principal vectors
    • They are named according to the
      • Disease caused by them- example. Yellow fever
      • Place of isolation- for example Kyasanur forest disease
      • The local name of the disease- for example Chickengunya
    • They are classified according to their physical and chemical features into five families
      • Togaviridae
      • Flaviviridae
      • Bunyaviridae
      • Rheoviridae
      • Rhabdoviridae

Arboviruses Disease Caused by Them:

  • Encephalitis
  • Haemorrhagic fever

Arboviruses Diagnosis:

The diagnosis is made by virus isolation and serologi¬cal tests

Question 8. Rabies vaccine
Immunization of rabies

  • Rabies vaccines are two types
  1. Neural
  2. Non-neural

1. Neural Vaccines:

  • Semple vaccine:
    • The most widely used vaccine
    • Developed by Semple at Central Research Insti¬tute, Kasauli.
    • It is a 5% suspension of infected sheep brain and inactivated by 5% phenol at 37°C leaving no re¬sidual live virus.
  • Beta Propiolactone (BPL) Vacine:
    • Modified semple vaccine
    • Instead of phenol, BPL is used as inactivating agent.
  • Infant brain vaccine:
    • Used widely in South America
    • Reduce neurological complications.
  • Vaccination Schedules:
    • Nowadays not used.
    • In the past, they were given subcutaneously on the anterior abdominal wall.
    • 7 – 14 injections depend on the degree of risk.

2. Non-Neural Vaccines:

  • Duck Egg Vaccine:
    • BPL is used as an inactivating agent
    • It has poor immunogenicity so not used now.
  • Tissue culture vaccines: Following cell culture vaccines are available in India.
    • Human diploid cell strain vaccine [HDCS]
      • The HDCS vaccine is prepared by growing rabies virus on human diploid cells and is in¬activated with BPL.
      • This vaccine is highly antigenic and free of side effects
    • Purified chick embryo cell vaccine [PCEC]
      • PCEC is now widely used.
      • It is cheaper
      • It contains BPL inactivated flurry LEP strain
    • Purified Vero cell vaccine [PVC]
      • This vaccine is under study

Question 9. Kyasanur forest disease

  • It is a tick-borne haemorrhagic fever that occurs in Agar and Sorab, Shikarpur talukas of Shimoga district in Karnataka state
  • It is locally known as monkey fever as it infects mon¬keys also
  • But infection in monkeys is fatal

Kyasanur forest disease Causative Organism:

  • It is caused by the Russian Spring-Summer Encephalitis ( RSSE) Complex
  • Forest birds, and small mammals are the reservoir hosts
  • Principal vector is Haemaphysalis spinigera

Kyasanur forest disease Clinical Features:

  • Sudden onset with fever, headache, conjunctivitis, myalgia and severe prostration
  • Some may develop haemorrhages in the skin, mucosa and viscera

Question 10. Japanese Encephalitis

Japanese Encephalitis Causative Organism:

  • Japanese encephalitis virus causes Japanese B encepha¬litis.
  • The virus in one of the mosquito-borne groups of a valve viruses.
  • Culex tritaeniorhyncus – Principal vector
  • Herons – Reservoir hosts.
  • Pigs – Amplifier hosts.

Japanese Encephalitis Clinical Features:

  • The disease typically has an abrupt onset with fever, headache and vomiting.
  • The fever is high and continuous.
  • The majority of infections are asymptomatic.
  • After 1-6 days signs of encephalitis set in with nuchal rigidity, convulsions, altered sensorium and coma.
  • The majority of infections are asymptomatic.
  • After 1-6 days signs of encephalitis set in with nuchal rigidity, convulsions, altered sensorium and coma.

Japanese Encephalitis Laboratory Diagnosis:

  • There is neutrophil leucocytosis in the peripheral blood
  • Pleocytosis with normal (or) raised sugar and slightly raised protein in the CSF.

Japanese Encephalitis Immunisation:

  • A formalin-inactivated mouse brain vaccine produced by using Nakayama strain has been successfully used for human immunization in Japan and even in India also.
  • 2 doses at 2 weeks interval followed by a booster 6 – 12 months later constitutes a full course.
  • Subsequent booster doses are recommended every 3 – 4 years as the immunity produced by the vaccine is short-lived.

Question 11. Human papillomaviruses [HPV]

  • Human papilloma viruses belong to papovaviruses.
  • These are small, non-enveloped. Icosahedral oncogenic DNA viruses.
  • It can cause cutaneous warts, genital warts, recurrent respiratory papillomatosis, and oral papillomatosis.
  • These infections are transmitted by indirect (or) direct contact including sexual contact.
  • An association between HPV infection (HPV types 16 and 18) and cancer of the uterine cervix.

Question 12. Viruses causing diarrhoea.

  • Diarrhoea is defined as an increase in the frequency, fluidity or volume of bowel movements relative to the usual habits of an individual.
  • Viruses causing diarrhoea include.
    • Rotavirus
    • Norwalk virus
    • Adenovirus
    • Astrovirus
    • Coronavirus
    • Calicivirus

Question 13. Oncogenic herpes viruses

Oncogenic herpes viruses cause various malignant diseases.

RNA Viruses Oncogenic herpes viruses

Question 14. Name oncogenic viruses

The various Oncogenic viruses are as follows:

RNA Viruses Various Oncogenic viruses

Question 15. Oncogenic RNA viruses

  • Oncogenic RNA viruses belong to Retroviruses, which are enveloped, spherical viruses
  • They developed by budding through the host cell membrane
  • It contains enzyme RNA-dependent DNA polymerase or reverse transcriptase within the virion
  • It is classified into three subfamilies as follows
    • Oncovirinae
    • Spumavirinae
    • Lentivirinae
  • These viruses induce tumours by
    • Introducing into the cellular genome or by
    • Inducing or altering the expression of a pre-existing cellular gene.

Question 16. MMR.

  • It is a live viral vaccine
  • It is used for Mumps, Measles and Rubella
  • It provides effective protection for a period of 10 years
  • It is recommended for all infants at the age of 15 months followed by a booster at the age of 4-6 years.

Side effects of MMR vaccine:

  • Sore arm
  • Fever
  • Mild rash
  • Temporary pain and stiffness in joints

DNA Viruses Virology Short Essay Question And Answers

DNA Viruses Important Notes

1. Herpesvirus Subfamilies:

  • Alpha herpes virus
    • Herpes simplex 1
    • Herpes simplex 2
    • Varicella zoster
  • Beta herpes virus
    • Cytomegalovirus
  • Gamma herpes virus
    • Epstein Burr virus
    • Human herpes type 8

2. Infections caused by Epstein Barr virus

  • Infectious mononucleosis
  • Burkitt’s lymphoma
  • Nasopharyngeal carcinoma

DNA Viruses Short Essays

Question 1. Herpes virus

The Herpes virus belongs to the Herpes viridian family


DNA Viruses Subfamilies

Herpes virus Morphology:

  • Size: 100-200 nm in diameter
  • It contains:
    • Icosahedral caused containing 162 capsomers
    • Double-stranded DNA genome
      • It is surrounded by a lipid envelope containing peplomers
      • The tegument is present between capsid and envelope

Read And Learn More: Microbiology Question and Answers

DNA Viruses Morphology Of Herpesvirus

Herpes virus Laboratory Diagnosis:

  • It includes
    • Collection of specimen
    • Smear preparation
    • Staining of specimen
    • Observation
      • It shows Tzanck cells, Multinucleated giant cells, Cowdry type A intranuclear inclusion bodies
    • Tissue culture
    • Polymerase Chain Reaction

Question 2. Herpes simplex virus?

  • It is a DNA virus
  • It belongs to the herpesviridae family.
  • Man is the only natural host.
  • Herpes simplex virus are two types as follows.
    • Herpes simplex type 1 – is usually associated with oral and ocular lesions.
    • Herpes simplex type 2 – is usually associated with genital infections.
      • Lesions caused by herpes simplex depend on the site of infection, age and immune status of the individual are as follows:
    • Cutaneous infections: These include:
      • Fever
      • Blisters on the cheeks, chins around the mouth, (or) on the forehand
      • Napkin rash on the buttocks of children, – Herpetic widow in medical professionals.
    • Eczema herpeticum:
      • The generalized herpetic eruption is seen in children suffering from eczema.
    • Mucosal lesions:
      • Acute gingivostomatitis
      • Recurrent herpes labialis.
    • Ophthalmic lesions:
      • Keratoconjunctivitis
      • Follicular conjunctivitis.
    • Visceral lesions:
    • Nervous system:
      • HSV meningitis,
      • Sacral autonomic dysfunction.
    • Genital lesions:
      • Infection of the cervix, vagina, or vulva (females)
    • Congenital lesions:
      • Subclinical or localised infection of skin mouth or eyes.
      • Besides primary infections, herpes viruses may present as latent infection, reactivation and re- crude scene.

Herpes simplex virus Laboratory Diagnosis:

DNA Viruses Herpes Simplex Virus Laboratory Diagnosis

Question 3. Cytomegalovirus?

  • Cytomegalovirus is included in herpeviridae family.
  • It is a Human Herpes Virus 5 (HHV-5)
  • The virus is shed in urine, saliva, semen, cervical secretions, tears and breast milk.

Cytomegalovirus Pathogenesis:

  • Cytomegalo virus infections are almost always inapperent leading to prolonged latency with occasional re-activation.
    • Congenital infections:
      • Cytomegalovirus can be transmitted transplacentally from a mother with latent infection to the foetus.
      • Infections are asymptomatic at birth (or) it may lead to cytomegalic inclusion disease which is often fatal.
      • Cytomegal inclusion disease is characterised by:
        • Hepatosplenomegaly.
        • Jaundice
        • Thrombocytopenic purpura
        • Haemolytic anaemia
        • Microcephaly.
    • Post Natal Infections:
      • Are usually asymptomatic
      • Clinical disease in adults resembles infectious mononucleosis.
      • It can cause dissemeinated infection in immune-compromised individuals like AIDS patients.

Cytomegalovirus Laboratory diagnosis:

  • Specimens can be obtained from saliva, urine, breast milk, semen etc.
  • The smear shows enlarged cytomegalic cells with large intra-nuclear owl’s eye appearance
  • Inclusions can be demonstrated in the centrifuged de-posits from urine (or) saliva.
  • The virus can be grown in human fibroblast culture detected by ELISA test.

Cytomegalovirus Treatment:

Ganciclovir is the drug of choice.

Question 4. Adenovirus

  • Adenovirus belongs to the Adenoviridae family
  • They replicate in the nucleus of infected cell

Adenovirus Classification:

  • Adenovirus are grouped into
    • Aviadenovirus- Possess avian adenovirus
    • Mastadenovirus- Possess mammalian adenovirus

Adenovirus Morphology:

  • Size- 70-75 nm in diameter
  • It is non-enveloped
  • Contains
    • Icosahedral capsid
    • Double-stranded DNA

Adenovirus Pathogenesis:

  • Adenovirus causes infections of the respiratory tract, eye, GIT and urinary tract
  • The mode of the spread of infections include
    • Conjunctiva
    • Nasal mucosa
    • Faeco-oral spread
  • The incubation period is 5-7 days

Adenovirus Laboratory Diagnosis:

DNA Viruses Adenovirus Laboratory Diagnosis

DNA Viruses Short Question And Answers

Question 1. Smallpox

  • The causative organism of smallpox is the variola virus
  • It was exclusively human infection with no animal reservoir
  • It used to occur in two distinct varieties

1. Florid

  • It is a highly fatal disease
  • Seen in Asia

2. Alastrim

  • It is a mild non-fatal disease
  • Seen in Latin America
  • Variola major caused smallpox
  • Now it has been eradicated
  • Due to which the vaccination of it is now stopped
  • It was last detected in Somalia, in October 1977.
  • On May 8, 1980, WHO announced the global eradication of small pox

Question 2. Name the disease caused by DNA viruses.

DNA Viruses Disease Caused by DNA Viruses

Question 3. Herpes Zoster

  • It is caused by the Varicella Zoster virus
  • It is a disease of old age
  • It occurs in persons who had chickenpox several years earlier

Herpes Zoster Pathogenesis:

  • The virus remains latent in the sensory ganglia
  • Due to a decrease in immunity, this virus gets reactivated
  • It is triggered by some precipitating stimulus
  • It results in the inflammation of the nerve

Herpes Zoster Clinical Features:

  • Skin lesions
  • Neuritic pain- It is severe and persists for weeks or months
  • Unilateral Vesicles
  • Oral manifestations include:
    • Unilateral involvement of skin areas supplied by ophthalmic, mandibular or Maxillary nerves
    • Painful vesicles are present on the buccal mucosa, tongue, pharynx and larynx
    • Vesicles rupture leaving areas of erosion

Question 4. Antiviral agents

Antiviral agents are agents that selectively attack one of the stages of viral replication without harming the host cells.


DNA Viruses Antiviral agents examples

Question 5. Epstein- Barr virus or EB virus

  • Epstein-Barr virus is named after its discoverers Epstein, Barr and Achong in 1964.
  • Infection with the EB virus leads to
    • Latency
    • Periodic reactivation
    • Lifelong persistence
    • Infects B lymphocytes
  • Diseases caused by it are
    • Infectious mononucleosis
    • EBV associated malignancies
      • Burkin’s lymphoma
      • Lymphoma in immuno-deficient persons
      • Nasopharyngeal carcinoma

General Properties Of Viruses Virology Short And Long Essay Question And Answers

General Properties Of Viruses Important Notes

1. Features of virus

  • Lacks enzymes required for protein and nucleic acid synthesis
  • Do not possess cellular organization
  • Contains only one type of nucleic acid
  • Multiply by a complex process

2. Structure Consists of

  • Genome
  • Capsid
  • Envelope

3. Cultivation of virus

  • Animal inoculation
  • Embryonated egg inoculation
  • Tissue culture

4. Classification of virus

  • Enveloped and non-enveloped virus
  • Based on their affinity to a different system
    • Thermotropic
    • Neurotropic
    • Pneumotropic
    • Viscerotropic

General Properties Of Viruses Long Essays

Question 1. Explain the methods of isolation of viruses.

Methods employed for the cultivation of viruses are

  • Animal inoculation.
  • Embryonated egg inoculation.
  • Tissue culture.
    • Organ culture
    • Explant culture
    • Cell culture

Read And Learn More: Microbiology Question and Answers

  • Animal inoculation Uses:
    • Primary isolation of certain viruses
    • To study viral oncogenesis
    • To study the pathogenesis of certain viruses.
    • Animals used are
      • Mice – for arboviruses and coxsackie virus
      • Guinea pigs.
      • Rabbits
    • Routes of inoculation used
      • Intracerebral
      • Sub-cutaneous
      • Intraperitoneal
      • Intranasal
    • Steps
      • Inoculation of animals
      • Observation of animals for signs of disease
      • Animals are killed
      • Their tissues are tested for the presence of virus
  • Embryonated egg inoculation:
    • Embryonated hen’s eggs are inoculated by different routes

General Properties Of Viruses Embryonated hen's eggs are inoculated by different routes

  • Tissue Cultures:
    • Cell Culture:
      • Routinely employed for diagnostic virology.
      • Tissues are disassociated into the component cells by the action of proteolytic enzymes such as trypsin.
      • Cell cultures are classified into three types based on their origin, and chromosomal characteristics.

General Properties Of Viruses Classification of cell cultures

General Properties Of Viruses Short Essays

Question 1. Mention the characters of viruses.

General Characters of Viruses:

  • Viruses are the smallest obligate intracellular infective agents.
  • Only one type of nucleic acid either DNA (or) RNA act as their genomes.
  • They have no metabolic activity outside the living cells.
  • They do not possess a cellular organization.
  • They lack the enzymes necessary for protein and nucleic acid synthesis.
  • They do not grow in inanimate media.
  • They are resistant to antibiotics.
  • They multiplied by a complex process but not by binary fusion.
  • They are ultramicroscopic particles.

General Properties Of Viruses Short Question And Answers

Question 1. Classification of viruses

  • Viruses are classified into two major groups based on the nucleic acid they possess
  • They are:

Dna Viruses:

  • Poxviridae family
  • Herpes viridian family
  • Adeno viridian family
  • Pap ova viridian family
  • Parvo viridian family
  • Hepadna viridae family

Rna Viruses:

  • Picorna viridae family
  • Orthomyxo viridian family
  • Paramyxo viridian family
  • Toga viridian family
  • Flavi viridian family
  • Rhabdo viridian family
  • Retro viridian family
  • Corona viridae family
  • Filoviridae family