Scientists report first case of rare parasite in pigs, posing human health risks

A recent study has revealed the presence of a rare parasite called Sarcocystis miescheriana in a domestic pig in central Poland.

The finding has captured attention because it involved cysts large enough to be spotted during routine meat inspection at a slaughterhouse. Such occurrences are seldom recorded, which makes this detection especially noteworthy.

Rarely seen, but concerning

Experts point out that large, visible cystic lesions associated with Sarcocystis miescheriana do not show up in pigs very often.

The research describing this event appears in the Journal of Veterinary Research and has underscored how crucial it is to catch uncommon cases during meat inspections. 

In general, most pigs do not exhibit any obvious weight loss or breathing problems when infected. This subtle presentation can make early identification challenging in typical farming setups.

A dedicated research team led by Dr. Weronika Korpysa-Dzirba from the Department of Parasitology and Invasive Diseases at the National Veterinary Research Institute (NVRI) utilized molecular methods, such as analyzing specific genes, to confirm that these rice-grain-sized nodules were indeed S. miescheriana. 

They extracted ten lesions – each about 0.39 inches long by 0.12 inches wide (1 cm x 0.3 cm) and verified them through gene sequencing.

Testing confirmed the parasite’s presence, marking the first time scientists have used molecular tools in Poland to verify the presence of S. miescheriana in a pig.

Impact on farmers and slaughterhouses

Carcass condemnation is possible when these lesions appear, since they raise safety flags during post-mortem inspection. Economic hits can follow if part or all of a carcass gets rejected. 

Beyond financial losses, the presence of parasites calls for more frequent monitoring and better farm management.

Ongoing tests could help producers avoid surprises at the slaughterhouse, which in turn safeguards public confidence in pork products.

What is this pig parasite?

“Sarcocystis infections are quite prevalent in farm animals (higher than 70% in some herbivore populations); however, there have been few outbreaks of clinical disease. Most animals are asymptomatic, and the tissue cysts (chronic stage) are [typically] discovered only at slaughter,” stated the Merck Veterinary Manual.

This reference also notes that severe infections can lead to condemned meat if cysts are visible. Even though subclinical infections may not affect an animal’s day-to-day appearance, the discovery of noticeable cysts can trigger concern among inspectors and consumers.

Why human awareness matters

“In the intestinal type, people get infected by eating undercooked meat containing the parasite. In the muscular type, eating food or water contaminated with the parasite is a risk factor,” warns the CDC.

“An animal will defecate a form of the parasite out, which can then contaminate food or water that people may drink.”

Although S. miescheriana itself is not considered transmissible to humans, other varieties, such as S. hominis and S. suihominis, do pose a risk.

Vigilance in the meat supply chain can help cut down on the chance that people get infected, and proper cooking and handling of the meat is essential to keep the parasites at bay.

Investigating the bigger picture

Researchers have suggested that future studies should determine how often S. miescheriana appears in both domestic and wild pigs. At the moment, data on the frequency and distribution of infections remains patchy. 

Molecular testing could become a standard part of swine meat inspection if scientists confirm significant risks. This would help pinpoint infected herds more swiftly, reduce the spread of infection, and catch other parasitic species that are more dangerous to people.

How to reduce pig parasite risk

Pork producers can lower the odds of Sarcocystis contamination by improving on-farm hygiene. Measures like stopping dogs or wild canids from roaming near pig pens may help because the parasite can cycle among animals through fecal contamination. 

Adequate disinfection methods in barns and strict feed control can also cut down infection rates. Another level of defense is making sure pork is cooked thoroughly, which inactivates parasites that might lurk in undercooked meat.

Experts plan to broaden their use of modern lab techniques at slaughterhouses. They hope this will catch parasitic infections before they enter the market.

Regulatory bodies could use these methods, along with conventional inspections, to give consumers safer products and maintain trust in the pork sector. 

Some producers might see higher costs if advanced testing becomes routine, yet these steps could help avoid the larger price tag of losing entire carcasses due to suspicious lesions.

The full research report will be published in the Journal of Veterinary Research.

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