UC Davis

House mice (Mus musculus) are prolific transmitters of pathogens and parasites to naïve populations of wildlife. We studied a community in which house mice are increasingly abundant in rare desert marsh habitat occupied by the endangered Amargosa vole (Microtus californicus scirpensis). In this study, house mice in the Amargosa Basin were identified as hosts of Protospirura sp., a stomach nematode of rodents. During field surveys in 2022 and 2023, 59 house mice and one wild Amargosa vole were collected from endangered vole habitat in Tecopa, California. Nematode prevalence varied by organ; three of 35 (8.6%) mouse intestines and 11 of 59 (18.6%) mouse stomachs were infected. Morphology was used to identify nematodes collected from the house mouse intestines. PCR and DNA sequencing of nematodes from mouse stomachs were confirmed to be Protospirura sp. Marsh location, body condition score, sex, and body mass were assessed as host risk factors, but were not significantly correlated with nematode infections in this investigation. The wild vole was infected with Strongyloides sp. This study identifies house mice as hosts of parasitic nematodes that may spill over into the endangered Amargosa vole population.