What is trichinosis? What are symptoms of trichinosis?
Trichinosis (also termed trichinellosis, trichiniasis, or trichinelliasis) is a disease caused by parasites, called roundworms (Trichinella spp.), that can infect and damage many body tissues. Although the parasites can pass through the intestinal tract and other tissues, muscle tissues are where the majority of them persist. Trichinosis is usually characterized by two phases; the initial phase (intestinal) of abdominal discomfort, diarrhea, and nausea that begins one to two days after ingestion and the second phase (muscle) of muscle aches, itching, fever, chills, and joint pains that begins about two to eight weeks after ingestion.

What causes trichinosis?
Trichinosis is caused by Trichinella species (also termed parasitic nematodes, intestinal worms, and roundworms) that initially enter the body when meat containing the Trichinella cysts (roundworm larvae) is eaten. For humans, undercooked or raw pork and pork products, such as pork sausage, has been the meat most commonly responsible for transmitting the Trichinella parasites. It is a food-borne infection and not contagious from one human to another unless infected human muscle is eaten. However, almost any carnivore (meat eater) or omnivore (eats meat and plants for food) can both become infected and, if eaten, can transmit the disease to other carnivores and omnivores. For example, undercooked or raw bear meat can contain livable Trichinella cysts. Therefore, if humans, dogs, pigs, rats, or mice eat the meat, they can become infected. In rare instances, larvae that inadvertently reaches cattle feed can infect cattle. There are six species that are known to infect humans:

What is the history and life cycle of trichinosis?
The life cycle of this particular parasite is important in the way disease develops in humans. In 1835, J. Paget and R. Owen first discovered larvae of Trichinella in a piece of human muscle during an autopsy. That same year, R. Virchow and F. Zenker discovered the complicated lifecycle of Trichinella by feeding a dog Trichinella-infected meat.

In humans, the larvae are ingested, released from an encapsulated (encysted) cyst by stomach acid (except for the nonencapsulated T. pseudospiralis), and then develop into adult male and female worms in the gastrointestinal tract. The adult worms mate and then shed larvae that penetrate the gastrointestinal tract and reach the bloodstream and lymph drainage system. The larvae are then distributed to body cells (mainly skeletal muscle cells). Some skeletal muscle cells develop into nurse cells that support and protect the larvae from the host's immune system.

How is trichinosis treated?
Most trichinosis infections, according to the experts, are subclinical or have minor symptoms and do not require any treatment as they are self-limited (all symptoms resolve without treatment). In patients with more intense symptoms, thiabendazole (Mintezol) can be used to eliminate the adult worms in the gastrointestinal tract. Albendazole (Albenza) is another drug that may be used in some cases. The invasive and encysted larva forms of Trichinella species are treated by mebendazole (Vermox). Inflammation of infected tissues is usually treated with prednisone and is frequently used in combination with mebendazole.
 

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