Asynchronicity of endemic and emerging mosquito-borne disease outbreaks in the Dominican Republic

Petrone, M. E.; Earnest, R.; Lourenco, J.; Kraemer, M. U. G.; Paulino-Ramirez, R.; Grubaugh, N. D.; Tapia, L.

Mosquito-borne viruses pose a perpetual public health threat to countries and territories in the Carribean due to the region's tropical climate and seasonal reception of international tourists. Outbreaks of the emerging viruses chikungunya and Zika in 2014 and 2016, respectively, demonstrated the rapidity with which these viruses can spread between islands. At the same time, the number of reported dengue fever cases, caused by the endemic dengue virus, has steadily climbed over the past decade, and a large dengue outbreak that began sweeping through this region in 2019 continues in 2020. Sustainable disease and mosquito control measures are urgently needed to quell virus transmission in the long term and prevent future outbreaks from occurring. To improve upon current surveillance methods, we analyzed temporal and spatial patterns of chikungunya, Zika, and dengue outbreaks reported in the Dominican Republic between 2012 and 2018. The viruses that caused these outbreaks are transmitted by Aedes mosquitoes, which are sensitive to seasonal climatological variability. In this study, we evaluated whether climate and the spatio-temporal dynamics of past dengue outbreaks could inform when and where future emerging disease outbreaks might occur. We found that the temporal and spatial distribution of emerging disease outbreaks did not conform to those of seasonal dengue outbreaks. Rather, the former occurred when climatological conditions were suboptimal for Aedes activity. Provincial dengue attack rates did not correspond to those of emerging diseases. Our study also provides evidence for under-reporting of dengue cases, especially following the 2016 Zika outbreak. We advocate for the implementation of a sustainable and long-term surveillance system to monitor the spread of known mosquito-borne viruses and to identify emerging threats before they cause outbreaks. Specifically, we recommend the use of febrile illness incidence, case fatality rates, and serosurveys during inter-outbreak periods to better understand rates of transmission and asymptomatic infection.