Extension of the Avian Host Range of Collyriclosis in Europe

Abstract

We describe cases of collyriclosis in apodiform and passeriform birds in Portugal, Switzerland, and Germany. We extend the host range of Collyriculm faba to include apodiform birds ( Apus apus , Apus melba , and Apus pallidus ) and the passerine Sitta europaea (Eurasian Nuthatch). Infections varied in severity from an incidental finding to severe debilitation and death. The infection route remains unclear with the apparent absence from Germany, Portugal, and Switzerland of the first intermediate host of C. faba, the aquatic gastropod Bythinella austriaca, implying that other organisms might be involved in the parasite's life cycle. Furthermore, the detection of C. faba cysts in very young passerine birds may indicate an infection during the nestling stage and a rapid development of parasite-containing subcutaneous cysts. This series of cases highlights an increased geographic range into Portugal and the potential debilitating nature of a parasite of migratory birds in Europe. However, given the rarity of cases, collyriclosis does not seem to present an important threat to migratory species preservation.