Toxoplasma contamination of food

作者：admin  点击次数：19  发布时间：2025-04-09

Toxoplasma gondii is an intracellular parasitic protozoan with a wide range of host species. Toxoplasmosis caused by it is a zoonotic parasitic disease with a worldwide distribution. 25% to 50% of people are infected worldwide, and most of them are latent infections.
1. Pathogens
Toxoplasma belongs to the Toxoplasma family and the Toxoplasma genus. Its development process requires coccidia development in the intestines of the final host (feline and lynx) and toxoplasma development in the intermediate host (human, mammal and bird). There are 5 stages: trophozoite stage, cyst stage, schizont stage, gametocyte stage and egg stage. The morphological structure of Toxoplasma gondii in each development stage is completely different. Trophozoites are the proliferative form of Toxoplasma gondii, which are banana-shaped or arch-shaped, (3.5~8)mx(1.5~4)μm. Cysts are often found in the brain, myocardium and skeletal muscle, with a size of 10~200wm, containing parasites, up to 3,000 in number. After the cysts are formed, they can survive in the host for several years. 2. Causes and clinical symptoms
No matter how Toxoplasma enters the human host, it must spread through the bloodstream to the whole body. The ways in which humans are infected with Toxoplasma include: contact with and eating raw meat of livestock and poultry (pigs, cattle, sheep, chickens, ducks, rabbits, etc.) with this disease; oral infection through cat feces contaminating food, water sources and hands; Toxoplasma gondii in the sputum and saliva of cats and dogs, and when in contact with them, hands and faces can be infected by licking them; pregnant women infected with Toxoplasma gondii can be transmitted to the fetus through the placenta; they can also be infected through insect bites, blood transfusions, etc. Most toxoplasmosis is latent infection, and only a few infected people develop the disease. The clinical manifestations of toxoplasmosis depend on the parasitic site and the body's reactivity. Congenital toxoplasmosis: causes malformed fetuses or stillbirths. Acquired toxoplasmosis: Common symptoms include fever, discomfort, night sweats, muscle pain, throat pain, rash, etc. Some patients also experience lymphadenopathy, myopericarditis, hepatitis, arthritis, nephritis and encephalopathy.
3. Preventive measures
Strengthen the meat hygiene inspection and processing system; for those engaged in animal husbandry and meat food processing, regular serological examinations should be conducted; feces should be harmlessly treated; rodent control should be carried out; pets such as cats should not be kept; raw eggs, raw milk and uncooked meat should not be eaten, and raw and cooked utensils should be strictly separated.
(VI) Contamination of food by amoeba
There are many types of amoeba, and it is generally believed that only Entamoba hitolytica has the ability to invade tissues. Therefore, anyone infected by Entamoeba histolytica, whether or not they have symptoms, is called amebiasis. According to literature reports, there are about 300 million patients worldwide, and the death toll is as high as 100,000 people each year.
1. The pathogen Entamoeba histolytica has three forms: cysts and large and small trophozoites. Large trophozoites parasitize in tissues such as the submucosal layer of the colon, multiply by binary fission, have one nucleus with a diameter of 20~40um, are invasive, and are mainly found in the feces of patients in the acute phase; small trophozoites mainly parasitize in the intestinal cavity, with a diameter of 6~20um; the diameter of the cyst is 10~16um, and the mature 4-nucleus cyst is infectious. It matures within 6 hours after entering the host and is excreted with feces, with a daily excretion of up to 1 million. Trophozoites are very likely to die when excreted from the body and have no transmission effect. The cysts have strong resistance in the external environment. They can survive in feces for 2 weeks, in water for 5 weeks, and in common disinfectants for 20-30 minutes. The concentration of general drinking water disinfection cannot kill them, but they can be killed at 60°C and 10 minutes.
2. Causes of disease and clinical symptoms People or animals (mainly domestic pigs and hamsters) with chronic recovery period of amoebiasis and asymptomatic cyst excretion are the source of infection. After the excrement containing cysts directly contaminates water sources and food or indirectly contaminates food through fly feces, it is transmitted orally. After the histolytica entamoeba invades the human body, most infected people are asymptomatic carriers. After entering the stomach and reaching the small intestine, the cysts are released, and they divide and multiply by binary fission, which can invade the intestinal mucosa and form ulcers on the intestinal wall, i.e. intestinal amoebiasis (also called amoebic dysentery). It is clinically divided into asymptomatic type, common type, fulminant type, chronic type and intestinal and extraintestinal complications, with diarrhea and bloody stool as the main symptoms; it can also break through the blood vessels of the intestinal ulcer wall and enter the blood to cause extraintestinal amoebiasis (mainly amoebic liver abscess), with clinical manifestations of long-term irregular fever, weight loss, enlarged liver and pain in the liver area.
3. Preventive measures People with cysts are the main source of infection in the population, and the three controls (control of diet, control of drinking water, and control of feces) and one elimination (elimination) should be strengthened; food hygiene publicity and education should be strengthened to prevent "disease from the mouth"; animals naturally infected with amoeba should be prevented from directly or indirectly contaminating food.