Occurrence of Eucoleus aerophilus in wild and domestic animals: a systematic review and meta-analysis

Background Eucoleus aerophilus (syn. Capillaria aerophila ) is a nematode with a worldwide geographical distribution. It causes a disease called lung capillariosis by affecting the respiratory tract of wild and domestic animals, and has also occasionally been described in humans. Despite steady increases in knowledge of the morphology of this neglected parasite, many aspects are still poorly understood. Epidemiological data regarding, for example, geographic distribution, range of hosts, clinical relevance and the actual zoonotic potential of this nematode are scarce and incomplete. Methods This article is a systematic review based on the screening of three databases (PubMed, Web of Science and Science Direct) to identify eligible studies published from 1973 to the end of 2022. Results From a total of 606 studies describing the occurrence of E. aerophilus , 141 articles from 38 countries worldwide were included in this meta-analysis, all of which presented results obtained mainly with flotation and necropsy. Due to the occurrence of E. aerophilus in many different species and different matrices (lungs and faeces), we decided to conduct the meta-analysis separately for each species with a given matrix. This systematic review confirmed the status of the Red fox as the main reservoir and main transmitter of E. aerophilus (average prevalence of 43% in faeces and 49% in lungs) and provided evidence of a higher prevalence of E. aerophilus in wild animals in comparison to domestic animals, such as dogs (3% in faeces) and cats (2% in faeces and 8% in lungs). Previous studies have investigated many host-related factors (age, sex, environmental/living conditions) in relation to the prevalence of E. aerophilus , but they show wide variations and no simple relationship has been demonstrates. Furthermore, mixed infections with other pulmonary nematodes, such as Crenosoma vulpis and/or Angiostrongylus vasorum , are reported very frequently, which greatly complicates the diagnosis. Conclusions This systematic review focused on identifying data gaps and promoting future research directions in this area. To the best of our knowledge, this is the first systematic review that evaluates and summarizes existing knowledge on the occurrence and prevalence of E. aerophilus in wild and domestic animals originating from different geographical locations worldwide. Graphical Abstract