Epidemiology of measles in Angola: Results from routine surveillance from 2015 to 2021

Background: Measles, an acute infectious disease of extremely contagious viral aetiology, has been eliminated in some parts of the world. To the best of the authors' knowledge, this is the first study on the epidemiological pattern of the measles virus in Angola, and it was carried out through a review of 7 years of observational retrospective data from the national measles laboratory surveillance programme. Methods: A retrospective study using national databases on the laboratory surveillance of measles was performed. Patients of all ages with suspected measles from all provinces of Angola were included. Serum samples were used to detect IgM-type measles-virus-specific antibodies by enzyme-linked immunosorbent assay. Findings: In total, 3690 suspected measles samples were sent to the Instituto Nacional de Investigacao em Saude. There were 962 (26.1%) laboratory-confirmed cases, and the most affected age group was children aged 1-4 years. The highest incidence rate per 100,000 population was found in Benguela (17.9%), followed by Huambo (16.7%) and Cuanza Sul (13.6%). Of the study years, the incidence rate per 1,000,000 population was highest in 2020 (11.9%). The most common complication was diarrhoea ( n = 406, 42.2%). Of the confirmed cases, 209 (21.7%) were vaccinated, 633 (65.8%) were unvaccinated, and 120 (12.5%) had unknown vaccination status. For all study years, vaccination coverage was < 70%. Interpretation: Measles continues to be a serious problem in Angola, and more efforts are needed to increase measles surveillance and achieve a high percentage of vaccination coverage.