Assessing arboviral circulation in Aedes mosquito vectors in Posadas, Argentina

FAY J.; LITWINIUK S.; LOPEZ K; GONZALES C; SANDER B; BOAGLIO V.; GAUTO N; ZELAYA F.; CEBALLOSO V; FERRERAS J.; VICENTE J.; CARISSIMO C; TALBOT; KULKARNI M; MIRETTI M.

Jornada; American Society of Tropical Medicine and Hygiene 2021 Annual Meeting; 2021

American Society of Tropical Medicine and Hygiene

Zika, dengue and chikungunya viruses (Flaviviridae: DENV, ZIKV; Togaviridae: CHIKV) are transmitted by a common mosquito vector (Aedes aegypti) to the human host, causing recurrent epidemics and inflicting a huge burden in public health. While DENV has triggered major epidemic outbreaks in Argentina, ZIKV infections have been limited to few clinically diagnosed cases. The lack of systematic surveillance for arbovirus circulation in patients and adult mosquitos does not rule out the presence of another arbovirus. Early detection of viral circulation in the Aedes vector is a tool for epidemic prevention and mitigation. In this work we aim to investigate the presence of ZIKV, DENV and CHIKV (ZDC) in Aedes females collected in Posadas, Argentina, during the 2019/2020 dengue epidemics. We used two surveying strategies: (1) a longitudinal year-long (2019) fortnight samplingin selected 32 houses per month (total 384 houses) in four neighbourhoods using four different typesof mosquito traps; and (2) collecting mosquitoes in houses of reported febrile patients (2019-2020). Total RNA extracted from mosquito pools was subjected to one-step RT qPCR to detect the presence of ZDC viruses in multiplex reactions. Dengue positive pools were assayed with the CDC DENV1-4RTPCR assay to determine the viral serotype. After testing 381 fed female Ae. aegypti, we found dengue infected fed females in only 3 mosquito pools captured in premises of febrile patients, but none in females from the longitudinal setting in 4 neighbourhoods. The DENV(+) Aedes pools were collected in reported dengue-suspect houses where dengue infections were not actually confirmed(patient´s blood samples not available or absence of fever). Zika and chikungunya viral RNA was not detected in any sample. This study shows the contribution of adult mosquito monitoring to real-time arboviral circulation surveillance. More extensive studies are required to evaluate its implementationcost-effectiveness, including how it correlates with the distribution of DENV(+) cases, and its relative contribution to corroborate dengue infection sources