Trichinosis

Trichinosis is an intestinal worm infection. Intestinal worms are a type of parasite -- an organism that survives by feeding on other organisms or hosts. Parasites can inhabit the human body or live in soil, water, food or insects. Some parasites exist naturally in the human body, but are usually controlled by the immune system.


Causes/associated factors
Trichinosis (also known as trichiniasis and trichinellosis) is caused by the larvae of the intestinal roundworm Trichinella spiralis. Although relatively rare in the United States, the infection occurs worldwide and may affect the respiratory, nervous and cardiovascular systems.

Transmission
Trichinosis does not spread from person to person. Instead, it occurs after eating raw or undercooked meat that contains cysts (immature worms covered with a hard shell) of T. spiralis. Meat from pigs and wild boars or felines, horses, dogs, foxes, bears, seals and walruses has the highest risk of being infected. After eating the meat, your stomach acid releases the worms by dissolving the hard covering of the cysts. After a week, the cysts become mature adults and may live in the small intestine for another three to five weeks. During this time, the female worms release larvae (immature worms) that travel through the bloodstream to muscles throughout the body (commonly the jaw muscles used to chew, the diaphragm, and muscles of the chest, arms and legs). There, the larvae develop into cysts with hard shells, much like the cysts in infected meat.

Signs/symptoms
Symptoms may or may not be present. If symptoms do occur, they will vary depending on the location of the infection. The severity depends on the number of worms and cysts. Adult worms in the intestines may cause abdominal discomfort, nausea, vomiting, diarrhea and fever within the first week after ingesting the cysts. When the larvae invade other tissue, generally two to eight weeks later, symptoms may including swelling of the eyes or face, muscle and joint pain, itchy rash and fever. If there is a severe infection, potentially life-threatening heart, respiratory and nervous system symptoms may develop.

Diagnosis
The doctor will ask about meats you may have eaten and do a physical exam. A blood test may detect an unusually high concentration of eosinophils (a type of white blood cell known to destroy parasitic organisms) in your blood. It may be helpful to have a sample of the suspected meat checked for larvae. To confirm the presence of larvae in your system, you may need a muscle biopsy (taking a tissue sample for further examination) two weeks after infection.

Treatment
Trichinosis may be treated with the drugs mebendazole or albendazole. Infection can sometimes be prevented if medication is given during the first few days after eating infected meat. If you have muscle cysts the doctor may also prescribe corticosteroids (a type of anti-inflammatory medication).

Complications
Severe infections may lead to poor coordination or heart or lung problems. In extreme cases, trichinosis can be fatal.

Pregnancy-specific information
A variety of medications may be prescribed for various intestinal worm infections, but certain standard medications should not be taken if you're pregnant. Thoroughly discuss your health history with your doctor and review the risks and benefits of any treatment. If you don't have significant symptoms, your doctor may recommend postponing treatment until after delivery.
If you are or may be pregnant, you may want to avoid traveling to areas with poor sanitation, where you're more likely to develop parasitic infection(s). If you do travel to these areas, be sure to follow the preventive measures outlined below.


Senior-specific information
Growing older is not a risk factor for this condition.

Prevention
To prevent intestinal worms of any type, follow these general guidelines:
Practice sanitary hygiene habits, especially when disposing of human waste. Never wipe feces on the ground, and dispose of diapers properly.

Wear shoes in areas where the soil or sand may be contaminated with feces or parasites. Don't sit directly on the ground or handle the soil or sand with your bare hands.

Wash your hands thoroughly with soap and water or an antibacterial handwashing solution before handling food or water and after using the toilet or changing diapers.

Wash, peel or cook raw fruits and vegetables before eating.

Cook meat thoroughly, to at least 160°F. It should no longer be pink in the center. Measure the internal temperature to assure doneness. Keep in mind that curing, smoking, drying or microwaving meat may not kill all worms.

Slabs of pork less than 6 inches thick can be frozen at 5°F (-15°C) for 20 days to kill any worms. Freezing may not be effective for wild game.

If you're traveling abroad, it's wise to avoid uncooked fruits and vegetables, unless you've peeled them yourself; raw or undercooked meat, poultry, fish and eggs; foods prepared in advance that haven't been kept cold or very hot; and foods purchased from street vendors. If you have any doubts about a food's safety, follow this simple rule: Boil it, cook it, peel it or forget it.

If you're unsure of the safety of drinking water (such as in areas where the water isn't chlorinated or hygiene and sanitation are poor), ensure water safety by boiling your water vigorously for one minute, filtering it or treating it with iodine or chlorine. Drink only this water, beverages made from it, canned or bottled carbonated beverages (including water and soft drinks), beer or wine. Wash uncooked fruits or vegatables using treated or filtered water. Avoid using ice cubes and drinking from unclean glasses and wet or dirty cans or bottles. (It's best to drink straight from the can or bottle after wiping it clean and dry.) Don't brush your teeth in tap water, and avoid swallowing water while swimming or bathing.