Source of South African outbreak remains unknown

Almost 50 people fell ill in South Africa after eating or working at a restaurant but investigators have been unable to find the source.

In February 2024, the Western Cape Provincial Communicable Disease Control Coordinator was notified by the National Institute for Communicable Diseases (NICD) of a potential foodborne outbreak linked to a restaurant. 

According to a study in the Public Health Bulletin of South Africa, two initial patients reported that they were from a party of five and all of them had consumed prawns during dinner at a restaurant in Cape Town.

The implicated restaurant is part of a national franchise specializing in local cuisine, including meat, seafood, and poultry. The outlet has seating capacity for 150 guests and employs more than 50 staff, with an average of 15 on duty per shift.

Search for source
A total of 85 individuals were contacted: 51 restaurant staff members and 34 patrons. Among these, 46 were symptomatic: 12 staff and all 34 patrons. Case investigation forms were completed for 28 individuals. The median age of symptomatic cases was 35, with most aged 30 to 39. Fifteen customers were hospitalized but no deaths were reported.

Clinical specimens, stool or rectal swabs, were collected from 49 people, and 33 tested positive for Shigella/Enteroinvasive E. coli (EIEC). Six were clients and 27 were staff. Available molecular tests were unable to distinguish between Shigella and EIEC. Eleven staff were symptomatic. Two specimens tested positive for STEC.

An inspection of the restaurant did not identify any issues regarding food preparation or hygiene practices. However, it found overstocking of cold storage and non-compliance with the first-in, first-out recommendation.

Three food samples — grilled chicken, prawn rissoles and mayonnaise sauce — had coagulase positive staphylococci higher than acceptable limits, and the mayonnaise tested positive for Bacillus cereus. No definite source could be identified. The outbreak ended after the restaurant was closed for cleaning, retraining of staff, and isolation of ill employees.

Ill staff kept working
One staff member experienced symptoms including diarrhea, nausea and vomiting, extreme body aches, and weakness. He then improved but became ill again with the same symptoms on Feb. 7, 2024. He was at work during this time. Eight other staff members were symptomatic but continued to work.

History of food items eaten at the restaurant was available for 24 suspected cases: four staff and 20 patrons. Eighteen reported consuming seafood and 10 had chicken.

Researchers said the incident highlighted several of the common obstacles encountered during foodborne outbreak investigations.

“I hope this study continues the conversation about the risk and importance of foodborne diseases and how they can be prevented. We urgently need national Shigella guidelines to guide outbreak responses. It is also crucial for individuals with foodborne illness to seek healthcare for proper diagnosis and treatment, including specimen collection,” said Janine Bezuidenhoudt, lead study investigator.

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