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1、FACTS ABOUT SCHISTOSOMIASIS Schistosomiasis (or Bilharzia) is a disease that primarily affects rural communities, involved in agriculture or fishing. Schistosomiasis affects millions of people throughout the world, especially children. Schistosomiasis causes a number of problems, making children fee
2、l unwell and affecting their physical and mental development, as well as affecting school attendance and performance.THE SCHISTOSOMESThere are two types of schistosomiasis in Zambia, the urinary type, caused by Schistosoma haematobium and the intestinal type, caused by Schistosoma mansoni. Schistoso
3、mes are small parasitic worms (flukes) that live in blood vessels around the bladder (urinary type) or intestine (intestinal type). WHAT PROBLEMS DO THEY CAUSE?The problems caused by infection with Schistosomes come not from the adult worms themselves but from the eggs. Only about half the eggs prod
4、uced by the adult worms leave the body in the faeces (intestinal type) or urine (urinary type). The remaining eggs stay in the body where they may lodge in blood vessels causing inflammation, obstruction and damage. With chronic, repeated infection this can lead to damage of the liver, intestines, l
5、ungs, kidneys, bladder and other organs. Schistosomiasis can contribute to anaemia and in some areas urinary schistosomiasis is also associated with a high rate of cancer of the bladder. In children, chronic infection can also lead to growth retardation, absence from school and decreased school perf
6、ormance.WHAT ARE THE SYMPTOMS OF SCHISTOSOMIASIS?People with light infections of schistosomes may not notice any symptoms. With heavier infection, the most common symptoms of urinary schistosomiasis are:Pain on urinating Lower abdominal pain Blood in urine (especially in the last few drops) General
7、weakness The most frequent symptoms of intestinal schistosomiasis include: Fever Abdominal pain Diarrhoea with blood and mucus (slimy substance) in the stool Loss of appetite General weakness Enlargement of the liver and spleenHOW DO PEOPLE BECOME INFECTED WITH SCHISTOSOMIASIS?People become infected
8、 with schistosomiasis when they come into contact with water (e.g. wading, bathing or swimming in ponds, rivers or lakes) that has been contaminated with urine or faeces from a person infected with schistosomiasis. The water also needs to contain the fresh water snails that act as intermediate hosts
9、 for the schistosome parasites.Schistosome life cyclesHuman urinary and intestinal schistosomes have very similar life cycles. The adult worms live in blood vessels around the bladder (urinary type) or intestine (intestinal type). Some of the eggs penetrate the walls of the bladder (which may lead t
10、o blood in the urine) or intestine. From there they are passed out with the urine or faeces. If the urine or faeces end up in water, the eggs hatch into small active larvae (miracidia). These then infect suitable fresh water snails where they multiply inside the snails. A second type of larvae are t
11、hen released from the snails (cercaria). These larvae can penetrate the skin of a person if they are in the water, travelling through the body to the liver, where they go through further growth and development, and then on to the veins around the intestine or bladder where the adults stay.Intermedia
12、te snail hosts for schistosomesIntermediate snail host for intestinal schistosomiasisIntermediate snail host for urinary schistosomiasisEggs in urine or faeces enter water and hatch into larvae (miracidia) Miracidia enter intermediate host a suitable snail. A second type of larvae (cerceria) leave t
13、he snail Cercaria penetrate the exposed skin of a person in the water WHAT IS THE TREATMENT FOR SCHISTOSOMIASIS?Schistosomiasis can be safely and effectively treated with praziquantel. This is given to children in a dose that depends on their size (50mg of praziquantel per kg of body weight). Childr
14、en can either be weighed, to work out the correct dose, or more easily, their height can be measured instead. Height and weight are related, so height can be used instead of weight to calculate how many pills of praziquantel should be given. This is most simply done using a tablet pole, which is a p
15、ole used to measure the childrens height, which has been marked with the correct number of pills for each height so the correct number of pills for each child can be found by just standing them against the tablet pole. Praziquantel for schistosomiasis can be given safely together with albendazole fo
16、r intestinal geohelminth infections such as roundworm, whipworm and hookworm. Reinfection with schistosomiasis can occur, so treatment should be repeated after a year if children become infected again. Treatment can be through a doctor or health worker, or by teachers who have been trained to treat children at school. WHO SHOULD NOT BE TREATED?If children are already unwell for some other reason, e.g. with a f
