Diphtheria cases rise to 47 as a Tshwane household cluster adds three

South Africa has 47 laboratory-confirmed cases of respiratory diphtheria this year, up from 44, after a household cluster was found in Tshwane. The National Institute for Communicable Diseases (NICD) set the figures out in its week 44 situational report, dated 6 November, using data drawn on 5 November.

The report covers 29 December 2025 to 1 November 2026. Since the previous report it adds three confirmed cases and one person carrying the bacteria without symptoms, all in Gauteng. The NICD lists them as one household in Tshwane. The infections were recorded in the weeks starting 19 and 26 October.

The count had stood at 44 since the week 42 report on 23 October. The week 43 report added no new cases. The NICD says the figures are provisional and may change as records are cleaned. Cases are counted by the date the first specimen was collected, or by the date the person first became ill if that date is missing.

A household in Tshwane

This is the eighth diphtheria cluster the NICD has recorded in 2026, and the first in Gauteng. Eight clusters this year have involved 32 people. Inside them are 16 confirmed respiratory cases (nine in the Western Cape, four in Limpopo and three in Gauteng), 11 people carrying the bacteria without symptoms, and five probable cases, all of them in Limpopo.

The other seven clusters were earlier in the year. Six were in Cape Town. Five of those were households. One, in May, was in a correctional facility: one respiratory case and three people carrying the bacteria without symptoms. The remaining cluster was a household in Tzaneen, Limpopo, from late May to late June. That household also accounts for all five probable cases in the country.

Outside the clusters, 31 confirmed cases had no known link to another case: 27 in the Western Cape, three in Gauteng and one in Limpopo. The NICD says a public-health response was started for every suspected and confirmed case.

Where the cases sit

The Western Cape still carries most of the outbreak, with 36 of the 47 confirmed respiratory cases (77%). Gauteng now has six (13%) and Limpopo five (11%).

Contact tracing has found 11 people carrying toxin-producing diphtheria bacteria without symptoms: eight in the Western Cape, two in Limpopo and one in Gauteng. Carriers matter because they can pass the infection on without feeling ill.

A further 128 people were reported as suspected cases and then tested negative. Most of those tests were in the Western Cape (95). Gauteng accounted for 11, Limpopo eight, KwaZulu-Natal six, the Free State four, Mpumalanga three and the Eastern Cape one. Some of the people who tested negative were found to have other infections, including streptococcal or staphylococcal illness, or respiratory viruses such as influenza.

The report also counts two cases of toxigenic diphtheria of the skin, both in Gauteng. The first was in week four and the latest in week 33. Skin infection is counted separately from the 47 respiratory cases.

Separately again, the NICD has recorded 32 people with non-toxigenic Corynebacterium diphtheriae. These strains do not produce the toxin that makes respiratory diphtheria dangerous. Fourteen of those 32 people had no symptoms, 17 had skin infection, and one had the bacteria in the blood. They are not part of the 47.

Who has been hit, and who has died

Nine people with confirmed or probable respiratory diphtheria have died this year: six in the Western Cape, two in Limpopo and one in Gauteng. That is a case-fatality ratio of 17% (9 of 52 confirmed and probable cases). Among confirmed cases alone the ratio is 16% (7 of 47). Among the five probable cases it is 40% (2 of 5).

The deaths are not all in one age group. One was among children under 10. Four were among people aged 10 to 19, and four among those aged 30 to 39. No deaths were recorded from 20 to 29, or from 40 upwards. The highest ratio in the table is among people aged 30 to 39, at 36% (4 of 11). The NICD says these age-specific rates rest on small numbers and should be read with caution.

This is not mainly a disease of small children. The median age of confirmed cases is 23, ranging from 4 to 72, and 64% (30 of 47) are adults aged 18 or older. In the age table, 10 confirmed cases are under 10, nine are aged 10 to 19, 14 are aged 20 to 29, 11 are aged 30 to 39, two are aged 40 to 49, and one is 60 or older. None of the confirmed cases fall between 50 and 59. That matters because protection from childhood vaccination wanes without boosters.

What the laboratory shows

Of 60 toxigenic infections identified this year (the 47 respiratory cases, the 11 carriers and the two skin cases), 41 were grown in culture. Four of those cultures could not be kept alive for further testing, leaving 37 isolates. The NICD compared toxin tests on 33 of them. A laboratory method called the Elek test agreed in every case with the genetic test for the toxin gene. No isolate was found that carries the toxin gene but does not produce the toxin.

Antibiotic testing on those 33 isolates, using the EUCAST disc-diffusion method, found all of them susceptible to penicillin, at increased exposure, and to erythromycin. Those are the antibiotics used to treat cases and to protect close contacts.

Genetic sequencing is available for 29 of the 37 viable isolates. Eight results are still pending. Every Western Cape isolate sequenced so far (26) belongs to a single lineage, sequence type 906, first detected in 2023 and so far apparently confined to that province. Two Limpopo isolates belong to ST824, a type also found in Limpopo and Mpumalanga cases in 2025. One skin-infection isolate is ST447, a type previously seen in another Gauteng skin case in 2025. The report does not yet say whether the Tshwane respiratory cases belong to the Western Cape lineage.

What to watch for

Respiratory diphtheria is caused by strains of Corynebacterium diphtheriae that produce a toxin. It spreads through respiratory droplets and close contact. Warning signs include a sore throat, fever, swollen neck glands and a grey or white membrane at the back of the throat. The toxin can damage the heart and nerves, so anyone with these symptoms should see a clinician quickly rather than wait it out.

Diphtheria is preventable by vaccination. Diphtheria-containing vaccines are part of South Africa's routine childhood schedule, with booster doses during childhood. Parents can check a child's Road to Health booklet. Adults who are unsure of their own vaccination history can ask at a clinic.

None of this replaces advice from your own clinician. If you are unsure about symptoms, a close contact, or whether you or a child needs a booster, contact a pharmacy, clinic or your doctor.