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 urinatingLower abdominal painBlood in urine (especially in the last few drops)General wea
7、kness The most frequent symptoms of intestinal schistosomiasis include: FeverAbdominal painDiarrhoea with blood and mucus (slimy substance) in the stoolLoss of appetiteGeneral weaknessEnlargement of the liver and spleenHOW DO PEOPLE BECOME INFECTED WITH SCHISTOSOMIASIS?People become infected with sc
8、histosomiasis 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 for the
9、 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 to blood
10、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 then rele
11、ased 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.Intermediate snail
12、 hosts for schistosomesIntermediate snail host forintestinal schistosomiasisIntermediate snail host forurinary 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 the snail C
13、ercaria 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). Children can eit
14、her 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 pole used t
15、o 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 for intestin
16、al 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 a
17、t school. WHO SHOULD NOT BE TREATED? If children are already unwell for some other reason, e.g. with a fever, treatment should be delayed until they are feeling better. If girls are pregnant, treatment should not be given in the first three months of pregnancy. Children with chronic illness such as
18、sickle cell anaemia. Children under one year old.ARE THERE ANY SIDE EFFECTS?Praziquantel is very safe and most people do not experience any side effects, but a small minority report mild and short lived symptoms. These may include headache, fever, stomach ache, diarrhoea and vomiting. Side effects a
19、re most likely to occur in people with heavy infections. If side effects are serious or persist, children should be taken to a clinic. Children should be given a small portion of staple food before treatment, to help allay the development of any side effects.WHAT ARE THE BENEFITS OF TREATMENT?Schist
20、osomiasis can be a very serious condition and it is important that children are treated to avoid some of the consequences of infection described above. Children will generally feel better after treatment, and will have to spend less time away from school through ill health and will be able to concen
21、trate and work better when they are in school.HOW DO YOU PREVENT BECOMING INFECTED WITH SCHISTOSOMIASIS AND PASSING ON INFECTION TO OTHERS? Use proper latrines/toilets, not open spaces in the bush or near water. Do not urinate in or near water that could become contaminated. Avoid walking through water or swimming and bathing in rivers, streams, ponds or canals that may be infected.
