Descriptive analysis of measles cases during an outbreak in Northeastern Uganda

Abstract

Introduction: In Uganda, measles outbreaks persist due to challenges in public health infrastructure, low vaccination coverage, and socio-economic factors. Moroto District reported a measles outbreak in April 2024 affecting all eight sub-counties. We investigated from April to July 2024 to describe the outbreak and identify predisposing factors in the three most affected sub-counties.

Methods: We reviewed medical records from April to July 2024 in three health facilities in the most affected sub-counties and conducted six key informant interviews with district health officials. A suspected measles case was defined as any person with fever and maculopapular rash plus cough, coryza, or conjunctivitis; a confirmed case in this outbreak was a suspected case with laboratory-confirmed measles IgM or a clinically confirmed case. After confirmation of five cases, subsequent suspected cases were considered measles-positive through epidemiological linkage. Data were analysed in Microsoft Excel to obtain descriptive statistics. Attack rates were computed using the projected sub-county populations from the Uganda Bureau of Statistics, and inductive thematic analysis was used to analyse the qualitative data.

Results: A total of 180 measles cases were reported across the three sub-counties, with no deaths. The majority were females (53%, 95/180), with a median age of 2 years (Interquartile range: 1-3years), and 81.7% (147/180) of cases were children under 4 years. Lotisan Sub-County recorded the highest attack rate (33 cases per 1,000), followed by Rupa (16 cases per 1,000) and Nadunget Town Council (6 cases per 1,000). Peak admissions occurred in July (36 cases). Key informant interviews identified low vaccination coverage, poor housing, and cross-border movement from Turkana County, Kenya, which had an ongoing measles outbreak, as the possible predisposing factors.

Conclusion: The Moroto measles outbreak predominantly affected children under five years, highlighting their vulnerability. The July spike corresponded with the influx of pastoralists from Turkana, Kenya, a measles high-risk area. Strengthening vaccination coverage, border surveillance, and community risk communication is vital for controlling and preventing future outbreaks in pastoralist communities.