Dirofilaria immitis and Dirofilaria striata (Spirurida: Onchocercidae) detected in wild carnivores from Texas, United States

Dirofilaria immitis and Dirofilaria striata (Spirurida: Onchocercidae) are epidemiologically important filarial nematodes detected in wild carnivores sympatric to domestic animals and humans. In this study we surveyed for Dirofilaria species among previous studies archived blood samples (n = 202) of wild carnivores sourced across Texas between the years of 2014-2016 and 2020 to 2023. In total, 117 coyotes (Canis latrans), 67 raccoons (Procyon lotor), 12 gray foxes (Urocyon cinereoargenteus), five bobcats (Lynx rufus), and one striped skunk (Mephitis mephitis) were tested through the amplification of the partial cytochrome oxidase c subunit 1 (COI) gene followed by sequencing. Dirofilaria immitis was detected in 11.39% (95% CI = 7.71-16.51) of the samples (21 coyotes and two raccoons), while D. striata was detected in a single bobcat. Dirofilaria immitis sequences had 99.85%-100% (99.92% ± 0.08) similarity with other D. immitis sequences in GenBank. The sequence of D. striata from the bobcat was 100% similar to the single COI sequence available in GenBank. Data from this study reinforce the role of coyotes as a wild reservoir for D. immitis and suggest that raccoons may also play a role in the epidemiology of this parasite. This study additionally provides molecular data on D. striata, an understudied filarioid of felids.