A Cross-Sectional Household Survey in the US Virgin Islands (2019) Reveals Cisterns as Challenging Peridomestic Aedes aegypti Habitats.

Most residences in the United States Virgin Islands (USVI) rely on household rainwater-catchment systems and subterranean cisterns for long-term water storage that may provide suitable habitats for mosquitoes of public health relevance. We conducted a household cistern survey (n = 164) on the islands of St. Croix, St. John, and St. Thomas in 2019. The survey revealed that 45.7% (95% CI: 38.3-53.4%) of cisterns contained mosquitoes (adult and/or immature mosquitoes). Aedes aegypti, a vector of chikungunya, dengue, and Zika viruses in the USVI, was found in 27.4% (95% CI: 21.2-34.7%) of cisterns and accounted for 83.3% of the total mosquitoes identified in the study. The odds of detecting mosquitoes in a cistern were 5.45 times higher at locations where the residents reported that they had observed adult mosquitoes coming out of their cisterns (95% CI: 2.25-14.21), suggesting that vector control personnel should consider resident complaints about mosquitoes in their cistern as valid and likely reliable self-assessments. Resident mosquito management practices in cisterns did not correspond with decreased odds of mosquito detection. We conclude that cisterns in the USVI commonly provide habitat for immature and adult Ae. aegypti, which may decrease the effectiveness of area-wide mosquito control strategies. Additional studies are necessary to evaluate the importance of these cisterns as they relate to mosquito production and arbovirus transmission risk, and to assess physical and chemical control methods.