High proportion of horses in Germany positive for antibodies against Anoplocephalidae

Tapeworms are often overlooked intestinal parasites in horses, although infections can potentially cause clinical disease. Antibody-detection-based diagnostic methods have significant advantages for estimating the proportion of horses positive for tapeworms, as some faecal routine examinations are often limited by low sensitivity.

Data were obtained in the federal states Brandenburg, Bavaria, Lower Saxony, North Rhine-Westphalia, Saxony and Schleswig-Holstein. Coproscopy was performed using the Mini-FLOTAC technique (n = 970). Antibodies against the Anoplocephala perfoliata excretory-secretory 12-13 kDa antigen complex were measured using saliva- (n = 969) and plasma- (n = 957) based ELISAs (n = 923 paired samples). These data were combined with responses to a questionnaire to assess risk factors associated with tapeworm infection.

Tapeworm eggs were found in 0.7% (n = 7) faecal samples. Saliva-based ELISA testing identified positive tapeworm results in 20.1% of horses, with 60.4% of yards having at least one positive horse, while in the plasma-based ELISA, 11.0% of horses and 47.4% of yards were positive. Risk factor analysis using multivariable generalised estimating equations for binomial data, based on saliva ELISA results, showed that geographical origin was a significant determinant of infection risk. Horses from Brandenburg had the highest odds of testing positive (odds ratio [OR] 18.7; proportion 42.1%), while horses from Lower Saxony, Saxony and North Rhine-Westphalia also showed significantly higher odds (OR 4.1-12.4; proportion 17.4-32.2%) compared with Schleswig-Holstein (4.0%). Bavaria was the only state that did not differ significantly from Schleswig-Holstein (OR 2.7; proportion 9.0%). Another important factor was age: horses under 1 year (OR 0.41) or older than 5 years (OR 0.43) had significantly lower odds (P < 0.001) compared to horses aged 1-5 years. Strongyle faecal egg counts increased the odds of individuals being Anoplocephala-positive, with odds increasing 1.07-fold with every increase in egg counts by 100 (P < 0.001).

The ELISA results show that horses in Germany are more frequently positive for Anoplocephalidae than indicated by Mini-FLOTAC. Strong regional differences in tapeworm saliva test positivity and the relatively low number of horses treated against tapeworms emphasise the importance of applying tapeworm diagnostics in control programmes.