Australasian Veterinary Examination, formerly the National Veterinary Examination Veterinary Epidemiology & Zoonoses: practice questions

1 · 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%

2 · 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

3 · Evaluation of diagnostic tests: sensitivity and specificity · medium

A test applied to 1,000 animals gives TP 90, FN 10, FP 45 and TN 855. What is the negative predictive value?

1. 98.8%
2. 95%
3. 90%
4. 66.7%

4 · 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%

5 · Zoonoses: rabies, brucellosis, tuberculosis and anthrax · medium

A healthy, vaccinated pet dog bites a person. Under the approach used in many countries, what is the standard animal-side step?

1. Euthanase the dog immediately and test the brain in every case, whatever its vaccination status
2. Observe the dog for 10 days; if it stays healthy it was not shedding rabies virus when it bit
3. Vaccinate the dog again and take no further action
4. Take a blood sample for rabies antibody and use the titre to decide on the person's treatment

6 · Zoonoses: rabies, brucellosis, tuberculosis and anthrax · medium

In a brucellosis programme, the Rose Bengal test is followed by the complement fixation test only in Rose Bengal-positive animals. What is the effect of this series interpretation?

1. Sensitivity increases and specificity decreases compared with either test used alone
2. Both sensitivity and specificity increase
3. Neither changes, because the two tests are independent and measure different antibodies
4. Specificity increases and sensitivity decreases compared with either test alone

7 · Zoonoses: leptospirosis, glanders, KFD, avian influenza and Japanese encephalitis · hard

After severe floods, several rice farmers are admitted with fever, jaundice and kidney failure. Which zoonosis is the most likely cause?

1. Brucellosis
2. Kyasanur Forest disease
3. Glanders
4. Leptospirosis

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