Abstract

Background: During 2005-2006, chikungunya (CHIK) emerged as a large epidemic in Reunion Island, infecting approximately one third of the population. This study aimed to assess the long term impact of this outbreak by estimation of the progression of chronic patients over time and calculate the global burden of CHIK in Reunion Island with the Disability Adjusted Life Years (DALY) method.

Methods: To estimate the proportion of chronic patients over time, the data of 8 publications were used in a multivariate linear regression model adjusted on patients’ age after the review of more than 50. The selection criteria were: cohort studies studying the persistence of post-epidemic symptoms based on CHIK epidemics located in the Indian Ocean Territories since 2006. These estimations were used for the calculation of years lived with disabilities (YLD) in DALY. As well, as no disability weight has been estimated for CHIK by the global burden disease group of WHO, the disability weights of dengue were used for the acute phase and of rheumatoid arthritis for the chronic phase to weight YLD. To take into account variations in the parameters of YLD, DALY was simulated 1000 times using the Monte Carlo technique.

Results: The regression model estimated that 58.3% (CI: 51.2-65.3%) of the patients were still symptomatic after 1 year and 0% (CI: 0.0-15.2%) after 5 years. In average, the global disease burden was 65-73 DALY/1000 persons, 55.5% concerning the active population (20-60 years old), and 86% due to the CHIK chronic phase.

Conclusion: Patients may have chronic symptoms up to 5 years after the infection. The total loss of healthy years was approximately 55,000 DALYs. The necessity to provide long-term health care for CHIK infected patients and the heavy global burden of CHIK in Reunion Island underline the importance to target prevention to be more cost-effective.