Table 7 Available liver fluke diagnostic techniques, when to use them and their characteristics (valid for western Europe)

Blood antibody ELISA

From approx. 3–4 weeks post-infection

Regular blood sampling. Use first-season grazing animals (lambs and/or calves) as “sentinels” and 10 animals per risk group (consider on-farm risks, such as grazing)

Measure of acute disease risk. Increasing antibody levels identify when active infection is occurring for targeted treatment

Careful interpretation of test results is required to avoid premature treatment. Test results for sentinel animals indicate risk status only for their group. Antibody levels can remain high even after successful treatment and in previously exposed older animals

Coproantigen ELISA

From approx. 8–10 weeks post-infection

Dung, individual (avoid using pooled if possible)

Mid- to late-stage infection

Low sensitivity in cattle and in pooled samples. If result is negative, advise re-test in approx. 4 weeks

Milk ELISA

From approx. 2–4 weeks post-infection

Bulk milk tank

Monitoring the parasite-infection status of a herd

Test results are associated with parasite-induced production losses

Antibodies can persist until 8 months after effective treatment

Fluke egg counts

From approx. 10–11 weeks post-infection

Dung, individual and pooled

Definitive diagnosis when adult parasites present

Test sensitivity may be low, especially in cattle. If result is negative, advise re-test in 4–8 weeks

Post-mortem

From approx. 2 weeks post-infection

Fallen stock

Definitive diagnosis (all stages of infection)

Abattoir returns are useful, but should not be considered equivalent to veterinary post-mortem in terms of reliability