Geospatial distribution of Chikungunya and Zika virus outbreaks in the Dominican Republic: two sides of the same coin?

Abstract

Introduction: Chikungunya and Zika arboviruses caused worldwide outbreaks in 2014 and 2016. Tropical regions played an important role in the distribution of the outbreaks, serving as case exportation platforms for many previously unaffected areas. These viruses managed to cause outbreaks in Dengue-endemic regions where strict-vector control strategies were being implemented. Aim: Our objective is to further identify distribution patterns and important foci for the outbreaks that occurred in 2014 and 2016 of Chikungunya and Zika in the Dominican Republic. Methods: Chikungunya and Zika epidemic periods were identified between February – December 2014 and December 2015 – August 2016. Data was obtained from the Ministry of Health’s obligatory report system pertaining to the municipal residency for each reported case. Percentage of cases were analyzed by provinces at three different points in time, the first being the point at which 10% of the total cases were reported, the second being the point in time with the peak of incidence, and the third being the total incidence number at the end of the epidemic. Results: During the initial stages of both outbreaks, Santo Domingo, its neighboring provinces, and the provinces that border Haiti represented important foci. During the epidemic peak, the main foci of both outbreaks were located in Santo Domingo, its neighboring provinces, and the Dominican Republic’s mountainous region. Total incidence number showed that the main foci for Chikungunya were present in Santo Domingo, its neighboring provinces, and the Dominican Republic’s mountainous region; while Zika had a national distribution, with Santo Domingo serving as the main focus of the 2016 outbreak. Conclusion: Both outbreaks have similar dissemination patterns, which might be influenced by vectorial capacity and distribution, and lack of immunity among large cities. Border provinces and urban areas played a key role in the spread of both outbreaks. Dissemination patterns and other viral endemicity (eg. Dengue) should be further studied with the aim of building preventive strategies. Understanding how new outbreaks occur and spread regarding arboviruses would help shed light on how to develop and improve preventive strategies for the Dominican Republic and other countries that are most vulnerable to epidemics.