Before long, the pork industry will have certification programs underway for two pork parasites, Trichinella spiralis and Toxoplasma gondii.
USDA's Agricultural Research Service (ARS), university scientists and the National Pork Producers Council are involved in cooperative research developing tools to implement and monitor certification systems on the farm.
Trichinella is a nematode worm found in muscle meat. Though incidence has been in decline for decades, its continued, high-profile existence has served to tarnish the image of the pork industry.
Toxoplasma is a single-celled protozoan parasite found in muscle and organ tissue. Its existence has only been documented in recent years. The role of pork in human toxoplasmosis is unknown.
Good news is that both parasites are disappearing. Modern swine husbandry has made it almost impossible to find hogs infected with trichinella. Even those that are detected are at very low levels and pose virtually no risk to public health.
Toxoplasma infection has also declined, but still occurs in 2% or more of market hogs and at higher rates in breeding stock.
In cleaning up the two parasites, producers must maintain stringent management programs coupled with testing.
Pigs can only become infected with trichinella by eating infected muscle tissue. Rats and wildlife are the most common sources of trichinella. Prevention consists of rodent control programs and barriers to wildlife.
Control of toxoplasma is a bit tougher. Pigs can become infected by eating infected tissues such as rodents and small mammals. But in addition, cats pass a resistant stage of toxoplasma (the oocyst) which if ingested can infect the pig. So while prevention includes rodent control, it largely depends on isolation of cat populations from pigs, feed and feed storage areas.
The trichinella control program is well underway. A farm audit has been developed which documents good production practices that limit the risk of infection. The audit could lead to producers selling their product as "trichinae certified." A similar audit is proposed for toxoplasma.
To support certification, it will be necessary to verify freedom from infection. ARS scientists have developed a simple blood test for both parasites which takes just minutes to perform using samples collected at slaughter. These same tests can be run using fluids collected from small meat samples.
Researcher: R. Gamble, Parasite Biology and Epidemiological Laboratory, Agricultural Research Service, Beltsville, MD. Phone ARS at (301) 504-8431.