‘Strong lead’ in South African Listeria outbreak - WHO

By Joseph James Whitworth contact

- Last updated on GMT

Picture: iStock
Picture: iStock

Related tags: South africa, Epidemiology

The lack of knowledge on the source of the Listeria outbreak in South Africa is ‘of concern’ but a ‘strong lead’ is being investigated, according to the World Health Organization (WHO).

The National Institute for Communicable Diseases (NICD) said 852 laboratory confirmed cases have been reported since January 2017 with 107 deaths.

WHO has sent a food safety expert, an epidemiologist with expertise in listeriosis outbreak investigation and a risk communication specialist to the country.

The organization said there was inadequate funding for lab testing given the large number of samples and insufficient capacity for data analysis to identify links between cases.

The outbreak is of concern because of its national scale and lack of identification of the source.

“Case investigation activities and testing of food and environmental samples need to be accelerated to facilitate the identification of the source of contamination and implementation of response measures to bring the outbreak to an end,”​ said WHO.

Pending lab results on possible source

Technical support has been provided for surveillance and collection of case investigation data to identify the link between cases.

A case investigation is ongoing and is focusing on linking cases and any food or environmental samples that test positive for Listeria monocytogenes.

Genetic testing on Listeria from patients suggests sequence type 6 (ST6) is responsible for most infections.

WHO said an investigation team is working on what is considered a ‘strong lead’ between human cases and a food item with laboratory results pending.

“Challenges include a long period before laboratory results are available, inadequate funding for laboratory testing given the large number of samples, infrequent and insufficiently detailed updates regarding the outbreak, and lack of finalization of risk communication materials. There is also insufficient capacity for data analysis to identify links between cases," ​it said.

“Identification of additional funding for laboratory testing and increased collaboration with laboratories in-country will be needed to increase the pace of testing of food and environmental samples in South Africa.

“Linkage of the results of these samples with case investigation data is urgently needed to enable identification of the source of contamination and rapid implementation of measures to control the outbreak.”

Update case statistics

South Africa has made listeriosis a notifiable disease meaning every diagnosed patient must be reported.

Most cases have been reported from Gauteng Province (59%, 505/852), followed by Western Cape (107) and KwaZulu-Natal (63).

Where age was reported (823), it ranged from birth to 93 (median 19 years) and 42% are neonates aged 28 days or younger.

Females accounted for 55% of cases for whom gender was reported.

Final outcome data are available for 42% of cases of which 30% (107/355) have died.

NICD said Environmental Health Practitioners in all provinces are systematically inspecting and sampling diverse food production, processing and packaging facilities.

Cases of listeriosis will continue to be investigated with traceback and further investigation of any positive food/environmental samples.

The European Centre for Disease Prevention and Control (ECDC) said based on WGS analysis no associated cases were reported in EU/EEA and the risk of spread to Europe is very low.

Related topics: Food Safety

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