AfroColombian ethnicity, a paradoxical protective factor against Dengue.

Introduction: Dengue is a priority public health problem. During epidemics in Cuba and Haiti, ethnic African descendents population had lower risk of dengue, and ethnic was proposed as a protective factor. Objective: To determine the relation between the cumulative incidence of dengue and the proportion of Afro-Colombians in communities of Cali, during the epidemic of 2013. Methods: This study was conducted in Cali, Colombia. The design was ecological, using information from the National Census 2005 projected to 2013, from the National Administrative Department of Statistics (DANE), and the National Epidemiological Surveillance System. It was obtained the Pearson's correlation coefficient between cumulative incidence and the proportion of Afro-Colombians population by communities; additionally it were evaluated the cummulatives incidences of two zones with different proportion Afro-Colombians inhabitants. The Association was evaluated for aggregation bias, confounding by social variables, and interaction by area of residence, too. Results: Dengue cumulative incidence was significantly lower for AfroColombian, regardless of the proportion of Afro-Colombians population in the area of residence. The Relative Risk of dengue between non-Afro-Colombians and Afro-Colombians was 9.4 (95% CI= 8.4-10.6) in the high proportion zone of Afro-Colombians population, while the Relative Risk in the low proportion zone of Afro-Colombians population was 4.0 (95% CI= 3.6-4.4). There was no evidence of aggregation bias or confounding in the association by social variables. Conclusions: The Afro-Colombians population had a significantly lower risk of getting dengue and its complications, compared with the non-Afro-Colombians population. The non-Afro-Colombians populations living in areas with a high proportion of Afro-Colombians increase their risk of dengue more than double, suggesting an asymptomatic viremic environment.