EBVS European College diplomas Clinical, Diagnostic & Immuno-Parasitology: practice questions

Question 1 · medium

A flotation device reads two chambers of 1 mL each from a suspension of 5 g of faeces made up to 50 mL. What is its analytical sensitivity (EPG represented by one egg)?

1. 5 EPG
2. 50 EPG
3. 10 EPG
4. 4.5 EPG

Question 2 · hard

A practice offers flock monitoring by composite faecal egg count (equal weights from ten lambs pooled). Which statement about composite counts is correct?

1. They give each lamb's count once the pooled result is divided by ten
2. They are invalid for any resistance testing because the pooling step destroys strongyle eggs
3. They estimate the group mean well but cannot show which individuals are high shedders
4. They are less accurate than one individual count because pooling dilutes the eggs

Question 3 · hard

A coprophagic dog's flotation shows large numbers of Eimeria oocysts and some strongyle-type eggs. The dog is healthy. The most likely explanation is:

1. Pseudoparasites such as pollen grains and mites
2. Spurious parasitism
3. Canine coccidiosis caused by Eimeria species
4. Ancylostoma infection with coccidial co-infection

Question 4 · hard

A flock has itchy sheep but surface scrapings are negative. Which additional test can detect Psoroptes ovis infestation at flock level, even early in infestation?

1. A McMaster count of faecal mite eggs from ten ewes
2. A modified Knott's test on pooled jugular blood
3. An ELISA for serum antibodies against Psoroptes ovis
4. A Giemsa smear of wool fibres from the shoulder area

Question 5 · hard

A test has sensitivity 90% and specificity 95%. It is used where 10% of animals are infected. What is the positive predictive value?

1. 99%
2. 95%
3. 67%
4. 90%

Question 6 · hard

A serosurvey finds 25% of animals positive with a test of sensitivity 80% and specificity 95%. Using the Rogan–Gladen estimator, the true prevalence is about:

1. 31.3%
2. 25.0%
3. 20.0%
4. 26.7%

Question 7 · hard

Two independent tests with sensitivities 80% and 70% are used in parallel (an animal is positive if either test is positive). The combined sensitivity is:

1. 56%
2. 150%
3. 94%
4. 75%

Question 8 · hard

Which factor is NOT a recognised reason why vaccines against parasites have been slow to develop?

1. Parasites have too few antigens for the immune system to recognise
2. Cheap, broad-spectrum antiparasitic drugs set a high commercial bar
3. Parasites have multiple life stages expressing different antigens
4. Many parasites actively evade or modulate host immune responses

Question 9 · hard

Ten treated lambs have post-treatment counts (EPG) of 0, 0, 50, 0, 100, 0, 0, 50, 0, 0; the untreated control mean is 400 EPG. Using arithmetic means, what is the FECR?

1. 95%
2. 83%
3. 50%
4. 5%

Question 10 · hard

Demodex mites are found in deep scrapings from an adult dog that has developed generalised demodicosis for the first time at 8 years of age. What is the most important next step besides treating the mites?

1. Treat all in-contact dogs, as adult-onset demodicosis is contagious
2. Look for underlying disease or immunosuppressive treatment
3. Stop investigating, as Demodex is never found in normal dogs
4. Test the owners, as Demodex canis is a major zoonosis