First detection and characterisation of Eimeria zaria in European chickens

The global poultry industry has experienced dramatic growth in recent decades, increasing the significance of pathogens of chickens. Protozoan parasites of the genus Eimeria can cause the disease coccidiosis, compromising animal health and welfare, and incurring significant annual costs. Seven Eimeria species have long been recognised to infect chickens, supplemented by three new candidate species first reported from Australia in 2007/8. Named Eimeria lata, Eimeria nagambie and Eimeria zaria, one or more of these new species have been reported in Australia, several countries in sub-Saharan Africa, India, Venezuela, and most recently the United States of America, but none have been detected in Europe. Here, a panel of 56 unvaccinated broiler chicken farms were sampled in the final week of production from France, Greece, Italy, the Netherlands, the Republic of Ireland, and the United Kingdom to assess the occurrence of all ten Eimeria species using specific polymerase chain reaction (PCR). Overall, 39 of 56 (69.6%) farms were found to host at least one species. Eimeria acervulina, E. tenella, and E. maxima were most common, with E. mitis and E. praecox also widespread. Eimeria necatrix was detected on one farm in France, while E. brunetti was not detected. Eimeria zaria was detected for the first time in Europe, appearing in Greece and Italy (one occurrence each). New primers were designed to confirm detection of E. zaria and provide template for phylogenetic comparison with the reference isolate from Australia. Detection of E. zaria in Europe reinforces the importance of integrated control for coccidiosis given the lack of protection induced by current anticoccidial vaccines.