Co-occurrence of Eutrombicula alfreddugesi and Oswaldofilaria chabaudi in Tropidurus torquatus and first report of microfilariae in the chigger mite: possible evidence of a lifecycle pathway?

While much attention has been paid to vector-borne filariasis, diseases that threaten millions of people in tropical and subtropical countries, the literature on host-parasite associations and transmission strategies of filarial nematodes in wildlife is scarce. Here, we report the co-occurrence of chigger mites (Eutrombicula alfreddugesi) and onchocercid nematodes (Oswaldofilaria chabaudi) parasitizing the lizard Tropidurus torquatus in the State of Minas Gerais, Brazil. Examination of chiggers established, for the first time, the occurrence of microfilariae in trombiculid mites (Trombiculidae). These larvae were morphologically similar to those recovered from adult females of O. chabaudi. The current evidence suggests that chiggers do not play a role in the transmission of filarioid nematodes, but rather act as accidental or dead-end hosts. Nevertheless, considering the polyphagous nature of trombiculid mites, similar to blood-sucking insects involved in the transmission of several infectious diseases, further studies may shed light on the potential role of chiggers as vectors of filarioids.