Basic knowledge of schistosomiasis control 1. Knowledge of schistosomiasis control

The epidemic situation of schistosomiasis in China is serious, widely distributed and complicated. Based on decades of prevention and control practice and scientific research, the current prevention and control strategies and measures of schistosomiasis in China have been formulated, and the policy of comprehensive management and scientific prevention and control according to local conditions has been put forward.

1. Check patients and sick cows to eliminate the source of infection.

00 patients need stool examination eggs or hatched miracidium. With the deepening of schistosomiasis control, it is more and more difficult to detect eggs in feces, so the detection methods are constantly improved and a series of serological diagnosis methods are put forward, which are more and more perfect, simple and effective. In the field of large-scale census, comprehensive disease detection methods can be adopted according to the actual situation. Cattle is an important pest control host, which can not be ignored in pest control. Patients and sick cows should be treated in time when they are found. Praziquantel was synthesized in China in 1970s. It is a safe, effective and convenient therapeutic drug. Advanced patients are often treated with traditional Chinese medicine first, then with pesticides or surgery.

2. Control and eliminate snails

00 plain water network area and some hilly areas mainly produce water conservancy combined with snail control, and locally cooperate with the application of snail control drugs. Lake and marsh areas mainly control the water level and change the snail breeding environment. We must take effective measures according to local conditions, from controlling snails to reducing snail density, and finally eliminate snails. In some areas, the key to taking chemotherapy combined with important snail control measures is to find the susceptible area and carry out snail control in the susceptible area.

3. Strengthen feces management and personal protection.

Combined with the patriotic health campaign in rural areas, we should manage human and animal feces to prevent water pollution. Such as the construction of harmless septic tanks and the mixed storage of manure and urine. In recent years, the popularity of biogas digesters has opened up a new way for manure management. Repeatedly killing snails in susceptible areas to achieve safe water use. Personal protection can be strengthened by applying protective drugs or oral preventive drugs during the epidemic season. In addition, it is also very important to strengthen publicity and education, especially health education for susceptible people, and guide people's behaviors, habits and working methods to pay attention to self-care. Schistosomiasis has been prevalent in China for a long time. Large-scale irrigation and water conservancy infrastructure and a large number of population movements have provided conditions for the spread of schistosomiasis and caused the continuation of this ancient disease. It is estimated that there are 6.5438+0.54 million patients in China, and thousands of cases of acute schistosomiasis occur every year, which is particularly harmful to children. Every year, the economic loss caused by schistosomiasis is incalculable. At present, there are still uncontrolled endemic areas in China, most of which are seriously prevalent lakes and swamps and remote mountainous areas with complex environment. Different epidemic areas have different situations and different targets, so the prevention and control countermeasures should be different. Therefore, schistosomiasis control should be based on local conditions, comprehensive management and scientific prevention. Since the founding of the People's Republic of China, the Party and * * * have been very concerned about the health of people in epidemic areas, organized large-scale schistosomiasis prevention and research, and have gone through decades of hardships. Before 1984, the purpose of schistosomiasis control was to block its spread, with the focus on eliminating vector snails. Some people think that the eradication of snails will lose the basis of transmission. After repeated, the effect is not ideal. 1984, due to the advent of new safe and effective drugs, who put forward a new prevention and control strategy, and used disease control to replace the past transmission interruption to feed the incidence of schistosomiasis. This strategy is feasible and effective. In addition, health education should be strengthened to let people know that their actions are closely related to the spread and prevention of schistosomiasis. The new prevention and control strategy takes large-scale and repeated chemotherapy as the main prevention and control measures, combined with safe water supply and improved sanitation facilities, and local snail control is carried out in conditional areas, which reduces the infection rate and infection degree in many areas. At present, the epidemic trend of schistosomiasis in China is that the epidemic situation in the basic control area and the monitoring area is still stable, and the resurgence of the epidemic situation in the uncontrolled area is basically contained and begins to decline. The strategy of schistosomiasis control has changed from comprehensive snail control to chemotherapy combined with snail control in susceptible areas. There is still a lot of work to be done to finally control and eliminate schistosomiasis, and the task is quite arduous. There are still some theoretical and technical problems that need to be further studied and solved.

2. Knowledge of schistosomiasis prevention

1. What is schistosomiasis? Any trematode parasitic in vertebrate blood vessels is called schistosomiasis.

Vertebrates refer to mammals such as humans and mammals (cattle, sheep, horses, pigs, dogs, cats, rats, etc.). ). There are many kinds of Schistosoma japonicum, among which 19 is related to human diseases.

Among them, Schistosoma japonicum, Schistosoma aegypti, Schistosoma Mekong, Schistosoma japonicum and Schistosoma hominis are the five species that cause schistosomiasis in people and animals. Schistosomiasis japonica is prevalent in China.

2. Where is schistosomiasis endemic? Schistosoma japonicum is highly pathogenic and widely distributed, including Japan, China, the Philippines and Indonesia. According to the anatomical analysis of ancient corpses unearthed in the Western Han Dynasty, it is confirmed that schistosomiasis japonica existed in China as early as 2000 years ago.

In China, it is mainly distributed in the Yangtze River basin and its southern provinces such as Hunan, Hubei, Jiangxi, Anhui, Jiangsu, Sichuan and Yunnan, but schistosomiasis is not prevalent in these areas, and some counties in various provinces are endemic areas. 3. What harm does schistosomiasis do to the body? Schistosomiasis is the main parasitic disease that seriously harms the health of our people.

It has a history of more than 2000 years since the discovery of schistosomiasis patients in ancient corpses of the Western Han Dynasty. Before liberation, many people died of schistosomiasis, and some villages were destroyed by schistosomiasis.

Patients with schistosomiasis may have no symptoms in the early stage, and may also have symptoms such as abdominal pain, diarrhea, bloody stool and fatigue. However, people generally don't pay attention to it. If it is not checked and treated in time, it will be repeatedly infected for a long time and gradually form chronic advanced schistosomiasis. Children suffering from schistosomiasis will affect their growth and development. They are short, mentally retarded and look like little old men. Women suffering from schistosomiasis have irregular menstruation, which affects their fertility and lacks fun in life; If it develops into advanced schistosomiasis, there will be abdominal ascites, hepatosplenomegaly, bulging belly and skinny bones, and some will vomit blood, which will seriously affect labor production and life, and it is impossible to get rich through labor. The harmfulness of schistosomiasis is the "five lives" that affect life, production, life, growth and fertility.

The life history of Schistosoma japonicum The development and reproduction of Schistosoma japonicum includes five stages: adult, egg, cercaria, cercaria and larva. Adult Schistosoma japonicum is parasitic in mesenteric vein of human or mammal, and some eggs are excreted with feces, hatched in water, and then drilled into snails to develop into cercaria.

When cercaria meets human or mammal, it invades its skin to form larvae, and then moves to mesenteric vein to parasitize and develop into adults. 5. What is epidemic water? Epidemic water refers to Schistosoma japonicum cercariae in ditches, fields and ponds in schistosomiasis endemic areas.

If people and animals come into contact with epidemic diseases, they will be invaded by cercariae, which will lead to schistosomiasis. 6. How is schistosomiasis spread? When people and animals come into contact with water containing Schistosoma cercariae, cercariae will quickly enter people and animals, and after about 37 days, it will develop into adult Schistosoma japonicum, parasitic in mesenteric blood vessels, and feed on blood to maintain life.

Female insects lay eggs in the blood vessels of mesenteric veins. Eggs contain metacercariae, and each female lays about 1000 eggs every day. These eggs are so small that they can only be seen with a microscope.

Eggs will release toxins and affect health; Eggs flow to the intestinal wall with blood flow, which can break through the intestinal wall and enter the intestinal cavity, and be discharged with stool. Feces containing schistosome eggs pollute the water source. When the water temperature is about 25℃, after about 4 hours, the miracidium in the egg breaks out of its shell and swims rapidly in the water. When they meet snails, they will quickly get into snails and breed in snails, forming a large number of cercariae.

Oncomelania snails with cercaria contact with water, and cercaria constantly escapes into the water. People and animals are infected by contact with cercaria in water, thus getting schistosomiasis. In this way, schistosomiasis circulates repeatedly, constantly endangering people's lives and health.

Seven, what are the main ways of human infection with schistosomiasis? There are two main ways of infection: one is productive infection. Such as farm work, seedling raising, transplanting, harvesting, irrigation, flood control and drainage, fishing, shrimp catching, mowing, etc.

The second is life-related infection. For example, washing clothes, washing vegetables, swimming, washing hands and feet in water infected with schistosomiasis.

8. What is a snail? Oncomelania hupensis the only intermediate host of schistosomiasis. This is an hermaphrodite amphibious snail.

The shape is conical, the length is generally not more than 1cm, and the width is generally not more than 4 mm The surface of the snail shell has longitudinal edges, generally 6-9 spirals, which are mainly distributed in the range of 1m above and below the waterline of beaches and ditches (mainly small agricultural ditches). Oncomelania hupensis mainly distributed near the water inlet and ridge of paddy field.

Nine, how to prevent schistosomiasis? The prevention and treatment of schistosomiasis is the first, followed by treatment. Prevention is to find ways to prevent schistosomiasis infection and prevent schistosomiasis in people and animals; Treatment is to treat people or livestock who have already suffered from schistosomiasis.

Avoid contact with water containing Schistosoma cercariae. During the epidemic season of schistosomiasis, people and animals should not wash clothes in rivers, ponds, ditches and ponds with snails, and primary and secondary school students should pay special attention not to play and bathe in these places.

If you have to work in these snail environments, you should take certain protective measures, such as wearing rubber boots, gloves or applying anti-mite cream on your body to avoid skin contact with water. Actively eliminate snails.

Killing snails is the most fundamental measure to prevent schistosomiasis infection. Without snails, schistosomiasis would not spread. Kill Oncomelania hupensis, one is drug killing; Second, combined with the basic construction of farmland water conservancy, new ditches are opened to fill old snails.

Actively check and treat schistosomiasis. To know whether you have schistosomiasis, you should actively accept schistosomiasis examination.

Primary and secondary school students are inspected at school, and adults are inspected by epidemic prevention personnel at home. At present, there are many inspection methods, such as fecal incubation test, intradermal test, indirect agglutination test and egg-circling test.

After the diagnosis of schistosomiasis, no matter whether there are symptoms or signs, it should be treated in time. At present, the drug used for treatment is called praziquantel, which has low toxicity, good curative effect and convenient administration.

X. What is acute schistosomiasis? Acute schistosomiasis often occurs in the first infected person who has no immunity to schistosomiasis infection, but a few patients with chronic or even advanced schistosomiasis can also occur after being infected with a large number of cercariae. Theoretically, any first-time infected person should show acute infection, but in clinic, only some infected people show acute infection.

3. Knowledge of schistosomiasis

Schistosoma japonicum is also called schistosomiasis. Schistosoma japonicum is parasitic on most vertebrates. Eggs enter the bladder through the vein wall and are excreted with urine. Larvae develop in intermediate host snails (mainly snails and snails). Mature larvae enter the final host through the skin or mouth. Schistosoma mansoni (Schistosoma mansoni) is found in large and small intestinal veins, mainly distributed in Africa and northern South America. Eggs are excreted with feces. The larvae enter the snail and then return to the final host through the skin. Schistosoma japonicum is mainly found in Chinese mainland, Japan, Taiwan Province Province, east indies and the Philippines. Besides humans, it also attacks other vertebrates, such as domestic animals and mice.

Schistosoma japonicum is different from other human parasitic trematodes in morphology, physiology and life history. For example, Schistosoma japonicum is hermaphrodite. Adults are parasitic in mesenteric vein or bladder vein plexus, and eggs are excreted by feces or urine, which varies with insect species. The tail of cercaria bifurcates and invades the host through the skin in water; There is no cercaria and cysticercosis in the life history. In this paper, Schistosoma japonicum is described in detail, and Schistosoma mansoni and Schistosoma japonicum are briefly introduced. Schistosoma japonicum is called "method" or "water method" in ancient literature, and it is mostly infected by skin contact with infected water with Schistosoma japonicum larvae. The Sui Dynasty and others said in "On the Etiology and Stages of Diseases Related to Water": "This is due to the accumulation of water and toxic gas, which gradually makes the abdomen bigger ... This is also called water-related stagnation. After infection, fever, aversion to cold, cough and chest pain can be seen at the initial stage; Long-term manifestations are hypochondriac mass and ascites swelling, and the consequences are more serious.

Be distributed

Schistosoma japonicum is distributed in 76 countries and regions in Asia, Africa and Latin America. It is estimated that 500-600 million people are threatened and the number of patients is 200 million (1990). There is only Schistosoma japonicum in China, which we usually call Schistosoma japonicum. The fact that the eggs of Schistosoma japonicum were seized from the ancient corpse of the Western Han Dynasty in Jiangling, Hubei Province shows that schistosomiasis has existed in China for at least 2 100 years.

Schistosomiasis is prevalent in 76 countries and regions around the world. Among them, Schistosoma japonicum is distributed in China, Japan, the Philippines and Indonesia in Asia. It was first discovered by the Japanese in Japan, so it was named Schistosoma japonicum. Schistosoma aegypti is distributed in Africa and West Asia. Schistosoma mansoni is distributed in Central and South America, the Middle East and Africa. Only schistosomiasis japonica is endemic in China. Schistosomiasis is prevalent in 74 countries and regions around the world, with a population of 600 million and 200 million people infected, and millions of people die of schistosomiasis every year.

Only Schistosoma japonicum is endemic in China. Schistosomiasis is the most important parasitic disease that harms people's health. According to statistics in the early days of liberation, about 1 0 million patients and10 million people were threatened by infection. Oncomelania hupensis covers an area of nearly 65.438+0.28 billion square meters, and the diseases are distributed in 654.38+03 provinces, municipalities and autonomous regions. In the severe epidemic areas, patients died one after another, leaving the building empty, ten rooms empty and the countryside barren, resulting in the tragic scene of "thousands of Ficus pumila people dying and thousands of households singing ghosts". After liberation, large-scale mass schistosomiasis control work was carried out and great achievements were made. By the end of 1970s, the number of patients had dropped to 2.5 million, and patients with advanced stage were rarely seen. The snail control area is more than 9 billion square meters, accounting for more than 80% of the snail control area, and there are many innovations in prevention and control research. The vast endemic areas of schistosomiasis have undergone fundamental changes. However, a long and arduous struggle and the efforts of more people are needed to achieve the goal of completely eliminating schistosomiasis.

cause of a disease

Schistosoma japonicum is parasitic on mesenteric veins of humans and mammals, and it is dioecious. Its development can be divided into seven stages: worm, egg, metacercaria, female metacercaria, metacercaria, cercaria and larva. Eggs enter the liver with blood flow or are excreted with feces. It takes several hours for eggs to hatch into miracidium in water. The miracidium burrows into the body of Oncomelania hupensis in water and develops into mother, daughter and cercaria. Cercaria escapes from snails into the water, and after encountering humans and mammals, it burrows into the skin to become a child worm, then enters the vein or lymphatic vessel and moves to the mesenteric vein until it develops into an adult, and then lays eggs. Schistosoma cercaria invades the human body and develops into an adult about 100 days.

Principles of treatment

Chronic schistosomiasis

Praziquantel should be taken 40mg/kg or 1 twice a day.

Acute schistosomiasis

Praziquantel 1.20 mg/kg (children1.40 mg/kg) for 6 days. Patients with serious illness can be given support and symptomatic treatment before pathogen treatment.

Advanced schistosomiasis

Mainly to eradicate pathogens, improve symptoms, control and prevent complications. Except for upper gastrointestinal bleeding, high ascites and hepatic coma, praziquantel with a total amount of 60mg/kg can be taken orally for 3-6 times within 1-2 days. The treatment of complications can be combined with traditional Chinese and western medicine, internal medicine and surgery.