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
Answer:

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

Read And Learn More: Microbiology Question and Answers

Ankylostomiasis Pathogenicity:

• Migrating larvae may cause three types of lesions as follows

• 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:

2. Indirect methods:

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

Tapeworms:

• Taenia saginata
• Taeniasolium
• Echinococcus granulosus

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

Taenia Solium Laboratory Diagnosis

1. Stool examination

• It detects eggs of T. solium

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

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

Wuchereria Branchfti Morphology:

1. Adult worms

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

• 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

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

Wuchereria Branchfti Pathogenesis:

• W. bancrofti causes filariasis

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:
Answer:

• 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
Answer:

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
Answer:

• 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:

Question 5. Cysticercus Ceilulosae
Answer:

• 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
Answer:

Question 7. Life cycle of Ascaris lumbricoides
Answer:

• 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

Question 8. Larva migrans
Answer:

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.
Answer:

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