Excess Mortality Related to Chikungunya Epidemics in the Context of Co-circulation of Other Arboviruses in Brazil

Chikungunya is an emerging arbovirus that reached the Western Hemisphere at the end of 2013. Studies conducted in Indie Ocean and India suggest that many of deaths associated with chikungunya cannot be recognized by passive surveillance system. The occurrence of these deaths can be inferred by an increase in the overall mortality observed during chikungunya epidemics. To evaluate the mortality associated with chikungunya epidemics in Brazil, we studied monthly mortality by age group comparing the pre-chikungunya period with the chikungunya epidemic period in the most affected states of Brazil. We obtained official data from National System of Notifiable Diseases (SINAN) and Mortality Information System (SIM), both maintained by the Ministry of Health. It was possible to identify a significant increase in all-cause mortality rate during chikungunya epidemics, there was no similar mortality in previous years, even during dengue epidemics. We estimated an excess of 4,842 deaths in Pernambuco during the chikungunya epidemics (51.4/100,000 inhabitants), the most affected age groups were the elderly and under 1 year of age, the same pattern occurred in all states. Further studies at other sites are needed to confirm the association between increased mortality and chikungunya epidemics. If these findings are confirmed, it will be necessary to revise guidelines to recognize the real mortality associated with chikungunya and to improve therapeutic approaches and protective measures in the most vulnerable groups.