Risk of urban Mayaro virus (Alphavirus: Togaviridae) transmission: isAedes aegyptia competent vector?

Abstract

SummaryMayaro virus (MAYV) is an emerging pathogen endemic in Latin America and is the causative agent of fever and polyarthritis. Urban transmission depends on its ability to be transmitted byAedes aegyptiand to be amplified by humans. The aim of this study was to evaluate the susceptibility to infection and transmission and the presence of barriers to infection in different populations ofAe. aegyptifor MAYV.Ae. aegyptieggs were collected from Córdoba, Buenos Aires and Rosario Cities (Argentina). Females were infected with five viral loads of MAYV strain (1 to 6 log10PFU/ml) and maintained for 8 days. The presence of infectious viral particles in body, legs, and saliva was detected by plaquing assay in Vero cell monolayers. Through a bibliographic search,Ae. aegyptipopulation data from Perú were incorporated and tested with different viral doses of MAYV. We build dose-response curves forAe. aegyptipopulations to estimate infection (IR), dissemination (DR) and transmission (TR) based on MAYV viral loads detected in humans to estimate transmission risk occurring in an urban environment. The overall IR and DR were significantly associated with the viral doses and were not significantly affected by population origin. We found IR ranging for 3 to 84% (ID50% were higher than 5.5 log10PFU/ml) and a DR reached 78% (DD50% higher than 6.0 log10PFU/ml). The percentage of dissemination based on the infected mosquitoes ranged from 60 to 86% while the percentage of transmission based on disseminated mosquitoes ranged from 11 to 60%. Our results indicate thatAe. aegyptipopulations are not competent vectors for MAYV because they need higher viral doses than those developed by humans (3.9 – 4.5 log10PFU/ml) to become infected. Only a very low proportion of infected mosquitoes with high 5 log10PFU/ml are capable of transmitting it.