Everything about Trichina Worm totally explained
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Trichinosis, also called
trichinellosis, or
trichiniasis, is a
parasitic disease caused by eating raw or undercooked
pork and
wild game 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, bear meat, or home reared pigs. It is most common in the developing world and where pigs are commonly fed raw garbage.
Signs and symptoms
Trichinosis initially involves the intestines. Within 1-2 days of contagion, symptoms such as
nausea,
heartburn,
dyspepsia, and
diarrhea appear; the severity of these symptoms depends on the extent of the infection. Later on, as the worms encyst in different parts of the human body, other manifestations of the disease may appear, such as
headache,
fever,
chills,
cough,
eye swelling,
joint pain and
muscle pain,
petechiae, and
itching.
Most symptoms subside within a few years. The most dangerous case is worms entering the
central nervous system. They can't survive there, but they may cause enough damage to produce serious neurological deficits (such as
ataxia or
respiratory paralysis), and even
death.
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 cell 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.
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's no treatment that kills the larva.
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 wasn't 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
(External Link
).
Infection was once very common, but is now rare in the
developed world. From
1997 to
2001, 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.
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
(External Link).
It has been suggested that trichinosis may be one of several factors that led to religious prohibitions in Islam, Judaism, etc. against eating pork products, such as in the
kashrut and
dhabiĥa halal dietary laws. The medieval Jewish philosopher
Maimonides advocated such a theory in his
Guide for the Perplexed.
This topic is controversial.
International Commission on trichinellosis
The
International Commission on Trichinellosis (ICT) was created in 1958 in Budapest and is aiming to exchange information on the biology, the physiopathology, the epidemiology, the immunology, and the clinical aspects of trichinellosis in humans and animals. Prevention is a primary goal. Since the creation of the ICT, its members (more than 110 from 46 countries) have regularly gathered and worked together during meetings held every 4 years : the
International Conference on Trichinellosis.
Prevention
