Entomo-Molecular and Epidemiological Survey of Arboviruses in Aedes (Stegomyia) aegypti Mosquito Populations and Dengue Seroprevalence Among Migrants in Reynosa, a City on the US-Mexico Border.

Abstract

Background: Border regions such as the US-Mexico border may be particularly vulnerable to dengue emergence and re-emergence due to high human mobility, cross-border movement, and favorable conditions for Aedes mosquitoes.

Methods: We investigated dengue and other arboviruses in mosquito vectors, and dengue seroprevalence among migrants residing in camps in Reynosa, Mexico, between October 2019 and November 2022. Entomological surveillance was conducted in two phases using BG-Sentinel traps, CDC backpack aspirators, Autocidal Gravid Ovitraps, and resting boxes. Mosquito trapping was done twice a week with an interval of 3 days between each trapping. Mosquito samples were tested by RT-PCR for dengue, chikungunya, and Zika viruses, while migrant blood samples were screened for anti-dengue IgM antibodies using ELISA.

Results: In the first phase, 2263 mosquitoes were collected, including 456 females Aedes aegypti grouped into 42 pools; three pools were positive for DENV-2 while none were positive for DENV-1, DENV-3, DENV-4, chikungunya virus, or Zika virus. During the second phase, 1713 mosquitoes were collected, including 179 female A. aegypti grouped into 14 pools, with one pool positive for dengue virus and none positive for chikungunya or Zika viruses. Among the 95 migrant serum samples analyzed, four were positive for anti-DENV IgM, yielding a seroprevalence of 4.2% (95% CI: 1.2-10.4%). Participants reported frequent mosquito exposure and general awareness of mosquitoes, although knowledge of mosquito-borne arboviruses and preventive practices remained limited. IgM-seropositive participants were less likely to report mosquito contact in their country of origin than seronegative individuals (0% vs. 67.8%; p = 0.013), which may suggest local exposure, though IgM serology cannot determine the timing or location of infection.

Conclusion: These findings highlight the need for strengthened vector control and arboviral surveillance in Reynosa, both to reduce local transmission and to mitigate the risk of cross-border spread.