Trichinosis is an infection with a particular roundworm parasite. It can occur as a result of eating raw or undercooked meat from infected animals. Infection may cause diarrhea, abdominal pain, and vomiting.
In the later stages of infection, people may also experience muscle pain or fever. In almost all cases, a person with trichinosis will require treatment with antiparasitic drugs.
In this article, we describe the causes, symptoms, and treatment of trichinosis.
Trichinosis, also known as trichinellosis, is an infection with a parasite called Trichinella. In humans, it starts in the stomach and small intestine. Due to the high infectivity of Trichinella and the global distribution of pork meat, trichinosis can occur in any part of the world.
Researchers estimate that globally, about 10,000 cases of trichinosis occur every year. Trichinosis is now fairly rare in the United States due to increased awareness, improvements in pig-raising practices, and home freezing of pork meat.
During 2011–2015, the Centers for Disease Control and Prevention (CDC) reported fewer than 20 cases per year, on average, in the U.S.
However, a person may still be at risk if they eat wild game, such as bear or walrus meat, that they or others have not frozen or cooked properly.
The severity of the symptoms that trichinosis causes may vary depending on the stage of the infection and the number of infectious worms that the person consumed in the meat. Some people may not experience any symptoms at all.
The first symptoms usually occur 1–2 days after eating the infected meat. People may experience:
- mild diarrhea
- abdominal pain
The following symptoms may occur within 2 weeks of eating the contaminated meat and may last for up to 8 weeks:
T. spiralis is the species that a person is most likely to find in pork meat. As distributors sell pork meat globally, trichinosis has a wide distribution.
Other species of Trichinella, such as T. britovi and T. papuae, can also cause human disease.
After a person ingests the parasites, the larvae enter the small intestine, where they mature and reproduce. The female worms then release larvae that migrate from the small intestine into the circulation to reach the muscles. Once in the muscles, the worms can live for an extended period.
Doctors may find diagnosing trichinosis challenging because the symptoms are similar to those of other intestinal disorders. People may also confuse the symptoms with those of the flu or other common illnesses.
People with trichinosis will develop antibodies against the parasite, which doctors can detect in a blood test. In severe trichinosis, muscle biopsy samples may contain Trichinella.
If a doctor suspects that a person’s symptoms may be from a foodborne infection, they will ask the person about their consumption of raw or undercooked meat.
Most people with trichinosis will require a prescription medication to treat the parasite infection and the associated symptoms.
Once a doctor has confirmed the diagnosis, they will begin treatment immediately. Treating trichinosis within the first 3 days of infection can prevent muscular invasion and disease progression.
As Trichinella is a helminth (parasitic worm), a doctor will prescribe an antihelminthic drug, such as albendazole or mebendazole. Mild infections can resolve within 2–6 months with appropriate treatment.
Some people may not require treatment, as the infection can disappear by itself within several months. However, a lack of treatment may result in a severe infection. People with a severe infection, such as those with cardiac or cerebral complications, have a poor outlook. The mortality rate among these individuals is 5%.
People can become infected by eating raw or undercooked meat from infected animals, particularly wild game or pork. Doctors suggest that even small amounts of contaminated meat put people at risk of infection.
Although anyone can become infected with a foodborne infection, certain people are more at risk. These include:
- adults aged 65 years and older
- children younger than 5 years
- people with a weakened immune system
- pregnant women
Some people report complications of trichinosis after successful treatment. These may include:
- menstrual irregularities
- hearing disorders
- weight loss
- hair and nail loss
- skin peeling
- loss of the ability to speak
- muscle stiffness
In people with a severe infection, complications may include:
- heart failure
- central nervous system failure
- inflamed lungs
- inflammation of the brain
- inflammation of the heart
- low blood potassium
- blood vessel obstruction
- adrenal gland insufficiency
Some people may experience long-term complications, such as:
- generalized muscle pains
- eye symptoms
To prevent trichinosis, the CDC note that people must cook meat to safe temperatures. A food thermometer can help people determine when meat is fully cooked. The CDC also suggest:
- washing the hands with warm water and soap after handling raw meat
- freezing pork less than 6 inches thick for 20 days at 5°F (-15°C)
- cleaning meat grinders thoroughly after each use
People who get sick from eating raw or undercooked meat should speak with a doctor.
Once the doctor has diagnosed the infection, they will determine the best treatment plan.
Anyone experiencing complications after recovering from trichinosis should also speak with a doctor.
Trichinosis is an intestinal infection that occurs when people eat raw or undercooked meat contaminated with a species of Trichinella, a parasitic roundworm.
People with trichinosis may experience nausea, vomiting, and diarrhea. In more severe or advanced cases, people may experience serious symptoms involving the heart or brain.
People with trichinosis require medical attention. Treatment includes antihelminthic drugs and medications to treat symptoms of the infection.