Descriptive epidemiology of cholera outbreak in Nigeria, January–November, 2018: implications for the global roadmap strategy

The choleraoutbreak in 2018 in Nigeria reaffirms its public health threat to the country. Evidence on the current epidemiology of cholerarequired for the design and implementation of appropriate interventions towards attaining the global roadmap strategic goalsfor choleraelimination however seems lacking. Thus, this study aimed at addressing this gap by describing the epidemiology of the 2018 choleraoutbreak in Nigeria. This was a retrospective analysis of surveillance data collected between January 1st and November 19th, 2018. A choleracase was defined as an individual aged 2 years or older presenting with acute watery diarrhoea and severe dehydration or dying from acute watery diarrhoea. Descriptive analyses were performed and presented with respectto person, time and place using appropriate statistics. There were 43,996 choleracases and 836 choleradeaths across 20 states in Nigeria during the outbreak period, with an attack rate(AR) of 127.43/100,000 population and a case fatality rate(CFR) of 1.90%. Individuals aged 15 years or older (47.76%) were the most affected age group, but the proportion of affected males and females was about the same (49.00 and 51.00% respectively). The outbreak was characterised by four distinct epidemic waves, with higher number of deaths recorded in the third and fourth waves. States from the north-west and north-east regions of the country recorded the highest ARs while those from the north-central recorded the highest CFRs. The severity and wide-geographical distribution of choleracases and deaths during the 2018 outbreak are indicative of an elevated burden, which was more notable in the northern region of the country. Overall, the findings reaffirm the strategic role of a multi-sectoral approach in the design and implementation of public health interventions aimed at preventing and controlling cholerain Nigeria.