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Trichinosis

2007 Schools Wikipedia Selection. Related subjects: Health and medicine

   CAPTION: Trichinosis
   Classifications and external resources

    ICD- 10   B 75.
     ICD- 9   124
   DiseasesDB 13326

   Trichinosis, also called trichinellosis, or trichiniasis, is a
   parasitic disease caused by eating raw or undercooked pork and wild
   game products infected with the larvae of a species of roundworm
   Trichinella spiralis, commonly called the trichina worm. The few cases
   in the United States are mostly the result of eating undercooked game
   or home reared pigs. It is most common in the developing world and
   where pigs are commonly fed raw garbage.

Signs and symptoms

   Symptoms can be divided into two types: symptoms caused by worms in the
   intestine, and symptoms caused by worms elsewhere.

   In the intestine, infection can cause:
     * Nausea, diarrhea, vomiting, fatigue, fever, and abdominal
       discomfort

   Later, as the worms encyst in different parts of the body, other
   symptoms occur such as:
     * Headaches, fevers, chills, cough, eye swelling, aching joints and
       muscle pains, pinpoint hemorrhages, itchy skin, and heightened
       numbers of white blood cells.

   If worms penetrate nervous tissue, they cannot survive, but patients
   may experience difficulty coordinating movements and respiratory
   paralysis. In severe cases, death may occur. Heart infection can also
   cause death.

   For mild to moderate infections, most symptoms subside within a few
   months. Fatigue, weakness, and diarrhea may last for months.

Incubation time

   Abdominal symptoms can occur 1–2 days after infection. Further symptoms
   usually start 2–8 weeks after eating contaminated meat. Symptoms may
   range from very mild to severe and relate to the number of infectious
   worms consumed in meat, and the amount of meat consumed. Often, mild
   cases of trichinosis are never specifically diagnosed and are assumed
   to be the flu or other common illnesses.

Life cycle

   The worm can infect any species of mammal that consumes its encysted
   larval stages. When an animal eats meat that contains infective
   Trichinella cysts, the acid in the stomach dissolves the hard covering
   of the cyst and releases the worms. The worms pass into the small
   intestine and, in 1–2 days, become mature. After mating, adult females
   produce larvae, which break through the intestinal wall and travel
   through the lymphatic system to the circulatory system to find a
   suitable cell. Larvae can penetrate any cell, but can only survive in
   skeletal muscle. Within a muscle cell, the worms curl up and direct the
   cells functioning much as a virus does. The cell is now called a nurse
   cell. Soon, a net of blood vessels surround the nurse cell, providing
   added nutrition for the larva inside.

Screening for compounds active against Trichinella

   (1) An in vitro screening test for compounds active against the
   parenteral stages of Trichinella spiralis.

   Tropenmed Parasitol. 1981 Mar; 32(1): 31-4. (Jenkins DC, Carrington
   TS.)

   A new in vitro screening test for compounds showing activity against
   the tissue stages of Trichinella spiralis is described Freshly
   decapsulated larvae of the parasite are exposed to low concentrations
   of experimental compound in a medium capable of supporting the partial
   development of the worms. The screen detects the activity of those
   compounds known to be effective against the parenteral stages of the
   parasite.

   (2) Trichinella pseudospiralis as a model for the "in vitro" screening
   of anthelmintics. Wiad Parazytol. 1986; 32(3): 303-11. (Gomez-Barrio A,
   Bolas-Fernandez F, Martinez-Fernandez AR.)

   .

Diagnosis

   A blood test or muscle biopsy can identify trichinosis. Stool studies
   can identify adult worms, with females being about 3 mm long and males
   about half that size.

Treatment

   Symptoms can be treated with aspirin and corticosteroids. Thiabendazole
   can kill adult worms in the intestine; however, there is no treatment
   that kills the larvae.

Epidemiology

   Trichinosis was known as early as 1835 to have been caused by a
   parasite, but the mechanism of infection was unclear at the time. It
   was not until a decade later that American scientist Joseph Leidy
   pinpointed undercooked meat as the primary vector for the parasite, and
   not until two decades afterwards that this hypothesis was fully
   accepted by the scientific community .

   Infection was once very common, but is now quite rare in the developed
   world. From 1991 to 1996, an annual average of 12 cases per year were
   reported in the United States. The number of cases has decreased
   because of legislation prohibiting the feeding of raw meat garbage to
   hogs, increased commercial and home freezing of pork, and the public
   awareness of the danger of eating raw or undercooked pork products.
   Today, one of the primary causes of trichinosis in America is the
   consumption of raw or undercooked wild game meats.

   In the developing world, most infections are associated with
   undercooked pork. For example, in Thailand, between 200 and 600 cases
   are reported annually around the Thai New Year. In parts of Eastern
   Europe, the WHO reports that some swine herds have trichinosis
   infection rates above 50%, and there are correspondingly large numbers
   of human infections .

   It has been suggested that trichinosis may be one of several factors
   that led to religious prohibitions against eating pork products, such
   as in the kashrut dietary laws. The medieval Jewish philosopher
   Maimonides advocated such a theory in his Guide for the Perplexed. This
   topic is controversial.

Prevention

     * Cooking meat products until the juices run clear or to an internal
       temperature of 144 ° F (62 ° C).
     * Freezing pork less than 6 inches thick for 20 days at 5 °F (−15 °C)
       or three days at −4 °F (−20 °C) kills larval worms.
     * Cooking wild game meat thoroughly. Freezing wild game meats, unlike
       freezing pork products, even for long periods of time, may not
       effectively kill all worms. This is because the species of
       trichinella that typically infects wild game is more resistant to
       freezing than the species that infects pigs.
     * Cooking all meat fed to pigs or other wild animals.
     * Not allowing hogs to eat uncooked carcasses of other animals,
       including rats, which may be infected with trichinosis.
     * Cleaning meat grinders thoroughly when preparing ground meats.
     * Public control and destruction of pork meat with trichins, ie
       control each pigs diaphragma before allowing it to be sold to the
       public.

   Curing (salting), drying, smoking, or microwaving meat does not
   consistently kill infective worms.
   Retrieved from " http://en.wikipedia.org/wiki/Trichinosis"
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