Prevalence, risk factors and spatial analysis of liver fluke infections in Danish cattle herds

Abstract

BackgroundFasciola hepatica, a trematode parasite (liver fluke), infects a wide range of host species causing fasciolosis. The disease is prevalent world-wide and causes considerable economic losses to the livestock industry. Fasciolosis is regarded as an emerging food-borne zoonosis. To promote awareness among farmers and to implement strategies to control the infection, this study examined the prevalence, spatial distribution and risk factors for F. hepatica infection in Danish cattle herds.MethodsA retrospective population based study was performed using meat inspection data of approximately 1.5 million cattle slaughtered in the period 2011 to 2013. Annual cumulative prevalence of recorded liver fluke findings was calculated for each year. Global and local spatial cluster analysis was used to identify and map spatial patterns of F. hepatica positive and negative herds to explore environmental indicators of infection. Herd level, trade and environmental risk factors were evaluated for association with infection using logistic regression. Herd infection status as predicted from the final risk factor model was compared with the observed status using heat maps to assess how well the model fitted the observed spatial pattern.ResultsDuring the investigated period (2011–2013), an increase in annual herd prevalence was noted (2011–25.6%; 2012–28.4%; 2013–29.3%). The spatial analysis suggested significant clustering of positive and negative herds. Presence of streams, wetlands and pastures on farms showed a significant association with the presence of infection in cattle herds. Buying animals from positive herds was a risk factor on conventional farms. Additionally, risk of being infected with F. hepatica was higher in non-dairy herds of medium size (≥30 and < 100) when compared to dairy and large (≥100) cattle herds. The observed spatial pattern could be reproduced by predictions of the risk factor model.ConclusionsThis study showed an increase in annual herd level prevalence (2011 to 2013) indicating that an increasing proportion of herds are infected with F. hepatica infection every year in Denmark. Fasciolosis was found to be associated with both herd and environmental factors where the infection was influenced by local factors that clustered geographically.

Herd-level prevalence of selected endemic infectious diseases of dairy cows in Great Britain

“…The estimated prevalence values of most of the studied pathogens broadly agree with those reported from other countries, where these pathogens are considered endemic, suggesting similar pathogen dynamics [BVDV and BHV-1 (Kampa et al., 2004;Sayers et al, 2015;Fernandes et al, 2016), MAP (Muskens et al, 2000;van Schaik et al, 2003), C. burnetii (van Engelen et al, 2014), Salmonella spp., and Leptospira Hardjo (Habing et al, 2012;O'Doherty et al, 2013). Higher-prevalence estimates of F. hepatica (Cringoli et al, 2002;Olsen et al, 2015) and N. caninum infections were estimated in our study compared with some other countries (Sanderson et al, 2000;O'Doherty et al, 2013).Bulk milk samples were used to assess herd status based on the presence of specific antibodies or antigen. Our prevalence estimates are therefore herd-level estimates and they are subject to misclassification bias as a result of imperfect Se or Sp of the tests applied at the level of the herd.…”

Wat zijn de mogelijkheden om een leverbotinfectie van melkvee te voorkomen?

“…Het aantal geïnfecteerde melkveebedrijven lijkt in andere landen toe te nemen (Fairweather, 2011;Fitzpatrick, 2013;KnubbenSchweizer & Torgerson, 2015;Olsen et al, 2015;Selemetas et al, 2015b). De prevalentie van leverbot in Nederland wordt niet gemonitord (buiten de gegevens die zijn verkregen van bedrijven die deelnamen aan GD tankmelkonderzoek) waardoor onbekend is of in Nederland eveneens sprake is van een toename in leverbot.…”

“…Daarnaast kan de manier waarop veehouders omgaan met infectierisico's invloed hebben op de prevalentie. Zo is insleep van infectie mogelijk via aangekocht geïnfecteerd vee en levert het weiden in natte gebieden een hoger risico op (Olsen et al, 2015).…”

“…Helaas wordt vaak niet de reden van afkeur gespecificeerd en doorgegeven aan de veehouder. In bijvoorbeeld Denemarken wordt de reden van afkeur van de levers wel geregistreerd (Olsen et al, 2015).…”

Study on Prevalence of Fascioliasis in Ruminants in Dasht Room County in Spring and Summer of 2013

“…In domestic ruminants, adverse effects of acute or chronic fasciolosis include decreased meat and milk production, decreased fertility, and increased veterinary costs [14]. Fasciolosis is one of the big and most important worldwide problems mainly due to mortality of animals, cost of diagnosis, and treatment of condemned liver and it reduces milk and meat production [15,16], fertility disorder, and drug resistance against fasciolosis [17]. Fasciolosis is estimated to be responsible for the annual loss of thousands of dollars in the Iranian agricultural industries.…”