Excess mortality profile during the Asian genotype chikungunya epidemic in the Dominican Republic, 2014

Background: In 2014 there was a Large chikungunya epidemic in the Dominican Republic, with 539 099 reported cases and 6 deaths. Although chikungunya is considered a Low-mortality disease, studies have suggested this is an underestimation. This study assessed deaths associated with the epidemic. Methods: Mortality data were obtained from the National Statistics Office, the surveillance system for acute febrile illnesses, and the National Epidemiological Surveillance System. Expected all-cause mortality by age group was estimated using the years 2010-2012 as the baseline. The excess deaths were calculated as the difference between observed and expected deaths during the epidemic. Results: The mortality rate increased during the chikungunya epidemic in 2014. There was a strong correlation between monthly excess of deaths and chikungunya cases (Pearson's r=0.89). There was an excess of deaths (>99% confidence interval) among individuals <5 y and >40 y of age. The mortality rates were higher among the elderly. The death excess was 2853. Correcting for the estimated underreporting, there were 4952 deaths during the chikungunya epidemic (49.8 deaths/100 000 population). Conclusion: This study suggests that chikungunya is an important cause of death (underlying or contributing). It is urgent to review clinical protocols and investigate the causes associated with deaths during chikungunya epidemics.