Prevention and control of porcine meat sporangiasis

Prevention and control of porcine meat sporangiasis

Yu Liling

Swine meat sporangiasis is a parasitic disease that lives in the muscle tissues of pigs and in dogs, cats and human intestinal epithelial tissues, which is endemic worldwide, and there are a large number of insect bodies in the muscles of infected pigs, which can also cause human infection and affect food safety. This patient is zoonotic, and the prevention of this disease has important public health significance.

1 Pig-dwelling sporangia

There are 3 common clinical species of swine-dwelling sporidium, namely pig dog-dwelling sporangia, pig cat-dwelling sporangia, and pig-man-dwelling sporangia. Throughout the life history, pigs play the role of intermediate host, clinically common porcine sporidium is parasitic between muscle tissue and parallel to the muscle fibers of the cyst, this cyst technical term is called "Mishuel sac", the length of 0.5 ~ 4.0 mm, the appearance of 2 layers of membrane, gray or milky white, the inner membrane extends to the inside of the cyst cavity, forming a lot of septum and chamber, there are many active trophozoites in the chamber, also known as "Nanlei small body". The trophozoites are banana-shaped and (5.0 to 16.0) μm in size× (2.0 to 3.5) μm in size, with a slightly pointed end and a slightly blunt circle at the other. After the trophozoite is stained with Reye's stain, its central nucleus is dark purple-red, the cytoplasm is light blue, and the color difference is more obvious.

2 Developmental history

If the pig is infected, there is a large number of carnithosporidiums in its muscle tissue, which exist in the muscle tissue in the form of a trophoblast, and if the pork is not fully cooked, or if it is directly fed raw to dogs and cats, it will lead to infection of people or dogs and cats. After the insect body cyst enters the digestive tract, gamete reproduction is carried out in the intestinal epithelial tissue cells, and the female gamete and male gamete combine to form zygotes, and the zygotes gradually develop to form oocysts. After a period of sporeization, the oocyst eventually turns into a sporosporosis oocyst containing 2 sporospores and excreted with feces, polluting the environment. If the sporeized oocyst is accidentally eaten by pigs, the sporozoites will enter the blood vessels through the intestine, and the vascular endothelial cells undergo fissured reproduction, and finally form schizonts and mesozoites, and at a certain stage, some of the schizoites enter the striated muscle tissue, and gradually develop into trophoblasts and muscle sacs, regaining infectivity, forming an infectious threat to humans, dogs, cats and other animals.

3 Clinical symptoms and pathological lesions

Typically, when mildly infected, pigs do not show any symptoms of discomfort and are not easily detected clinically [3]. In severe infection, pigs present with decreased feed intake, general anemia, restlessness, muscle stiffness, changes in walking posture, ataxia, dyspnea, general hypoxia, cyanosis of the visible mucosa, and even paralysis of the hind limbs. Long-term anorexia can cause the pig body to gradually weaken, reduce immunity, and easily secondary infection with other pathogens. If a sow is infected during pregnancy, it will miscarry at an early stage, and if it is infected in the second trimester, it will give birth to a mummy fetus, and later infection will lead to stillbirth or the birth of weak litters.

On the autopsy of sick and dead pigs, it can be seen that there are a large number of milky white or gray cysts in the muscle tissue of the pig, some of which have calcified, the touch is hard, the inside is a small black mass, and the muscle tissue distributed by a large number of cysts is seriously denatured, and the color is light like boiled meat. Infection occurs in all muscular tissues of the body, but the diaphragm, intercostal muscles, esophageal walls, tongue, throat, heart, pectoral muscles, and abdominal muscles have the most cysts.

4 Prevention

To prevent this disease, we must strengthen the supervision of food safety, cut off the transmission route of the disease, and scientifically use drugs for prevention and control.

4.1 Strengthen food safety supervision

This patient is zoonotic, once the infection will lead to the occurrence of enteritis, the slaughterhouse must strengthen the inspection and quarantine of the disease, find the pork infected with the bag, and destroy it in strict accordance with the regulations. When consumers choose pork and its products, try to buy it in large supermarkets or regular wet markets, not from small traders. When eating pork products, we must ensure that they are cooked thoroughly, and the high temperature has a killing effect on the bag and can prevent itself from being infected. If you accidentally eat unhygienic pork, go to the hospital in time for medical treatment.

4.2 Cut off the route of transmission

Pig farms should try not to raise dogs, cats and other animals, if they must be raised, try to use ropes to tie in a fixed place, prohibit them from entering the production area, and prevent the feeding of raw pork and its products. Pig farms that have had this disease must be thoroughly cleaned and disinfected inside and outside the farm, and the empty house time is not less than 30 days. The newly introduced pigs clean up their manure every day, try to use dry manure, and the manure is composted and fermented more than 200 meters away from the production area, and the biothermal heat generated during the composting process is used to kill the insects. It is forbidden to introduce pigs from pig farms in the epidemic area, and front-line production employees in farms are prohibited from visiting pig slaughterhouses, livestock and poultry trading markets and other places to reduce the chance of infection of the disease.

4.3 Drug prevention and control

At present, there is no specific vaccine prevention and no specific treatment drugs for this disease, but clinical experience shows that drugs such as saltmycin, monensycin, and amphetamine can play a certain inhibitory effect on the development of insects and can be used for the prevention and treatment of this disease. On the day after the introduction of pigs in pig farms in endemic areas, drugs can be added to the feed for continuous use for 3 days to prevent insect infection in the environment. Pig farms in non-epidemic areas must strengthen the monitoring of the disease, isolate and confirm the suspected cases at the first time, and strengthen the prevention and control of the whole site.

5 Discussion

With the continuous large-scale and intensive development of China's aquaculture industry, the management level of pig farms has been greatly improved, such as the incidence of tissue parasitic diseases such as swine meat sporangiasis is also declining, coupled with the continuous maturity of food inspection and quarantine methods and the strict implementation of food safety laws, the probability of this type of zoonotic disease is very small. The difficulty of the prevention and control of this disease is that many mildly infected pigs do not show symptoms clinically, it is easy to enter the market as a healthy pig slaughter, even if the seriously infected pigs, their clinical manifestations are similar to many diseases, it is easy to misdiagnose, so it is very important to strengthen the supervision of terminal meat products, because the meat after slaughter if there is an insect infection, it can be identified through the naked eye or with the help of a microscope. In addition, as a consumer to buy back from the market meat, must be cooked thoroughly at high temperature before eating, for their own health to make a good last pass.