Trichinosis

Trichinosis
Other names	Trichinellosis, trichiniasis
Trichinella larvae in pressed bear meat, partially digested with pepsin. The classic coil shape is visible.
Specialty	Infectious disease
Symptoms	Initially: diarrhea, abdominal pain, vomiting[1] Later: swelling of the face, inflammation of the whites of the eyes, fever, muscle pains, rash[1]
Complications	Inflammation of heart muscle, inflammation of the lungs[1]
Causes	Trichinella from eating undercooked meat[1]
Diagnostic method	Antibodies in the blood, larvae on tissue biopsy[1]
Differential diagnosis	Measles, dermatomyositis, gastroenteritis[2]
Prevention	Fully cooking meat[3]
Medication	Albendazole, mebendazole[4]
Prognosis	Low risk of death[5]
Frequency	~10,000 cases a year[6]

Trichinosis, also known as trichinellosis, is a parasitic disease caused by roundworms of the Trichinella type.^[1] During the initial infection, invasion of the intestines can result in diarrhea, abdominal pain, and vomiting.^[1] Migration of larvae to muscle, which occurs about a week after being infected, can cause swelling of the face, inflammation of the whites of the eyes, fever, muscle pains, and a rash.^[1] Minor infection may be without symptoms.^[1] Complications may include inflammation of heart muscle, central nervous system involvement, and inflammation of the lungs.^[1]

Trichinosis is mainly spread when undercooked meat containing Trichinella cysts is eaten.^[1] In North America this is most often bear, but infection can also occur from pork, boar, and dog meat.^[7] Several species of Trichinella can cause disease, with T. spiralis being the most common.^[1] After the infected meat has been eaten, the larvae are released from their cysts in the stomach.^[1] They then invade the wall of the small intestine, where they develop into adult worms.^[1] After one week, the females release new larvae that migrate to voluntarily controlled muscles, where they form cysts.^[1] The diagnosis is usually based on symptoms and confirmed by finding specific antibodies in the blood, or larvae on tissue biopsy.^[1]

The best way to prevent trichinosis is to fully cook meat.^[3] A food thermometer can verify that the temperature inside the meat is high enough.^[3] Infection is typically treated with antiparasitic medication such as albendazole or mebendazole.^[4] Rapid treatment may kill adult worms and thereby stop further worsening of symptoms.^[4] Both medications are considered safe, but have been associated with side effects such as bone marrow suppression.^[4] Their use during pregnancy or in children under the age of 2 years is poorly studied, but appears to be safe.^[4] Treatment with steroids is sometimes also required in severe cases.^[4] Without treatment, symptoms typically resolve within three months.^[5]

Worldwide, about 10,000 infections occur a year.^[6] At least 55 countries including the United States, China, Argentina, and Russia have had recently documented cases.^[5] While the disease occurs in the tropics, it is less common there.^[5] Rates of trichinosis in the United States have decreased from about 400 cases per year in the 1940s to 20 or fewer per year in the 2000s.^[6][8] The risk of death from infection is low.^[5]