Prevalence and clinical and evolutionary epidemiological profile of chikungunya cases during the first epidemic in Chad in 2020

The emergence and re-emergence of infectious agents is a real threat to public health. In recent years, we have noticed a re-emergence of arboviruses, including chikungunya. In July 2020, Chad experienced its first confirmed outbreak of chikungunya in the Ouaddaï province, more precisely in the Abèche health district. The aim of this study is to determine the prevalence of chikungunya cases in the specified district and to describe their clinical characteristics and epidemiological progression. This cross-sectional study used an operational definition to identify chikungunya cases. Cluster sampling was employed to select participants. Relative frequencies related to sociodemographic characteristics, clinical data, knowledge, attitudes, and practices were calculated. In addition, the prevalence was estimated with its 95% confidence intervals (CI). The prevalence of chikungunya disease among people meeting the case definition was estimated at 78%. The most affected age group was 5-14 years (30%), followed by 15-24 years (27%). Females accounted for the majority of cases (54%). Clinically, fever and disabling arthralgia were found in 100% of respondents. Headaches were present in 87% of respondents. Gastrointestinal signs were dominated by vomiting (44%), and the most frequently reported cutaneous signs were rashes (22%) and pruritus (17%). A significant number of respondents had sought help from a traditional healer (26%). Of the 1,902 chikungunya cases, 1,781 (93%) reported persistent pain lasting more than 3 weeks, but of varying intensity. Chikungunya has a very low case-fatality rate, but a non-negligible impact on the health of the population. In our study, the high prevalence in the Abéché district testifies to the extent of the disease during the first epidemic. Better epidemiological surveillance, coupled with effective vector control, could prevent future epidemics in other towns in the country.