Australian experts urge proper cooking after finding parasites in meat

Scientists in Australia have identified a parasite in wild deer and wild pigs for the first time.

Researchers from Charles Sturt University discovered the parasite Sarcocystis during their work and said it sheds light on a previously unrecognized risk.

A variety of wild game meats, including deer and wild pig, are hunted and consumed in Australia.

Sarcocystis can infect humans in two ways: Intestinal sarcocystosis is usually asymptomatic, although symptoms may include nausea, abdominal pain, and self-limiting diarrhea that usually resolves within 36 hours. Extraintestinal sarcocystosis is usually asymptomatic, with infection of the muscles leading to symptoms such as painful muscle swelling, fever, tender muscles, weakness and difficulty breathing.

The European Food Safety Authority (EFSA) has previously identified Sarcocystis hominis and Sarcocystis suihominis as zoonotic hazards.

Potential health risk
The research team examined the esophageal, diaphragm and heart tissues of 90 deer and eight wild pigs in the southeastern regions of the country, looking for visual signs of Sarcocystis cysts. The findings were published in the International Journal of Food Microbiology.

Although no cysts were detected, polymerase chain reaction (PCR) testing and histopathology confirmed the presence of the parasite.

The research was led by professor of veterinary parasitology Shokoofeh Shamsi, who said the findings are worrying because they suggest infected animals, especially free-range animals, can pass meat quality checks undetected.

“This poses a potential food safety risk if the meat is consumed without thorough cooking, which could lead to human infections. Understanding the extent of Sarcocystis infections in game meat is crucial for food safety and public health,” she said.

The study also highlighted potential implications for the Australian pork industry, with the growing trend towards free-range pig farming. The potential for the infection to spread between wild and domestic pigs in free-range systems underlines the need for continued surveillance and research to determine the prevalence and species of Sarcocystis in wild animals, scientists said.

Risk from other parasites
As part of National Science Week, the Food Safety Information Council warned of the risk of parasites, including toxoplasmosis and cryptosporidiosis infections, from August 10 to 18.

Cryptosporidium can be spread by swimming in contaminated water, by contact with an infected person or animal, or by drinking unpasteurized milk.

Shamsi said research by Food Standards Australia New Zealand (FSANZ) and the Australian National University found there were 15,500 cases of toxoplasmosis in Australia each year. People become infected through cats or by eating raw or rare sheep, pork or game meat.

Another study in Scotland revealed viable Toxoplasma gondii in two venison products.

A previous analysis of retail meat in Scotland found that Toxoplasma gondii was common in venison products, but the risk to public health could not be assessed because the viability of the parasite had not been established.

In the latest work, published in the Food Control magazine23 venison products were purchased from farm shops or supermarkets in 2020. Viable Toxoplasma gondii was isolated from two of the five positive samples.

“This is the first study to report the presence of viable Toxoplasma gondii in retail venison and highlights the potential risk to public health if this meat is eaten undercooked. Consumers should freeze or thoroughly cook venison before consuming to reduce the risk of foodborne toxoplasmosis,” researchers said.

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