CONICET | Buscador de Institutos y Recursos Humanos

Many species of Amblyomma ticks are commonly found infesting wild birds in South America, where birdsare important hosts for several arboviruses, such as West Nile virus (WNV) and Saint Louis encephalitis virus (SLEV). In thisstudy, WNV and SLEV transmission experiments were performed to evaluate the vector competence of three SouthAmerican tick species: Amblyomma ovale, Amblyomma tigrinum, and Amblyomma tonelliae. Larval and nymphal ticks ofeach species were allowed to feed on chicks needle inoculated with WNV or SLEV. All threeAmblyomma species acquiredeither WNV or SLEV through larval feeding, with infection rates varying from 3.1% to 100% for WNV and from 0% to 35.7%for SLEV in engorged larvae. Transstadial perpetuation of the viruses was demonstrated in the molted nymphs, with WNVinfection rates varying from 0% to 33.7% and SLEV infection rates from 13.6% to 23.8%. Although nymphal ticks alsoacquired either virus through feeding, transstadial perpetuation to adult ticks was lower, with virus detection in only 3.2%of A. tigrinum and 11.5% of A. tonelliae unfed adult ticks. On the other hand, vector competence for nymphs (exposed toWNV or SLEV through larval feeding) and adult ticks (exposed to WNV or SLEV through larval or nymphal feeding) was nullin all cases. Although our results indicate transstadial perpetuation of WNV or SLEV in the three tick species, the ticks werenot competent to transmit these agents to susceptible hosts. The role of these ixodid tick species in the epidemiology ofWNV and SLEV might be insignificant, even though at leastA. ovale andA. tigrinum are frequent bird ticks in Latin America,so the virus could survive winter in the fed larvae. However, future studies are required to determine the implications thatthis could have, as well as analyze the vector competence of other common bird tick species in South America.