Trichinosis (cont.)

For those who have minor or no symptoms, the prognosis is excellent with no complications. For the minority of patients that develop complications, the prognosis is still good as most will recover and the symptoms will decrease and disappear. However, for a few patients, the prognosis is less clear as complications, especially those with the brain disease, which may persist for many years. Less than 0.1%-0.3% patients with trichinosis die from the disease.

The major risk factor for contracting trichinosis is eating raw or undercooked pork or wild game such as bear meat, wild boar meat, or other carnivore or omnivore meat. The risk of developing infection is related to the amount of larvae ingested. About 10 larvae per gram of meat (muscle) ingested result in a mild infection, about 50-500 result in a moderate infection while over 1,000 result in a severe infection. Consequently, reducing or eliminating the number of larvae in infected meat reduces both the risk and severity of infection. This is accomplished by cooking meat to a uniform temperature of 70 degrees Celsius (158 degrees Fahrenheit) or higher for at least a few minutes to kill encysted larvae. Freezing of pork meat to a temperature of -30 degrees Celsius (-22 degrees Fahrenheit) for one week reportedly kills the encysted larvae. However, this freezing technique for wild game meat may not be effective, as Trichinella in wild animals is usually not as susceptible to freeze killing. Other cooking methods such as microwaving, smoking, or salting meat often fail to kill the encysted larvae and thus the risk of getting trichinosis from meat treated by these methods is increased.

Trichinosis is a common disease in many wild carnivorous and omnivorous animals worldwide, except for Australia. Because of strict measures by the meat (pork) industry and public-health authorities, especially in developed countries, the incidence of disease in humans has dropped dramatically in the last few decades. For example, the United States has averaged only about 12-20 cases per year in the last two decades. However, there are outbreaks that occur sporadically in the world when meat (especially pork) is improperly cooked or is contaminated with undercooked or raw wild-game meat. If the source of the outbreak is a meat supplier, hundreds of people can be infected as was the situation that occurred in Poland in 2007.

Source: MedicineNet.com
http://www.medicinenet.com/trichinosis/article.htm