New insights into the epidemiology of liver fluke

University College Dublin has recently published an article entitled “Validation of a spatial liver fluke model under field conditions in Ireland” in conjunction with Teagasc AGRIC and The Centre for Veterinary Epidemiology and Risk Analysis (CVERA).

UCD Team

UCD Team

This study aimed to validate and improve previously published maps for predicting the presence of liver fluke by using a more inclusive and spatially widespread exposure dataset. Results from this analysis will be invaluable to improve risk predictions and future control measures. They will also be very useful for establishing spatial relationships between fasciolosis and other important livestock diseases which, due to immunomodulatory effects of fasciolosis, may be affected by concurrent infections. This has been shown to be the case in bovine TB (Claridge et al., 2012) and is suspected to play a role in related diseases such as Johne’s disease (Lucena et al., 2017).

Live Fluke

Liver Fluke

By using data for F. hepatica exposure from in 312 dairy herds, 194 beef herds and 290 sheep flocks, we validated the theoretical baseline maps previously published for liver fluke in Ireland (Selemetas et al., 2015a, 2015b; Selemetas and de Waal, 2015) by three approaches; i) comparison of the original predicted and actual exposure; ii) comparison of original and actual cluster distribution of hotspots and coldspots; and iii) development of a new predictive model including a wider range of predictors. We determined that the previous predictive model had a sensitivity of 94.7%, a specificity of 5%, a positive predictive value of 60% and a negative predictive value of 38.2%. Moreover, we identified new hotspots of liver fluke exposure, and vegetation as an additional risk factor to the ones identified previously (rainfall and temperature), which we suggest could be employed as a predictor for future forecasting. The article can be freely downloaded via the following link:

Claridge, J., Diggle, P., McCann, C. M., Mulcahy, G., Flynn, R., McNair, J., Strain, S., Welsh, M., Baylis, M., Williams, D. J. (2012). Fasciola hepatica is associated with failure to detect bovine tuberculosis in dairy cattle. Nature Communications, 3, 853.
Lucena, A.N., Cuartero, L.G., Mulcahy, G., & Zintl, A. (2017). The immunoreg- ulatory effects of co-infection with Fasciola hepatica: From bovine tuber- culosis to Johne’s disease. The Veterinary Journal, 222,9–16
Selemetas, N., de Waal, T., 2015. Detection of major climatic and environmental predictors of liver fluke exposure risk in Ireland using spatial cluster analysis. Veterinary Parasitology. 209, 242–253.

Selemetas, N., Ducheyne, E., Phelan, P., O’Kiely, P., Hendrickx, G., de Waal, T., Kiely, P.O., Hendrickx, G., 2015a. Spatial analysis and risk mapping of Fasciola hepatica infection in dairy herds in Ireland. Geospatial Health 9, 281–291.

Selemetas, N., Phelan, P., O’Kiely, P., de Waal, T., 2015b. Cluster analysis of fasciolosis in dairy cow herds in Munster province of Ireland and detection of major climatic and environmental predictors of the exposure risk. Geospatial Health 9, 271–9.