Investigations of a diphtheria outbreak in Mpumalanga province, South Africa, 2025
1
Division of Public Health Surveillance and Response (DPHSR), National Institute for Communicable Diseases (NICD), Johannesburg, South Africa
2
Communicable Disease Control (CDC), Mpumalanga Department of Health, Mbombela, South Africa
3
Maternal Child and Women's Health, Mpumalanga Department of Health, Mbombela, South Africa
Popul. Med. 2026;8(Supplement Supplement 1):A3934
ABSTRACT
INTRODUCTION:
Diphtheria is a life-threatening and vaccine-preventable upper respiratory tract infection commonly caused by toxigenic strains of Corynebacterium diphtheriae. Failure to immunise during childhood increases the risk of outbreaks. Between February and May 2025, an outbreak of diphtheria occurred in Mpumalanga Province, South Africa. Investigations were conducted to describe the extent of the outbreak and to implement control measures.
METHODS:
Case investigations involved management of close contacts and laboratory testing of collected throat swabs. A descriptive analysis was conducted for all laboratory-confirmed cases. Health promotion activities were held in the community, case management trainings were conducted for clinicians, and a vaccination catch-up campaign aimed at all fifth-grade learners (≥ 9 years) was conducted across all districts.
RESULTS:
Eleven laboratory-confirmed cases of diphtheria were reported between February and May 2025, with ages ranging from 4 to 55 years (median=26; IQR: 13-32). Ehlanzeni (n=7; 64%) and Nkangala (n=4; 36%) districts accounted for all laboratory-confirmed cases, while suspected cases were reported from all districts. The majority of cases (n=8; 73%) were symptomatic and hospitalised, while 27% were asymptomatic carriers. All cases were treated with azithromycin 500 mg, and only 5 (63%) of the symptomatic cases received the diphtheria anti-toxin (DAT). Three deaths were reported (case fatality rate =27%). The outbreak primarily affected adults (72%), and all had an unknown vaccination status. Of the three children, one missed the diphtheria vaccine dose at 6 years and 12 years. Over 260 close contacts were traced and managed, including 168 Healthcare workers. The catch-up campaign resulted in 87% immunisation coverage.
CONCLUSIONS:
The outbreak of diphtheria highlighted existing immunity gaps in the province. To prevent future outbreaks, the diphtheria vaccination coverage needs to be improved, and the potential of providing booster doses in adulthood needs to be explored.
Diphtheria is a life-threatening and vaccine-preventable upper respiratory tract infection commonly caused by toxigenic strains of Corynebacterium diphtheriae. Failure to immunise during childhood increases the risk of outbreaks. Between February and May 2025, an outbreak of diphtheria occurred in Mpumalanga Province, South Africa. Investigations were conducted to describe the extent of the outbreak and to implement control measures.
METHODS:
Case investigations involved management of close contacts and laboratory testing of collected throat swabs. A descriptive analysis was conducted for all laboratory-confirmed cases. Health promotion activities were held in the community, case management trainings were conducted for clinicians, and a vaccination catch-up campaign aimed at all fifth-grade learners (≥ 9 years) was conducted across all districts.
RESULTS:
Eleven laboratory-confirmed cases of diphtheria were reported between February and May 2025, with ages ranging from 4 to 55 years (median=26; IQR: 13-32). Ehlanzeni (n=7; 64%) and Nkangala (n=4; 36%) districts accounted for all laboratory-confirmed cases, while suspected cases were reported from all districts. The majority of cases (n=8; 73%) were symptomatic and hospitalised, while 27% were asymptomatic carriers. All cases were treated with azithromycin 500 mg, and only 5 (63%) of the symptomatic cases received the diphtheria anti-toxin (DAT). Three deaths were reported (case fatality rate =27%). The outbreak primarily affected adults (72%), and all had an unknown vaccination status. Of the three children, one missed the diphtheria vaccine dose at 6 years and 12 years. Over 260 close contacts were traced and managed, including 168 Healthcare workers. The catch-up campaign resulted in 87% immunisation coverage.
CONCLUSIONS:
The outbreak of diphtheria highlighted existing immunity gaps in the province. To prevent future outbreaks, the diphtheria vaccination coverage needs to be improved, and the potential of providing booster doses in adulthood needs to be explored.
| eISSN: | 2654-1459 |
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