Confirmation Of Mumps Outbreak, South Africa, 2023

 

Mumps is an acute viral infection caused by the rubulavirus, also known as mumps virus. It is sometimes called ‘infectious parotitis’, as it causes painful swelling of the parotid and or salivary glands. Mumps is generally a mild childhood disease, mostly affecting children between 5-9 years of age. However, younger and older children as well as adults, can become infected with mumps. People who have had mumps are usually protected for life against another mumps infection. However, second occurrences of mumps do rarely occur.

Outbreak Description

From epidemiological week 01 in 2013 (ending 05/01/2013) to week 12 2023 (ending 31/03/2023), 1322 mumps IgM positives and 30 mumps PCR positives (11 (37%) in 2023) were identified from 20813 combined tests. Annual percent-positivity for mumps IgM had previously peaked at 39% in 2019, however, the percent-positivity for 2023, from available data, is 69%. Annual percent-positivity for mumps IgM tests by age category shows marked increases in percent-positivity in the 1-4-year age category (84% in 2023) and the 5-9-year age category (83% in 2023), followed by the 30-34-year age category (67%) and 10-14-year age category (54%).

More recent data presented as an epidemic curve, shows unexpected, steady increases in IgM test positives from week 6 of 2023 with KwaZulu-Natal, Mpumalanga and Gauteng accounting for the majority. The unexpected, sudden increase in mumps IgM and PCR test positives, in the absence of other data, constitutes an outbreak.

 

Sinenhlanhla Jimoh

Senior Communications Manager

National Institute for Communicable Diseases