The National Institute for Communicable Diseases (NICD) says it has recorded an unexpected, sudden increase in mumps, which constitutes an outbreak.
According to the public health institute, mumps is an acute viral infection caused by the rubulavirus, also known as the mumps virus.
"It is sometimes called 'infectious parotitis', as it causes painful swelling of the parotid and or salivary glands."
Mumps, the NICD said, is generally a mild childhood disease, mostly affecting children between the ages of five and nine.
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."
According to the NICD, the annual percent-positivity for mumps immunoglobulin M (IgM) peaked at 39% in 2019 and reached 69% in 2023.
IgM antibodies are the first immunoglobulins also known as antibodies the body makes after being exposed to germs.
According to the World Health Organisation (WHO) vaccine-preventable diseases monitoring system's 2019 global summary, only two Southern African countries - eSwatini and Zambia - frequently reported cases of the mumps between 1999 and 2018, whereas South Africa only reported 24 cases in 2002.
"Mumps reporting has been inconsistent and limited reports on mumps epidemiology in South Africa. Mumps is not a notifiable medical condition and is not included in any formal surveillance programme."
However, since February 2023, the NICD said it has received many enqueries related to possible clusters or outbreaks of mumps in different provinces.
"To confirm the existence of an outbreak of mumps, national public sector laboratory test data for mumps PCR [polymerase chain reaction] positives and IgM positives over the period 2013 to current, was requested from the NICD surveillance data warehouse and analysed as an ad hoc surveillance activity."
Annual percent-positivity for mumps IgM tests by age category in 2023 shows marked increases in percent-positivity in the one to four-year age category (84%) and the five to nine-year age category (83%), followed by the 30 to 34-year age category (67%) and 10 to 14-year age category (54%).
Recent data shows a steady peak in IgM test positives, with KwaZulu-Natal, Mpumalanga and Gauteng accounting for the majority.
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To limit transmission during an outbreak, the NICD said, public health authorities might recommend an additional dose of the combination measles, mumps and rubella (MMR) vaccine for people who belong to groups at increased risk for getting mumps.
"These groups are usually those who are likely to have close contact, such as sharing sports equipment or drinks, kissing, or living together, with a person who has mumps. As the MMR vaccine as an intervention is not universally available in South Africa, it is best to seek the advice of your local healthcare provider."
