【Pathogen】Swine trichinellosis is a general term for intestinal trichinellosis and myotrahizoliosis caused by adult and larvae of trichinella of the suborder Trichocetes, which are parasitic in the small intestine and rhabdomy muscles. According to the relevant literature, nearly 100 species of mammals can be infected with trichinellosis. Under natural conditions, the disease is more common in pigs and rodents, but also in dogs, cats and a variety of wild animals (bears, foxes, wolves, badgers, wild boars, mink, etc.), and occasionally cattle and sheep are also infected (the first time in our province), which can cause endemic epidemics. In areas where pigs suffer from trichinellosis, the disease is also common and often causes death. Therefore, trichinellosis is a worldwide severe parasitic disease that is common to humans and animals.
Regarding the transmission route of swine trichinellosis, it has been documented that pigs are infected by eating trichinellosis rodents or meat scraps. In recent years, it has been said that it has been infected by eating the excrement of sick rats and pigs. According to the relevant investigation materials in the United States, pigs fed leftovers from soups eaten by uncooked people, waste meat from slaughterhouses, grains or leftover meat scraps can be infected with the disease. According to the relevant investigation materials of our province, the way of infection of this disease is to feed and wash meat, and the second is that pigs eat the feces of sick people and animals and the corpses of livestock.
The incidence of swine trichinellosis is seasonal. According to the test, the first quarter is low, the second quarter is up, the third quarter is the peak, and the fourth quarter is down. Pig infection with trichinellosis is mainly around the Spring Festival and Mid-Autumn Festival. Because of these two traditional festivals (especially the Spring Festival), the countryside eats more meat, so it is the "peak season" for pig infection. The law of transmission is: infection in a vicious circle at the source of the epidemic and spread along the direction of rivers and meat flow. The adult spinolina is a slender nematode with males 1.4 to 1.6 mm long and females 3 to 4 mm long. The larvae parasitizing the muscles can reach up to 1.15 mm and curl up between the muscle fibers to form a cyst. The blunt circles at both ends of the capsule are fusiform and about 0.5 to 0.8 mm long.
After the pig eats a rodent or meat chip with myotra, the cyst dissolves in the stomach, and the larvae escape from the cyst, stay in the duodenum and jejunum, and become a sexually mature trichinella after two days. After mating in the intestinal lumen, the male dies, and the fertilized female burrows her head into the intestinal mucosa and begins to produce a large number of larvae on days 5 to 6, dying after the end of the wormbirth. The female has a lifespan of about 25 to 45 days, and a female can produce 1,500 to 10,000 larvae. The larvae enter the bloodstream through the lymph, then grow and develop within the striated muscles, gradually curling up into a spiral, and forming a cyst around it. After a few months, the cyst begins to calcificiate, but the larvae in the cyst remain infested for up to 25 years. Spinchinella is highly resistant to external undesirable factors. Intestinal trichinellosis and myotrazoansis occur sequentially in animals, so the same animal is both its intermediate host and its terminal host, so trichinella is a permanent parasite.
【Symptoms】 When pigs are naturally infected, most do not show symptoms, because pigs have a strong tolerance to trichinella. The influence of the worm body on the gastrointestinal tract is minimal, and the main changes are in the muscles, such as the disappearance of the rhabdomyosis of muscle cells, atrophy, thickening and proliferation of the muscle fiber membrane. In severe infections, the body temperature rises, diarrhea, sometimes vomiting, the affected pigs are emaciated, breathing difficulties, hoarseness of pronunciation. In artificially infected pigs, the main symptoms are loss of appetite, severe muscle pain, hindlimb paralysis, frequent urination, muscle stiffness, itching, etc.
Autopsy examination: spinatiles of muscles are mostly parasitic in the striated muscle, of which the parasitism is mostly in the diaphragm muscle, and the intercostal muscle, tongue muscle, laryngeal muscle, neck muscle, etc., because it can destroy the striated muscle, so the rhabdomyosa disappears. After forming a cyst, the trichinella becomes a tiny ovoid lesion in the muscle. Typical cysts, such as the size of a needle tip, protrude slightly on the surface of the muscle. At first, the capsule is dewdrop-shaped, translucent, and less muscular, and then gradually becomes pale grayish white, milky white, yellowish white.
【Prevention and control】Strengthen the hygiene inspection of meat after slaughter. The method is to take one piece of the left and right corners of the diaphragm "or psoas muscles and abdominal muscles", cut off a total of 24 small pieces of wheat grain, press thinned side by side in the glass pressure plate for examining trichinella, and then use a low magnification (40 to 50 times) microscopy. In the 24 tablets, if no more than 5 live or calcified trichinella or sacs are found, the flesh can be eaten after high temperature treatment; more than 5, the flesh, heart, esophagus and throat are used for industrial use or destruction. Subcutaneous and intermuscular fats can be refined into edible oils. Intestines can be made of casings. Other offal are not restricted.
Prevention should be focused on this disease. Strengthen the feeding and management of pigs and enhance their disease resistance. Earnestly do a good job in the work of eliminating rats in pig houses, feed processing houses, and slaughterhouses. Cooked food is advocated, and it is strictly forbidden for people to eat raw pork or half-cooked pork. Patients should be found to have a clear understanding of the epidemic situation in a timely manner and effective prevention and control measures should be taken. There is currently no effective treatment for this disease, and thiazole or diphthiazole and pyrazone can be tried.
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