Changing dynamics of Aedes aegypti invasion and vector-borne disease risk for rural communities in the Peruvian Amazon
Aedes aegypti, the primary vector of dengue virus, is predominantly considered an urban mosquito, especially in the Americas, where its reemergence began in cities after the end of continent-wide eradication campaigns. The results of our study diverge from this narrative, demonstrating the recent and widespread rural invasion of Ae. aegypti along major shipping routes in the northern Peruvian Amazon between the major cities of Iquitos, Pucallpa, and Yurimaguas. We identified Ae. aegypti populations in 29 of 30 sites surveyed across a rural to urban gradient and characterized mosquito larval habitats and Ae. aegypti adult metrics. Households, regardless of community size, were more likely to be positive for Ae. aegypti adult(s) and had a higher number of Ae. aegypti adults if a mosquito larval habitat was identified on the property, compared to houses without a larval habitat. In multiple instances, adult Ae. aegypti indices in rural villages were equal to or greater than indices in dengue-endemic cities, suggesting the entomological risk level in some rural areas is sufficient to sustain dengue transmission. Fourteen rural sites were sampled in transects from the community river port into town. In seven of these sites, houses closer to the port were significantly more likely to be infested with Ae. aegypti adults than houses further from the ports, and four additional sites had a marginal relationship to the same effect. This pattern suggests that many rural sites are invaded via adult Ae. aegypti disembarking from boats at the port, finding nearby oviposition sites, and advancing stepwise into town. The existence of the pattern also suggests that many of the sites are still experiencing active invasion, with sections of towns still Ae. aegypti-free. Only one site shows a strong signal of invasion via the egg or larval stage, with a focus of Ae. aegypti far removed from the port. The widespread infestation of Ae. aegypti in rural areas is a major public health threat given the far distance of communities to hospital care. It is important to implement control measures now before the mosquito gains a stronger foothold in zones of active invasion.