Seroprevalence and GIS-supported risk factor analysis of Fasciola hepatica infections in dairy herds in Germany.

A total of 20 749 bulk tank milk (BTM) samples was collected in November 2008 from all over Germany, corresponding to 20.9% of all German dairy herds. The BTM samples were analysed for antibodies against Fasciola hepatica using the excretory-secretory (ES) ELISA. A geospatial map was drawn to show herd prevalences per postal code area. Various spatial risk factors were tested for potential statistical associations with the ELISA results in logistic regression supported by a geographical information system (GIS). The mean seroprevalence was 23.6% and prevalences in different German federal states varied between 2.6% and 38.4%. GIS analysis revealed statistically significant positive associations between the proportion of grassed area and water bodies per postal code area and positive BTM ELISA results. This can be explained by the biology of the intermediate host, the amphibious snail Galba (Lymnea) truncatula and the pasture-borne nature of fasciolosis. The full logistic regression model had a Pseudo-R 2 of 22%, while the final model obtained by controlled stepwise model building revealed a Pseudo-R 2 of 14%, indicating that additional, unrecorded factors and random effects contributed substantially to the occurrence of positive ELISA results. Considering the high seroprevalences in some areas and the economic impact of fasciolosis, farmers and veterinarians should be strongly advised to implement effective liver fluke control programmes.

Evaluation of a recombinant cathepsin L1 ELISA and comparison with the Pourquier and ES ELISA for the detection of antibodies against Fasciola hepatica.

The liver fluke Fasciola hepatica is one of the most important parasites in cattle farming worldwide and responsible for serious economic losses. In this study, three ELISAs for the detection of antibodies against F. hepatica were compared by analysis of serum antibody levels of 20 calves infected with different doses (50-1000 metacercariae) of F. hepatica metacercariae. The commercially available Pourquier ELISA was tested against an in-house ELISA based on excretory-secretory (ES) products as well as an ELISA based on recombinant cathepsin L1 (rCL1). During the period 4-21 weeks post infection (pi) the Pourquier ELISA showed 100% sensitivity (Se) and 100% specificity (Sp). ROC-analyses revealed a cut-off value of 0.090 ODR for the ES and 0.096 ODR for the rCL1 ELISA. Se of the ES ELISA was 90% and 95% in weeks 4 and 5 pi, respectively, and reached 100% during the period 6-12 weeks pi. Between weeks 13-21 pi Se varied from 90 to 100%. Sp of the ES ELISA was 99.3%. By comparison, calculated rCL1 ELISA Se values were rather low during prepatency (20-85% during weeks 4-7 pi), but increased with early beginning of patency and reached 100% during weeks 10-15 pi. Afterwards, Se ranged between 90% and 100%. With regards to different doses of F. hepatica metacercariae, Spearman rank correlation showed a significant relationship between the infection dose and measured antibody levels for the Pourquier ELISA but not the ES and rCL1 ELISA. Overall, the present study revealed the Pourquier ELISA as the superior test followed by the ES ELISA. Nonetheless, even if rCL1 ELISA was obviously inferior during prepatency, its test parameters associated with patent infections make it a convincing ELISA to diagnose patent fluke infections in cattle.

Bulk milk-estimated seroprevalence of Fasciola hepatica in dairy herds and collecting of risk factor data in East Frisia, northern Germany.

The liver fluke Fasciola (F) hepatica is one of the most important trematodes in cattle farming worldwide. Fasciolosis in dairy cows is leading to production losses due to decreased milk yield, liver condemnation and impaired reproduction. The treatment of dairy cows is unsatisfactory, because available drugs are either effective against adult flukes only or have long withdrawal times or in some countries may not be used at all. In the present study the prevalence of F. hepatica in dairy farms located in East Frisia, which is part of the federal state Lower Saxony, was investigated. East Frisia is considered a high risk area for Fasciola hepatica infections, because of its coastal location, high precipitation and moist pastures. About 750 bulk milk samples were collected in January and November 2006 and analysed for F. hepatica antibodies using the Pourquier ELISA. In addition, questionnaires, which were answered by 260 of the participating farmers, were evaluated to analyse management-related factors associated with fasciolosis. In January and November, 52.1% and 53.6% of the bulk milk samples, respectively, showed positive results. Thereby, 88.1% of the examined farms showed an unchanged infection status, whereas 6.2% of the farms became seropositive during the grazing season and 5.8% of the dairy herds turned seronegative. Statistical analysis revealed a significant negative association between average annual milk production and the frequency of infections with F. hepatica.

Seasonal pattern of Fasciola hepatica antibodies in dairy herds in Northern Germany.

Fasciolosis, caused by the liver fluke Fasciola hepatica, is one of the most important parasitoses in cattle farming worldwide. In dairy cows, the trematode leads to economic losses due to decreased milk yield, a negative impact on reproduction parameters, and liver condemnations. In the present study, the seasonal patterns of F. hepatica antibodies in bulk-tank milk from dairy herds located in East Frisia, a region of the federal state Lower Saxony in the north of Germany, were investigated. This region was chosen since it is known as a high risk area for fluke infections due to its coastal location at the North Sea with the consequence of rather moist pastures. Between 669 and 868 bulk-tank milk samples were collected in January, September and November 2008 and 2010, respectively, and analysed for antibodies against F. hepatica with an in-house ELISA based on excretory-secretory antigens of the liver fluke. The overall East Frisian prevalence was 49.1%, 57.1% and 53.9% in January, September and November 2008 and 45.1%, 49.5% and 48.4% in 2010. From a number of 606 farms, which were sampled in all six investigated months, 34.5% of the farms continued to remain positive, whereas 30.9% continued to remain negative. A percentage of 69.1% (419 farms) were positive on at least one sampling occasion during the study period. The distributions of optical density ratio (ODR) values were skewed to the left but showed a second, lower peak in a high ODR range. Statistical analysis revealed a significant difference concerning the prevalence increase from January to September 2008. Furthermore, the prevalence decrease from September as well as November 2008 to these months in 2010 was significantly different, what might result from a more frequent use of anthelminthics or different climatic conditions.