Measles outbreak in Semuto Subcounty, Nakaseke District, Uganda, June–August 2021
Edirisa Juniour Nsubuga, Job Morukileng, Josephine Namayanja, Daniel Kadobera, Fred Nsubuga, Irene B. Kyamwine, Lilian Bulage, Benon Kwesiga, Alex Riolexus Ario, Julie R. Harris
Abstract
Semuto Subcounty reported rubella/measles outbreaks in January 2020 and June–August 2021. This study investigated the outbreak in 2021 to determine the scope, and the factors associated with transmission. A probable case was defined as a resident of Semuto Subcounty with acute onset of fever and a generalized maculopapular rash with either cough/cold or red eyes from 1 June to 31 August 2021. A confirmed case was defined as a probable case with a blood sample positive for measles-specific IgM. A village-matched case–control study was conducted with 30 cases and 122 controls (1:4 ratio). A control was defined as an individual aged 6 months–9 years, sampled at random, with no signs or symptoms of measles from 1 June to 31 August 2021, residing in the same village as the matched case. Adjusted Mantel–Haenszel odds ratios (ORMH) and confidence intervals (CIs) were calculated. Of the 30 cases (27 probable and three confirmed), 16 (53%) were male. The subcounty attack rate (AR) was 3.2/1000. Children aged 5–9 years were the most affected (AR 5.0/1000). Twenty-two (79%) cases and 116 (97%) controls had ever received measles vaccine (ORMH 0.13, 95% CI 0.03–0.52). Interaction with symptomatic persons at water collection points (ORMH 4.4, 95% CI 1.6–12) and playing at community playgrounds (ORMH 4.2, 95% CI 1.7–11) increased the odds of infection. Socializing/congregating at water collection points and community playgrounds facilitated the transmission of measles in this outbreak.