Trichinellosis (Trichinosis) FAQs

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What you need to know:

What is trichinellosis? [Trichinellosis (TRICK-a-NELL-o-sis)/Trichinosis (TRICK-a-NO-sis)]
A person can get trichinellosis (trichinosis) after eating improperly cooked meat infected with the worm Trichinella spiralis. When a person eats meat from an infected animal, trichinella cysts hatch in the intestines and grow into adult roundworms. The roundworms then produce offspring that migrate through the lining of the intestines and into the bloodstream. These parasites invade muscle tissues, including the heart and diaphragm. They can also affect the lungs and brain.

What are the symptoms of trichinellosis? What does trichinellosis cause?
Many people with trichinosis have no symptoms at all. Persons who show symptoms usually have nausea, diarrhea, vomiting, fever, and abdominal discomfort. Headache, fever, chills, cough, swelling of the upper eyelids, aching joints and muscle pain, itchy skin, diarrhea, or constipation may occur after the first symptoms. If the infection is heavy, patients may have problems coordinating movements and have heart and breathing problems.

How common is trichinellosis?
Trichinosis is a common infection worldwide. Trichinosis is not only common in swine but also be found in dogs, cats, horses, rats, and in many wild animals, including fox, wolf, bear, polar bear, wild boar, marine mammals in the Arctic, hyena, jackal, lion, and leopard. In recent years, there have been recorded outbreaks traced to eating improperly cooked bear meat.

In the United States, infection was once very common; however, infection is now relatively rare. From 1991-1996, an annual average of 38 cases per year were reported. The number of cases has decreased because of legislation prohibiting the feeding of raw meat garbage to hogs, commercial and home freezing of pork, and the public awareness of the danger of eating raw or undercooked pork products. Cases are less commonly associated with pork products and more often associated with eating raw or undercooked wild game meats.

How is trichinellosis spread? How do people get trichinellosis?
The worm is spread when animals ingest infected animal flesh. Rats and other rodents maintain the infection in nature. Pigs and bears may eat the rodents, which, in turn, may infect humans.

Who should be especially careful about trichinellosis?
Anyone who eats undercooked meat of infected animals can develop trichinosis.

How do I protect myself from trichinellosis?
Thoroughly cook (to at least 170°F) all fresh pork and pork products. Other raw and undercooked meat should also be avoided, especially meat from wild animals.

Freezing infected meats at -13 °F for 10 days or longer will also kill the parasite; however, some cold resistant strains found in some Arctic wildlife cannot be killed this way.

How do I protect others from trichinellosis?
If processing meats, grind pork in a separate grinder or clean the grinder thoroughly before and after processing other meats.

What do I do if I think I have trichinellosis?
Consult your healthcare provider.

How are trichinellosis infections diagnosed?
Diagnosis of trichinosis in man is often difficult because symptoms usually don't occur until about a week after the infected meat is eaten; the clinical signs of the disease may be absent in the early stages and those noted in the later stages often simulate other diseases.

Trichinosis is diagnosed by a blood test or by a biopsy of the muscle to identify the parasite.

How is trichinellosis treated?
The healthcare provider will use specific drugs to treat trichinosis based on the severity of the disease and the condition of the patient.

Should I worry about trichinellosis when I travel out of the country?
Since trichinellosis is found worldwide, the traveler should observe the indicated precautions when eating meat.