What contributed to the measles outbreak in Mpumalanga?
Measles is a highly infectious and potentially fatal acute viral disease that predominantly affects young children. It is characterised by fever and a maculopapular rash that typically appears 3–5 days after the onset of respiratory-like symptoms. Complications include diarrhoea, pneumonia, encephalitis, and death. Measles is vaccine-preventable.
Despite the availability of a safe and highly effective vaccine, measles remains a major public health threat. Globally, an estimated 9.2 million cases of measles and 136 000 deaths were reported in 2022. Due to the high number of unvaccinated and under-vaccinated children, the WHO African region has the highest incidence of measles, estimated at 51.5 per million population in 2022. Approximately, 8.7 million children in Africa did not receive a single dose of the measles vaccine in 2021, leaving them vulnerable to infection.
In September 2022, a measles outbreak was declared in South Africa, affecting five of the nine provinces. In Mpumalanga, the outbreak was confirmed on 11 November 2022. Investigations were conducted to identify contributing factors, assess the outbreak’s magnitude, and inform public health interventions aimed at controlling and preventing further spread.
The following report focuses on Mpumalanga, where laboratory-confirmed measles cases were reported between 01 November 2022 and 31 December 2023.
Materials and Methods
The measles surveillance database, containing measles and rubella results and maintained by the Centre for Vaccines and Immunology (CVI) at the NICD, was used as the primary data source. Additional information was sourced from completed case investigation forms, which contained data on age, gender, clinical presentation, medical and contact history, travel history, and vaccination status.
Blood samples collected from suspected measles cases were tested at the NICD for measles and rubella Immunoglobulin M (IgM) antibodies using a commercial Enzyme-Linked Immunosorbent Assay (ELISA) according to manufacturer instructions.
Results
A total of 118 laboratory-confirmed measles cases was reported in Mpumalanga from 01 November 2022 to 31 December 2023, with the number of measles outbreak cases peaking during week 49 of 2022 (starting 11 December). Case numbers started to decline in week 12 of 2023 (starting 19 March 2023), with sporadic cases continuing to be reported in all three districts until 31 December 2023.
The Ehlanzeni and Gert Sibande districts reported the majority of cases, with 45% (n=54) and 39% (n=46), respectively. Females (n=64; 54%) accounted for most of the cases, and more than half of the cases were aged ≤9 years (n=77; 65%). The youngest case was four months old and the oldest was 60 years old, with a median age of seven years (IQR: 3–11 years).
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