New Insights into Morphological and Biological Features of Capillaria aerophila (Trichocephalida, Trichuridae) S97 Donato Traversa 1 (*), Angela Di Cesare 1 , Riccardo P. Lia 2 , Giuseppe Castagna 1 , Silvana Meloni 1 , Josef Heine 3 , Katrin Strube 3 , Piermarino Milillo 1 , Domenico Otranto 2 , Oliver Meckes 4 , Roland Schaper 3 1 Department of Comparative Biomedical Sciences, Faculty of Veterinary Medicine, Teramo, Italy 2 Department of Veterinary Public Health and Animal Sciences, Faculty of Veterinary Medicine, Bari, Italy 3 Bayer Animal Health GmbH, Germany 4 Eye of Science, Germany * E-mail: dtraversa@unite.it Parasitol Res (2011) 109:S97 – S104 DOI 10.1007/s00436-011-2406-4 Abstract Capillaria aerophila is a trichuroid nematode affect- ing the respiratory system of dogs, cats, wild carni- vores and, occasionally, humans. Animals become infected by ingesting larvated eggs or earthworms, which act as facultative intermediate hosts. The aim of this work is to present new insights into mor- phological and biological features of this neglected lungworm. Typical features of C. aerophila eggs, differentiating them from those of most known tri- churoid whipworms (i.e. size, asymmetry of bipolar plugs and a wall with a network of anastomosing ridges), were detected upon light and scanning electron microscopy. Eggs of C. aerophila were used for in vitro development. Light microscopy showed typical features of C. aerophila eggs: size, asymme- try of bipolar plugs and a wall with a network of anastomosing ridges. All these features were con- irmed upon SEM, in that C. aerophila eggs showed an outer densely striated and net-like shell. Eggs of T. vulpis, used for a comparative analysis, were bigger than those of C. aerophila and showed a thick and smooth wall at both light and scanning electron microscopy. Eggs started to develop after 35 days from shedding and mobile larvae were observed in the eggs after two months. The results of this study provide key information on the biological cycle of C. aerophila and present key morphological charac- ters for the identiication of eggs in faeces.