Infection Definitions Question And Answers

Infection Definitions

Definition of Health: Health is a state of complete physical, mental & social well-being & not merely the absence of disease or infirmity

Agent Definition: It is defined as “an organism, a substance or a force, the presence or lack of which may initiate a disease process or may cause it to continue”

Host Definition: It is defined as “a person or an animal that affords subsistence or lodgement to an infectious agent under natural conditions

Sensitivity Definition: Defined as the ability of a test to identify correctly all those who have the disease i.e. true positive

Specificity Definition: Defined as the ability of a test to identify correctly those who do not have the disease i.e. true negative

Morbidity Definition: WHO has defined it as “any departure, subjective or objective, from a state of physiological well-being”

Mortality Definition: It is the condition of being mortal, or susceptible to death

Incubation Period Definition: It is the time interval between invasion by an infectious agent & appearance of the first sign or symptom of the disease in question

Risk Factor Definition: It is an attribute/ exposure that is significantly associated with the development of disease.

Latent Period Definition: It is a period between the disease initiation to the disease detection.

Disease Definition: Webster defined disease as “a condition in which the body’s health is impaired, a departure from a state of health, an alteration of the human body interrupting the performance of vital functions”.

Spectrum Of Disease Definition: It may be defined as the sequence of events that occur in the human host from the time of contact with the etio- logical agent upto the point of the ultimate outcome, which may be fatal in extreme cases

Carrier Definition: A carrier is defined as an infected person or animal that harbors a specific infectious agent in the absence of dis- credible clinical disease and serves as a potential source of infection for others.

Screening Definition: It is defined as the use of presumptive methods to identify unrecognized health risk factors or asymptomatic diseases in persons determined by prior studies to be potentially at elevated risk & able to benefit from interventions performed before overt symptoms develop.

Infection Important Notes

1. Screening for lung cancer includes two techniques: chest radiograph and sputum cytology
2. The main causes of maternal mortality rate are hemorrhage, sepsis, abortion, obstructed labor, and hypertensive disorders.
3. Modes of transmission of disease
   1. Direct Transmission
      • Direct contact
      • Droplet infection
      • Contact with soil
      • Inoculation into skin and mucosa
      • Transplacental
   2. Indirect Transmission
      • Vehicle borne
      • Vector-borne
      • Airborne
      • Fomite borne
      • Unclean hands and fingers

4. Various measures used to evaluate screening test

1. Sensitivity
2. Specificity
3. Positive predictive value
4. Negative predictive value

5. Positive predictive value indicates the probability of a patient with a positive result has the disease. Negative predictive- it is a test to correctly exclude the disease

6. Types of carriers:

1. Incubatory Carrier
   • These carriers shed infectious agents during the incubation period of the disease.
   • Examples: Measles, mumps, polio, pertussis
2. Convalescent Carriers
   • Shed the disease agent during the period of recovery from illness.
   • Examples: Typhoid, cholera, diphtheria
3. Healthy Carriers
   • Emerge from subclinical cases.
   • Examples: polio, cholera, diphtheria
4. Temporary Carriers
   • Shed the infectious agent for short periods of time.
   • Examples: incubatory, convalescent, and healthy carriers.
5. Chronic Carriers
   • Excretes the infectious agent for indefinite periods.
   • Examples: typhoid, hepatitis B, malaria, and gonorrhea.

Infection Long Essays

Question 1. Define Health. Enumerate the various environmental factors necessary for the maintenance of the general health of the individual.
Answer:

Health Definition: Health is a state of complete physical, mental & social well-being & not merely the absence of disease or infirmity

• The environment is the source of the agents of disease
  • It helps in the transmission of agents to the host
  • It may be favorable to the man & unfavorable to the agent or vice versa

Types Of Environments:

1. Internal Environment:

• It pertains to each & every component part, every tissue, organ & organ system & their harmonious functioning within the system
• Defect or deficiency in the functioning of one or more component parts results in disease of the individual

2. External Environment:

• It comprises all that is external to the individual human host
• It comprises of individual’s lifestyle
• When the individual is well-adjusted, he is in a state of health
• The imbalance of the body is responsible for disease

Components:

Physical Component: It comprises nonliving things & physical factors of man’s surroundings

3. Biological environment: It includes living things surrounding man including the man himself

4. Social environment:

• It comprises all human beings around man, their ac- activities & interactions
• It includes
  1. Social factors
     • It pertains to the society in which man lives
     • It affects the physical, mental & social state of man which he must adjust
  2. Economic factors
     • It determines the economic status of man
     • Low economic status means less diet, poor housing & fewer resources for medical aid

Infection Short Essays

Question 1. Epidemiological triad
Answer:

Epidemiological triad

1. The occurrence of any disease is determined by the interaction between the agent, host & environment con- stituting epidemiological triad

Agent:

• It is defined as “an organism, a substance or a force, the presence or lack of which may initiate a disease process or may cause it to continue”

1. It is classified as

• Biological agents: Example: bacteria, viruses, fungi
• Non-living agents
• Nutrient agents: Example: protein, fat, water

1. Chemical agents
   • External: lead, arsenic
   • Internal: urea, ketone
2. Physical agents: heat, cold, pressure
   • Mechanical agents: chronic friction
   • Social agents: smoking, poverty, isolation

Host:

• It is defined as “a person or an animal that affords subsistence or lodgement to an infectious agent under natural conditions

1. Host factors are classified as:

• Demographic characteristics: age, sex
• Biological characteristics: genetics, immunity
• Socio-economic characteristics: Education
• Lifestyles characteristics: living habits, food habits

Environment:

• It is a reservoir for the agent of diseases

Components: refer to the previous question

Question 2. Changing concepts of health.
Answer:

Changing concepts of health

1. Biomedical concept:

• According to it, health is viewed as an “absence of disease
• It is based on the Germ theory of disease
• This concept was found inadequate as it does not take into consideration environmental social & cul-subjective or cultural determinants of health

2. Ecological concept:

• According to it, health is viewed as a dynamic equilibrium between man & his environment & disease is a maladjustment of the human organism to the environment
• It focuses on imperfect man & imperfect environment

3. Psychosocial concept:

• According to it, health is influenced by social, psychological, cultural, economic & political factors

4. Holistic concept:

• It implies that all sectors of society have an effect on health
• Health implies a sound mind, a sound body, and a sound family, in a sound environment

Question 3. Sensitivity & specificity.
Answer:

Sensitivity:

• Introduced by Yerushalmy in the 1940s
• Defined as the ability of a test to identify correctly all those who have the disease i.e. true positive

Specificity:

• Defined as the ability of a test to identify correctly those who do not have the disease i.e. true negative

Inter-Relation

• Sensitivity may be increased only at the cost of specificity & vice versa

Significance:

• An ideal screening test should be 100% sensitive & 100% specific

Evaluation:

• Sensitivity(true positive) = a/(a+c)*100
• Specificity (true negative) = d/(b+d)*100
  • a = that individual found positive on the test who has the condition/disorder
  • b= those who have a positive test result but do not have the disease
  • c=hose with negative results but who have the disease
  • d = those with negative results but do not have the disease

Question 4. Morbidity & mortality. disease”
Answer:

Morbidity:

• WHO has defined it as “any departure, subjective or objective, from a state of physiological well-being”

1. It is based on

• Persons who are ill
• The illnesses/diseases these people experienced
• The duration of these illnesses/disease

2. Uses:

• Describe the extent & nature of the disease
• Provide more comprehensive, accurate & clinically relevant information on patient characteristics
• Serve as a starting point for etiological studies
• Monitor & evaluate disease control activities

3. Morbidity Rates:

• Incidence & prevalence
• Notification rates
• Attendance rates at the out-patient department
• Admission, readmission & discharge rates
• Duration of stay in hospital
• Spells of sickness/absence from work

Mortality:

• It is the condition of being mortal, or susceptible to death

1. Measures of Mortality:

• Crude death rate
  1. It is defined as “the number of deaths per 1000 people in a population in a given year”
     • Age-specific death rate
  2. It is the death rate specific to a given age group
     • Case fatality rate
  3. It represents the killing power of disease
     • Proportional mortality rate
  4. It is defined as “the number of deaths due to a particular cause per 100 or 1000 total deaths”

 

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Question5. Greek medicine.
Answer:

Greek medicine

• In Greek medicine, Hippocrates is called the “Father of medicine”
• He studied & classified diseases based on observation & reasoning
• The Hippocratic concept of health & disease stressed the relationship between man & the environment
• Greeks gave a new direction to medical thought
• They rejected the supernatural theory of disease & looked upon disease as a natural process, not a visitation from the God
• Hippocrates initiated the application of clinical methods in medicine

Question 6. Screening for oral diseases.
Answer:

Screening for oral diseases Definition:

• It is defined as the use of presumptive methods to identify unrecognized health risk factors or asymptomatic disease in persons determined by prior studies to be potentially at elevated risk & able to benefit from interventions performed before overt symptoms develop

Screening for oral diseases Criteria:

1. Acceptability:

• The screening test should be acceptable to the people at whom it is aimed
• Tests that are painful, discomforting, and embarrass- ing is not likely to be acceptable

2. Repeatability:

• The test must give consistent results when repeated more than once on the same individual/ material, under the same condition
• It depends upon observer variation, biological variation & errors relating to technical methods

3. Validity:

• It expresses the ability of the test to separate or dis- tinguish those who have disease from those who do not

Screening for oral diseases Uses:

• Case detection
• Control of diseases
• Research purposes
• It provides opportunities for public awareness

Question 7. Indicators of health.
Answer:

Indicators of health Uses:

• Measures the health status of a community
• Compare the health status of one country with that of another
• Assess the health care needs
• Allocate the scarce resources
• Monitor & evaluate health services
• Help to measure the extent of achievement of objectives of the programs

Indicators of health Characteristics:

• The ideal indicator should be
• Valid
• Reliable
• Sensitive
• Specific
• Feasible
• Relevant

Classification of Indicators of health:

• Mortality indicator
  • Crude death rate
  • Expectations of life
• Morbidity indicator
• Disability rates
  • Event-type indicator
  • Person-type indicator
• Nutritional status indicator
  • Anthropometric Measurement of preschool children
  • Heights of children at school entry
  • Prevalence of low birth weight
• Healthcare delivery indicator
  • Doctor-population ratio
  • Doctor-nurse ratio
  • Population-bed ratio
  • Population per health/subcentre
  • Population per traditional birth attendant
• Utilization rates
  • It is the proportion of people in need of a service who ac- actually receive it in a given period usually a year
• Indicators of social & mental health
• Environmental indicator
• Socio-economic indicator
  • Rate of population increase
  • Level of unemployment
  • Family size
• Health policy indicator
• Indicators of quality of life
  • Infant mortality
  • Life expectancy at age one
  • Literacy
• Other indicators
  • Social indicator
  • Basic needs indicator
  • Health for all indicator

Infection Short Question And Answers

Question 1. Determinants of health.
Answer:

The determinants of health include

1. Social and economic status:

• Higher income and social status are linked to better health
• The greater the gap between the richest and poor- est, the greater the differences in health

2. Education: Low education levels are linked with poor health, more stress, and lower self-confidence

3. Physical environment: Safe water and clean air, healthy workplaces, safe houses, and community and roads all contribute to good health

4. Personal behavior and coping skills: Balanced eating, keeping active, smoking, drinking, and how we deal with life’s stresses and challenges all affect health

Question 2. Risk factor.
Answer:

Risk factor

1. It means:

• An attribute/exposure that is significantly associated with the development of a disease
• The presence of a risk factor does not imply that the disease will occur & in its absence, the disease will not occur
• A combination of risk factors in the same individual may be purely additive/synergetic
• Risk factors may be truly causative or merely con- tributary or they may be predictive only in a statistical sense
• Some risk factors ex. Smoking can be modified while others like age, and sex cannot be modified

2. Significance:

• It will help in the prevention & intervention of disease
• It may characterize the individual, the family, the community & the environment

Question 3. A holistic view of health.
Answer:

A holistic view of health

• It implies that all sectors of society have an effect on health
• Health implies a sound mind, a sound body, and a sound family, in a sound environment

Question 4. Iceberg phenomenon.
Answer:

Iceberg phenomenon

According to the iceberg phenomenon, disease in a community may be compared to an iceberg

Tip Of Iceberg: Represents what the physician sees in the community i.e. clinical cases

1. Vast Submerged Portion:

• Represent latent, inapparent, presymptomatic & undiagnosed cases
• It is an important part as many inapparent infections can be transmitted & can produce disease in others

2. Water Line: It represents the demarcation between apparent & inapparent disease

Question 5. Sullivan index.
Answer:

Sullivan index

1. It is calculated by subtracting from the life expectancy the probable duration of bed disability & inability to perform major activities
2. It is based on cross-sectional data

Question 6. Incubation period.
Answer:

Incubation period

1. It is the time interval between invasion by an infectious agent & appearance of the first sign or symptom of the disease in question
2. An infection becomes apparent only after a certain incubation period
3. During the incubation period, the infectious agent undergoes multiplication in the host
4. When a sufficient density of the disease agent is built up in the host, the health equilibrium is disturbed & the disease becomes overt
5. It is the first stage of infectious disease
6. The incubation period of non-infectious disease may be months/years.

Question 7. True positive.
Answer:

True positive

1. It denotes those individuals found positive on the test, who have the condition/disease/ disorder being studied
2. It is denoted as ‘a in screening for diseases.

Question 8. Latent period.
Answer:

Latent period

1. It is defined as “the period from disease initiation to disease detection”
2. It is used in case of non-infectious disease as Incuba- the time period is used in case of infectious disease

Question 9. The germ theory of disease.
Answer:

The germ theory of disease

1. It proposes that the micro-organism are the cause of many diseases
2. Dr. John Snow contributed to the formation of it
3. It is generally referred to as the one-to-one relationship between causal agent & disease
   • Disease agent man→ disease
4. The emphasis had shifted from empirical causes to microbes as the sole cause of the disease

Question 10. A spectrum of disease.
Answer:

A spectrum of disease

1. It may be defined as the sequence of events that occur in the human host from the time of contact with the etiological agent upto the point of the ultimate out- come, which may be fatal in extreme cases
2. At one end of the disease spectrum are subclinical infections & at the other end are fatal illnesses
3. In the middle of the spectrum lie illnesses ranging in severity from mild to severe
4. The sequence of events in the spectrum of disease can be interrupted by early diagnosis & treatment or by preventive measures

Question 11. Define Health.
Answer:

Health

• Health is a state of complete physical, mental & social well-being & not merely the absence of disease or infirmity

Question 12. Define Disease.
Answer:

Disease

Webster defined disease as “a condition in which the body’s health is impaired, a departure from a state of health, an alteration of the human body interrupting the performance of vital functions”.

Question 13. World Health Day.
Answer:

World Health Day

• The Constitution of WHO came into force on 7th April 1948
• So it is celebrated as World health day
• Every year a theme is selected and global attention is focused on that particular theme
• World Health Day theme of 1994 focused on oral health as ” Oral health for a healthy Life”.

Infection Viva Voce

1. World health day is on 7th April.
2. Zoonotic describes a disease transmitted to man through animals.
3. The airborne source of infection is the most difficult to control.