Issued by the National Institute for Communicable Diseases based on laboratory testing data.
Data was extracted from the NICD Surveillance Data Warehouse (SDW) up to the end of April 2023. Test data after March 2023 is incomplete due to delays in specimen testing and authorisation. It is also important to note that mumps is diagnosed symptomatically and is not a notifiable medical condition. Available data does not allow us to measure the exact number of test positives in our country and anecdotal reports of suspected clustered or localised outbreaks may continue arising.
For this update, data is grouped by person so that repeat PCR, IgM or IgG tests are duplicated. Proportions are calculated as person testing, not by individual test. Frequency and proportion, and median and interquartile range is used to describe categorical and continuous variables respectively. Descriptive statistics and epidemiological curves are presented. The current working definition for laboratory-confirmed mumps is any person with a positive laboratory test result for mumps IgM or PCR positive for mumps.
Outbreak description
From epidemiological week 01 in 2023 (ending 7 January 2023) to week 17 2023 (ending 26 April 2023), 1702 test results were available of which 580 mumps test positives were identified. The number of samples submitted and the percentage of laboratory-confirmed mumps test positives are shown in Figure 1. For the same period mumps test positives have been identified in eight provinces: Eastern Cape (9 (2%)), Free State (40 (7%)), Gauteng (64 (11%)), KwaZulu-Natal (280 (48%)), Limpopo (11 (2%)), Mpumalanga (97 (17%)), North West (57 (10%)) and Western Cape (22 (4%)) (Table 1). The largest number of mumps test positives are amongst the 5-9 year age group (335 (58%)), followed by the 1-4 year age group (158 (27%)). The epidemic curve continues to illustrate the increase in mumps test positive numbers from week 6, peaking at week 11 (Figure 2). However, the decline in mumps test positives in subsequent weeks may be an artefact of specimen-taking practices and, testing data after March 2023 being incomplete due to delays in specimen testing and authorisation.
Figure 1: Percent-positivity for mumps illustrated from national public sector laboratory data from the NICD surveillance data warehouse for the epidemiological week 01 in 2023 (ending 7 January 2023) to week 17 2023 (ending 26 April 2023).
Table 1: Descriptive statistics for mumps test positives from national public sector laboratory data from the NICD surveillance data warehouse for the epidemiological week 01 in 2023 (ending 7 January 2023) to week 17 2023 (ending 26 April 2023).
Figure 2: Epidemic curve for mumps test positives illustrated from national public sector laboratory data from the NICD surveillance data warehouse for the epidemiological week 01 in 2023 (ending 7 January 2023) to week 17 2023 (ending 26 April 2023).
For more information on mumps, click here
