National Veterinary Examination Veterinary Epidemiology & Zoonoses: practice questions

1 · Terms of disease occurrence: sporadic, enzootic, epizootic, panzootic and exotic · easy

A disease that is present in a cattle population at a usual, fairly constant and predictable frequency is described as:

1. Enzootic
2. Epizootic
3. Sporadic
4. Exotic

2 · Measures of disease frequency: incidence, prevalence, morbidity, mortality and case fatality · easy

In a cross-sectional survey, 48 of 600 goats tested are positive for an infection on the day of sampling. What is the prevalence?

1. 8.0%
2. 8.7%
3. 12.5%
4. 0.8%

3 · Measures of disease frequency: incidence, prevalence, morbidity, mortality and case fatality · easy

During an outbreak of respiratory disease, 40 calves become ill and 6 of them die. What is the case fatality rate?

1. 6%
2. 17.6%
3. 40%
4. 15%

4 · Epidemiological study designs · medium

A case-control study of salmonellosis in herds gives: cases exposed 40, cases unexposed 60, controls exposed 20, controls unexposed 80. What is the odds ratio?

1. 2.67
2. 1.56
3. 2.00
4. 0.38

5 · Surveillance · easy

A national system relies on farmers and private veterinarians to report suspect cases of disease to the veterinary authority. This is:

1. Passive surveillance
2. Targeted active surveillance
3. Sentinel surveillance
4. Participatory surveillance

6 · Outbreak investigation · medium

In a feed-associated outbreak, 80 broilers received a particular batch of feed and 20 became ill. What is the attack rate among birds that received it?

1. 20%
2. 4%
3. 25%
4. 80%

7 · Zoonoses: rabies, brucellosis, tuberculosis and anthrax · easy

A cow is found dead with dark unclotted blood oozing from the nostrils and anus and no rigor mortis. What should be done first?

1. Perform a full necropsy at once to examine the spleen for enlargement and to collect tissue samples from every organ
2. Skin the carcass carefully to salvage the hide, then bury the remains at least two metres deep on the same farm
3. Do not open the carcass; take a peripheral blood smear for polychrome methylene blue stain and inform the authorities
4. Send the carcass for rendering without delay so that no other animals can feed on it

8 · Zoonoses: leptospirosis, glanders, KFD, avian influenza and Japanese encephalitis · medium

Why are H5 and H7 low pathogenicity avian influenza viruses in poultry a regulatory concern?

1. They are always highly pathogenic for humans and spread readily from person to person after any exposure to poultry
2. HPAI viruses have so far arisen only from H5 and H7 subtypes, which can mutate to high pathogenicity in poultry
3. They cannot be detected by any laboratory test, so infected flocks go unnoticed until they die
4. They infect only mammals

9 · Measures of disease frequency: incidence, prevalence, morbidity, mortality and case fatality · easy

Point prevalence measured in a single cross-sectional survey is most useful for:

1. Estimating the risk that a healthy animal will become diseased during the next month
2. Estimating the current burden of disease to plan treatment or control work
3. Measuring the speed at which new cases occur
4. Measuring how often diseased animals die

10 · Surveillance · easy

Planned testing of a random sample of herds by the veterinary authority to measure brucellosis prevalence is an example of:

1. Passive surveillance
2. Syndromic surveillance
3. Active surveillance
4. Participatory surveillance