Filed under: Infectious Diseases
Trichinosis (trik-ih-NO-sis), sometimes called trichinellosis, is a type of roundworm infection. Roundworms are parasites that use a host body to stay alive and reproduce. Trichinosis occurs primarily among meat-eating animals (carnivores), especially bears, foxes and walruses. Trichinosis infection is acquired by eating larvae in raw or undercooked meat.
When humans eat undercooked meat containing trichinella larvae, the larvae mature into adult worms in the intestine over several weeks. The adults then produce larvae that migrate through various tissues, including muscle. Trichinosis is most widespread in rural areas throughout the world.
Trichinosis can be treated with medication, though it's not always necessary. It's also easy to prevent.
Abdominal symptoms can occur within two to seven days of infection. Other symptoms usually start one to eight weeks later. Severity of symptoms usually depends on the number of larvae consumed in the infected meat.
Possibly no signs or symptoms
Mild cases of trichinosis — those with only a small number of parasites in your body — may cause no recognizable symptoms. Symptoms can develop with moderate or heavy infestation, sometimes progressing as the parasite migrates through your body.
Initial signs and symptoms
You swallow trichinella larvae encased in a cyst. Your digestive juices dissolve the cyst, releasing the parasite into your body. The larvae then penetrate the intestine, where they mature into adult worms and mate. At this stage, you may experience:
Later signs and symptoms
About a week after infection, the adult female worms produce larvae that penetrate the intestinal wall, enter your bloodstream, and eventually burrow into muscle or other tissue. This tissue invasion can cause:
When to see a doctor
If you have a mild case of trichinosis with no symptoms, you may never need medical attention. If you notice gastrointestinal problems or muscle pain and swelling about a week after eating pork or wild-animal meat, talk to your doctor.
There is no effective treatment to eliminate trichinella once larvae invade tissue. At that point, treatment is for symptoms only until the parasites die on their own.
People get trichinosis when they eat undercooked meat — such as pork, bear, walrus or horse — that is infected with the immature form (larvae) of the trichinella roundworm. In nature, animals are infected when they feed on other infected animals. Pigs and horses can become infected with trichinosis when they feed on garbage containing infected meat scraps. Other cases have been linked to eating beef that was mixed with infected pork or ground in a grinder previously used for contaminated pork.
Due to increased regulation of pork feed and products in the United States, pigs have become a less common source of infection. Wild animals, including bear, continue to be sources of infection.
Risk factors for trichinosis include:
Except in severe cases, complications related to trichinosis are rare. In cases of heavy infestation, larvae can migrate to vital organs, causing potentially dangerous complications, including:
You're likely to start by seeing your family doctor or a general practitioner. In some cases, you may be referred to an infectious disease specialist.
To get the most from your appointment, it's good to be well prepared. Here's some information to help you.
What you can do
Preparing a list of questions will help you make the most of your time with your doctor. For trichinosis, some basic questions to ask your doctor include:
Don't hesitate to ask any other questions.
What to expect from your doctor
Your doctor is likely to ask you a number of questions, including:
Trichinella larvae bury themselves inside muscle tissue rather than remain in the intestine as in other roundworm infections, so stool sample tests don't often show evidence of the parasite. The initial diagnosis relies on the classic signs and symptoms — swelling around the eyes, muscle inflammation and fever. To confirm the diagnosis, your doctor may use these tests:
Trichinosis usually isn't serious and often gets better on its own, usually within a few months. However, fatigue, mild pain, weakness and diarrhea may linger for months or even years. Symptomatic infections may respond to treatment with medication.
The best defense against trichinosis is proper food preparation. Follow these tips to avoid trichinosis: