South Africa’s National Listeria Incident Management Team issued another of its periodic reports recently for the world’s largest listeriosis outbreak. It says there were no new cases of listeriosis during the week before publication on July 26.
Between Jan. 1, 2017, and July 17, 2018, South Africa recorded 1,060 laboratory-confirmed cases of listeriosis resulting in 216 deaths. It added 87 confirmed cases to the outbreak totals after the March 4 recall of implicated ready-to-eat meat products.
Before 2017, South Africa experienced only 60 to 80 confirmed listeriosis cases each year or about one case per week. Listeriosis reports to the National Institute for Communicable Diseases (NICD) accelerated last year, causing Dr. Aaron Motsoaledi, Minister of Health, to declare the outbreak last December.
The Incident Management Team is conducting inspections of South Africa’s 158 meat processing facilities. It collected environmental swabs for testing from 132 of the 146 meat processing facilities inspected to date. The IMT expected to complete inspections of all 158 meat processing facilities by the end of July, including 14 not currently in production. Where tests are favorable for the presence of Listeria monocytogenes, follow up is being done by districts with support from the National Department of Health and the IMT.
Among the data from NICD’s report are:
The number of new cases reported each week has decreased since the implicated products were recalled on March 4, with no new cases reported during the week prior to release of this situation report. (Figure 1). Neonates, infants 28 days or younger, are the most affected age group, accounting for 42 percent, or 443 of the 1,060 people confirmed with listeriosis. People aged 15 to years old accounted for 32 percent, or 334 of the confirmed cases (Figure 2). Most cases have been reported from Gauteng Province with 58 percent, or 614 of the cases, followed by Western Cape at 13 percent, or 136 cases, and KwaZulu-Natal at 8 percent, or 83 of the cases (Table 1). Final outcomes (i.e. death or discharge) are known for 76 percent, or 806 of the total cases to date; of the known outcomes, 27 percent, or 216, died.
However, it is anticipated that cases could still be reported for the following reasons:
- The incubation period of listeriosis can be up to 70 days.
- The implicated products have a long shelf life and it is possible that despite the recall some products have not been removed from retail locations or consumer’s homes.
- Cross-contamination at retail and in the home can easily occur.
Since March 5, one day after the recall, all new victims with laboratory-confirmed listeriosis are being contacted by IMT members to obtain comprehensive food histories on them. The interviews are designed to determine what food products are possible sources of the exposure Listeria.
Of 87 patients confirmed after the recall, 65 have been interviewed to date.
Of those interviewed, 38/65 (58%) of ill people or their proxy reported consuming polony prior to their illness onset; brands manufactured by Tiger Brands Enterprise Foods were most commonly reported to have been consumed where brand of polony was known.
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