What were the key findings of the GLOWORM project regarding the distribution of Haemonchus contortus in Europe?

The GLOWORM project, conducted across Ireland, Switzerland, and Italy, revealed significant variations in Haemonchus contortus prevalence. Switzerland and Italy showed high prevalence rates (77% and 73%, respectively), while Ireland had a significantly lower rate of 4%. Spatial analysis indicated a north-south gradient, suggesting climatic factors like temperature and rainfall influence the parasite's spread. Seasonality and annual cyclicity were also identified as important factors, particularly in southern Italy. Mean temperature and rainfall were dominant factors driving variations in prevalence between countries.

How did the GLOWORM project assess the prevalence of Haemonchus contortus in sheep farms?

The GLOWORM project utilized a standardized approach to assess Haemonchus contortus prevalence. Two consecutive field surveys were conducted during August-October in 2012 and 2013. A total of 259 sheep farms were examined using harmonized diagnostic procedures. These procedures included pooled fecal samples, the FLOTAC technique, and coproculture. This rigorous methodology allowed researchers to accurately identify and quantify Haemonchus contortus infections across the study areas.

What practical steps can sheep farmers take to protect their flocks from Haemonchus contortus infections, according to the study?

Based on the findings, sheep farmers can implement targeted control strategies. This includes optimizing grazing management to minimize parasite exposure, using strategic anthelmintic treatments to prevent and control infections, and considering climate-smart farming practices. These practices help mitigate the impact of environmental factors, such as temperature and rainfall, on parasite transmission and reduce the overall risk to the flock.

What is the significance of understanding the spatial distribution of Haemonchus contortus for sheep farmers?

Understanding the spatial distribution of Haemonchus contortus, as highlighted by the GLOWORM project, is crucial for sheep farmers because it allows for the implementation of targeted control strategies. By knowing where the parasite is most prevalent and the environmental factors that influence its spread, farmers can make informed decisions regarding grazing practices, anthelmintic use, and overall farm management. This knowledge helps minimize economic losses from reduced productivity and improve animal welfare by effectively managing the risk of Haemonchus contortus infections.

Sheep grazing on a farm in Europe, with a heat map overlay showing parasite risk.

Is Your Sheep Farm at Risk? Understanding Haemonchus Contortus in Europe

Q: What is Haemonchus contortus, and why is it a major concern for sheep farmers in Europe?

Haemonchus contortus is a blood-feeding parasite, a type of gastrointestinal (GI) strongyle that significantly threatens sheep farms in Europe. It causes anemia, reduces productivity, and can lead to death in severe cases. The parasite's ability to develop resistance to common anthelmintic drugs complicates its management, making it a critical concern for both farmers and veterinarians. This parasite is a major driver of economic losses and compromises animal welfare, making its control essential for the livestock industry.

Theo Raines in Health & Wellness December 2025 • 4 min read.

"A comprehensive look at the spatial distribution and risk factors of Haemonchus contortus, a major parasitic threat to sheep farms across Europe, and what you can do to protect your flock."

Parasitic infections in ruminants, particularly those caused by gastrointestinal (GI) strongyles like Haemonchus, Ostertagia, and Trichostrongylus, pose a significant and ongoing threat to the livestock industry in Europe. These infections lead to substantial economic losses and compromise animal welfare, making their control a critical concern for farmers and veterinarians alike.

Among these GI strongyles, Haemonchus contortus stands out as a particularly virulent species affecting sheep. This blood-feeding parasite causes anemia, reduced productivity, and even death in severe cases. Its ability to develop resistance to common anthelmintic drugs further complicates management efforts, necessitating a deeper understanding of its prevalence and distribution.

To address this challenge, a collaborative study was conducted across three key European regions—Ireland, Switzerland, and Italy—as part of the EU-funded GLOWORM project. This research aimed to map the spatial distribution of H. contortus and identify the environmental and climatic factors influencing its spread, providing valuable insights for targeted control strategies.

Mapping the Threat: Understanding Haemonchus Contortus Distribution

Sheep grazing on a farm in Europe, with a heat map overlay showing parasite risk.

The GLOWORM project employed a standardized approach to assess H. contortus prevalence in sheep farms across Ireland, Switzerland, and Italy. Two consecutive field surveys were conducted during the August-October periods of 2012 and 2013. In total, 259 sheep farms were examined using harmonized diagnostic procedures, including pooled fecal samples, the FLOTAC technique, and coproculture.

This rigorous methodology allowed researchers to accurately identify and quantify H. contortus infections across the study areas. The georeferenced parasitological data were then analyzed using a Bayesian geostatistical model, which accounted for preferential sampling and incorporated climatic and environmental covariates to provide a comprehensive understanding of the parasite's distribution.

Key findings from the study revealed significant variations in H. contortus prevalence across the three countries:

Switzerland: Showed a high prevalence of 77%.
Italy: Also exhibited a high prevalence of 73%.
Ireland: Displayed a significantly lower prevalence of only 4%.

Spatial analysis further revealed distinct patterns of H. contortus distribution in Switzerland and Italy, with a noticeable north-south gradient. This suggests that climatic factors, such as temperature and rainfall, play a crucial role in the parasite's prevalence.

The study also highlighted the importance of seasonality and annual cyclicity within each country, particularly in southern Italy, where these factors significantly influenced H. contortus infection rates. Furthermore, mean temperature and rainfall were identified as dominant factors driving variations in prevalence between countries.

Protecting Your Flock: Practical Implications for Sheep Farmers

The findings from the GLOWORM project offer valuable insights for sheep farmers and veterinarians seeking to manage and control H. contortus infections. By understanding the spatial distribution and key drivers of parasite prevalence, targeted control strategies can be implemented to minimize economic losses and improve animal welfare. This includes optimizing grazing management, strategic anthelmintic use, and considering climate-smart farming practices to mitigate the impact of environmental factors on parasite transmission.