Listeria monocytogenes. Picture: Centres for Disease Control and Prevention

Geneva - The outbreak of listeriosis that South Africa is experiencing is the largest outbreak of listeriosis ever reported worldwide, the World Health Organisation (WHO) says. 

The outbreak was declared on December 5 last year, and out of 134 traced patients, 61 have died, the WHO said Friday.

“Listeriosis is a real challenge to health services because it involves so many sectors – not only health services, but the food industry as well as agriculture and farming,” WHO media officer Christian Lindmeier told journalists at a UN briefing.

“Listeria infection leads to unplanned abortions in pregnant women or death of newborn babies.”

The WHO said the disease occurrence is relatively low and an investigation into the source of the outbreak is ongoing.  

However, listeria’s severe and sometimes fatal health consequences, particularly among infants, children and the elderly, count it among the most serious of foodborne infections.

Lindmeier said nearly two-thirds of the cases have been reported from Gauteng.

Read more: Health department races against time to find source of #Listeriosis

“Listeria is found in unpasteurised dairy products and various ready-to-eat foods and can grow at refrigeration temperatures,” he said.

WHO noted that the people who are becoming infected are from a diverse socio-economic background with both private and public hospitals reporting cases. 

At particular risk are neonates (40 percent), mostly becoming infected from their mothers.

Immuno-compromised people, such as people living with HIV and cancer are also at higher risk, said WHO.

“South Africa has implemented some very important measures such as making listeriosis a notifiable disease for the first time ever,” said Lindmeier. 

“This means that when a clinic gets a case of listeriosis, they must notify the government. This is helping to track the disease.”

 A complication in fighting the disease is that it takes about three weeks between when a person eats or drinks contaminated food or drinks and when they actually become sick.

Also read: Newborn babies are the worst affected by #Listeriosis outbreak

Due to this long incubation period, it’s hard to identify the food source, said WHO. 

“Even if a food source is identified, we can expect to have cases reported for several weeks to come,” said Lindmeier. “This is making the investigation into the source of the outbreak particularly complex.”

Some people are at particular risk of a severe outcome – pregnant women and people with weakened immune systems. 

For example, pregnant women are 20 times more likely to get listeriosis than other healthy adults. This puts their health and the health of their baby at risk.

The WHO recommends that if you are pregnant or living with HIV or cancer, that you avoid high risk food.

This includes luncheon or deli meats like ham and sausages, meat spreads, smoked fish, and soft cheese made from unpasteurised milk.

It says meat and chicken should be thoroughly cooked.

“When you are pregnant or have weakened immune systems it is always a good idea to be careful with what you eat. With the listeriosis outbreak you should be extra vigilant,” said Lindmeier.

Independent Foreign Service