South Africa is facing a sustained outbreak of diphtheria, a vaccine-preventable disease that has re-emerged with alarming force and the Western Cape has emerged as the epicentre, carrying a disproportionate share of cases, clusters and deaths compared to the rest of the country.

This is according to the latest situational report by the National Institute for Communicable Diseases (NICD), 91 laboratory-confirmed cases of toxigenic respiratory diphtheria have been recorded nationally between January 2024 and 18 January 2026.

Of these, 67 cases, nearly three quarters were reported in the Western Cape, vastly exceeding numbers seen in other provinces such as Limpopo (9), Mpumalanga (8), Gauteng (4) and KwaZulu-Natal (3).

The NICD notes that “the majority of confirmed cases and carriers (76%) are from the Western Cape,” underscoring the province’s central role in the outbreak.

Patterns of transmission further illustrate the severity of the situation in the province. Since late 2024, 25 diphtheria clusters have been identified across South Africa, 15 of them in the Western Cape, mainly in Cape Town. These clusters have occurred repeatedly in households, communities and correctional facilities, indicating persistent transmission rather than isolated flare-ups. In contrast, Limpopo has recorded five clusters, Gauteng two, and KwaZulu-Natal and Mpumalanga one each.

Beyond identifiable clusters, the Western Cape has also reported a high number of sporadic cases with no known epidemiological link. Of the 49 sporadic respiratory cases recorded nationally, 39 occurred in the Western Cape, suggesting undetected chains of transmission in the broader community. Other provinces recorded only a handful of sporadic cases.

The NICD describes diphtheria as “a highly contagious vaccine-preventable illness which can lead to severe complications, including myocarditis and nerve damage, and can be fatal if treatment is delayed”.

A total of 19 deaths have been recorded among probable and confirmed respiratory diphtheria cases nationwide, resulting in an overall case-fatality ratio of 21%. Twelve of these deaths occurred in the Western Cape.

Vaccination gaps appear to be a key driver of vulnerability. Among children aged 12 years and younger who fell ill, several were unvaccinated or had not received booster doses, while others had only completed part of the infant immunisation schedule. The report stresses that protection depends not only on early childhood vaccination but also on booster doses later in life.

“Individuals of all ages can seek assistance at public health care clinics to review their vaccine status and receive booster dose/s as indicated,” the NICD advises.

In response to the outbreak, public health authorities have implemented contact tracing, isolation of contacts, antibiotic prophylaxis and vaccination of exposed individuals across affected provinces.

The NICD confirms that “appropriate public health responses have been initiated for all suspected and confirmed cases”, with additional vaccination campaigns conducted in schools and communities, particularly in the Western Cape and Limpopo. However, the continued detection of new clusters and sporadic cases suggests that transmission has not yet been fully contained.

The NICD notes that all sequenced Western Cape isolates belong to a single strain, indicating sustained local transmission rather than repeated importation from elsewhere.

This article is based on the latest situational report released by the National Institute for Communicable Diseases.

The situation remains fluid, and this is a developing story.

At the time of publication, the Western Cape Department of Health had not yet responded to questions regarding additional actions or long-term plans to mitigate the outbreak.

lilita.gcwabe@inl.co.za

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