It is the cause of schistosomiasis japonica, a disease that still remains a significant health problem especially in lake and marshland regions. Schistosomiasis is an infection caused mainly by three schistosome species; Schistosoma mansoni, Schistosoma japonicum and Schistosoma haematobium. Historical accounts of Katayama disease dates back to the discovery of S. Japonicum in Japan in The disease was named after an area it was endemic to, Katayama district, Hiroshima, Japan.
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Women doing domestic chores in infested water, such as washing clothes, are also at risk and can develop female genital schistosomiasis. Inadequate hygiene and contact with infected water make children especially vulnerable to infection. Migration to urban areas and population movements are introducing the disease to new areas.
Increasing population size and the corresponding needs for power and water often result in development schemes, and environmental modifications facilitate transmission. At times, tourists present severe acute infection and unusual problems including paralysis. Urogenital schistosomiasis is also considered to be a risk factor for HIV infection, especially in women.
Intestinal schistosomiasis can result in abdominal pain, diarrhoea, and blood in the stool. Liver enlargement is common in advanced cases, and is frequently associated with an accumulation of fluid in the peritoneal cavity and hypertension of the abdominal blood vessels.
In such cases there may also be enlargement of the spleen. The classic sign of urogenital schistosomiasis is haematuria blood in urine. Fibrosis of the bladder and ureter, and kidney damage are sometimes diagnosed in advanced cases. Bladder cancer is another possible complication in the later stages. In women, urogenital schistosomiasis may present with genital lesions, vaginal bleeding, pain during sexual intercourse, and nodules in the vulva.
In men, urogenital schistosomiasis can induce pathology of the seminal vesicles, prostate, and other organs. This disease may also have other long-term irreversible consequences, including infertility. The economic and health effects of schistosomiasis are considerable and the disease disables more than it kills. In children, schistosomiasis can cause anaemia, stunting and a reduced ability to learn, although the effects are usually reversible with treatment. The number of deaths due to schistosomiasis is difficult to estimate because of hidden pathologies such as liver and kidney failure, bladder cancer and ectopic pregnancies due to female genital schistosomiasis.
In , WHO estimated the annual death rate at globally. This should have decreased considerably due to the impact of a scale-up in large-scale preventive chemotherapy campaigns over the past decade. Current estimated total number of individuals with morbidity and mortality due to Schistosomiasis Haematobium and S. Mansoni infection in Sub-Saharan Africa Diagnosis Schistosomiasis is diagnosed through the detection of parasite eggs in stool or urine specimens.
For urogenital schistosomiasis, a filtration technique using nylon, paper or polycarbonate filters is the standard diagnostic technique. Children with S. The eggs of intestinal schistosomiasis can be detected in faecal specimens through a technique using methylene blue-stained cellophane soaked in glycerin or glass slides, known as the Kato-Katz technique. For people living in non-endemic or low-transmission areas, serological and immunological tests may be useful in showing exposure to infection and the need for thorough examination, treatment and follow-up.
Prevention and control The control of schistosomiasis is based on large-scale treatment of at-risk population groups, access to safe water, improved sanitation, hygiene education, and snail control. The WHO strategy for schistosomiasis control focuses on reducing disease through periodic, targeted treatment with praziquantel through the large-scale treatment preventive chemotherapy of affected populations.
It involves regular treatment of all at-risk groups. In a few countries, where there is low transmission, the interruption of the transmission of the disease should be aimed for. Groups targeted for treatment are: School-aged children in endemic areas. Adults considered to be at risk in endemic areas, and people with occupations involving contact with infested water, such as fishermen, farmers, irrigation workers, and women whose domestic tasks bring them in contact with infested water.
Entire communities living in highly endemic areas. WHO also recommends treatment of preschool aged children. The frequency of treatment is determined by the prevalence of infection in school-age children. In high-transmission areas, treatment may have to be repeated every year for a number of years. Monitoring is essential to determine the impact of control interventions. The aim is to reduce disease morbidity and transmission: periodic treatment of at-risk populations will cure mild symptoms and prevent infected people from developing severe, late-stage chronic disease.
However, a major limitation to schistosomiasis control has been the limited availability of praziquantel. Data for show that Praziquantel is the recommended treatment against all forms of schistosomiasis. It is effective, safe, and low-cost. Even though re-infection may occur after treatment, the risk of developing severe disease is diminished and even reversed when treatment is initiated and repeated in childhood. In Burundi, Burkina Faso, Ghana, Niger, Rwanda, Sierra Leone, the United Republic of Tanzania, and Yemen, it has been possible to scale-up schistosomiasis treatment to the national level and have an impact on the disease in a few years.
An assessment of the status of transmission is required in several countries. Over the past 10 years, there has been scale-up of treatment campaigns in a number of sub-Saharan countries, where most of those at risk live.
Although medically diverse, neglected tropical diseases share features that allow them to persist in conditions of poverty, where they cluster and frequently overlap. WHO coordinates the strategy of preventive chemotherapy in consultation with collaborating centres and partners from academic and research institutions, the private sector, nongovernmental organizations, international development agencies, and other United Nations organizations.
WHO develops technical guidelines and tools for use by national control programmes. Working with partners and the private sector, WHO has advocated for increased access to praziquantel and resources for implementation. A significant amount of praziquantel, to treat more than million children of the school age per year, has been pledged by the private sector and development partners. Geneva, World Health Organization;
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