|Classification and external resources|
|Pronunciation||/, , /|
Schistosomiasis, also known as bilharzia, snail fever, and Katayama fever, is a disease caused by parasitic flatworms of the Schistosoma type. The urinary tract or the intestines may be infected. Signs and symptoms may include abdominal pain, diarrhea, bloody stool, or blood in the urine. In those who have been infected a long time, liver damage, kidney failure, infertility, or bladder cancer may occur. In children, it may cause poor growth and learning difficulty.
The disease is spread by contact with fresh water contaminated with the parasites. These parasites are released from infected freshwater snails. The disease is especially common among children in developing countries as they are more likely to play in contaminated water. Other high risk groups include farmers, fishermen, and people using unclean water during daily living. It belongs to the group of helminth infections. Diagnosis is by finding eggs of the parasite in a person's urine or stool. It can also be confirmed by finding antibodies against the disease in the blood.
Methods to prevent the disease include improving access to clean water and reducing the number of snails. In areas where the disease is common, the medication praziquantel may be given once a year to the entire group. This is done to decrease the number of people infected and, consequently, the spread of the disease. Praziquantel is also the treatment recommended by the World Health Organization (WHO) for those who are known to be infected.
Schistosomiasis affected almost 210 million people worldwide as of 2012. An estimated 12,000 to 200,000 people die from it each year. The disease is most commonly found in Africa, as well as Asia and South America. Around 700 million people, in more than 70 countries, live in areas where the disease is common. In tropical countries, schistosomiasis is second only to malaria among parasitic diseases with the greatest economic impact. Schistosomiasis is listed as a neglected tropical disease.
- 1 Signs and symptoms
- 2 Diagnosis
- 3 Prevention
- 4 Treatment
- 5 Epidemiology
- 6 History
- 7 Society and culture
- 8 Research
- 9 References
- 10 Further reading
- 11 External links
Signs and symptoms
The first potential reaction is an itchy, papular rash:432 that results from cercariae penetrating the skin, often in a person's first infection. The round bumps are usually one to three centimeters big. Because people living in affected areas have often been repeatedly exposed, acute reactions are more common in tourists and migrants. The rash can occurs between the first few hours and a week after exposure and lasts for several days. A similar, more severe reaction called "swimmer's itch" reaction can also be caused by cercariae from animal trematodes that often infect birds.
Acute schistosomiasis (Katayama fever) may occur weeks or months after the initial infection as a systemic reaction against migrating schistosomulae as they pass through the bloodstream through the lungs to the liver. Similarly to swimmer's itch, Katayama fever is more commonly seen in people with their first infection such as migrants and tourists. However it is seen in native residents of China infected with S. japonicum. Symptoms include:
The symptoms usually get better on their own but a small proportion of people have persistent weight loss, diarrhea, diffuse abdominal pain and rash.
In long established disease adult worms lay eggs that can cause inflammatory reactions. The eggs secrete proteolytic enzymes that help them migrate to the bladder and intestines to be shed. However the enzymes also cause an eosinophilic inflammatory reaction when eggs get trapped in tissues or embolize to the liver, spleen, lungs or brain. The long term manifestations are dependent on the species of schistosome as the adult worms of different species migrate to different areas. Many infections are mildly symptomatic, with anemia and malnutrition being common in endemic areas.
The worms of S. haematobium migrate to the veins around the bladder and ureters. This can lead to blood in the urine 10 to 12 weeks after infection. Over time, fibrosis can lead to obstruction of the urinary tract, hydronephrosis and kidney failure. Bladder cancer diagnosis and mortality are generally elevated in affected areas, and have efforts to control schistosomiasis in Egypt have led to decreases in the bladder cancer rate. The risk of bladder cancer appears to be especially high in male smokers, perhaps due to chronic irritation of the bladder lining allowing it to be exposed to carcinogens from smoking.
The worms of S. mansoni and S. japonicum migrate to the veins of the gastrointestinal tract and liver. Eggs in the gut wall can lead to pain, blood in the stool, and diarrhea (especially in children). Severe disease can lead to narrowing of the colon or rectum. Eggs also migrate to the liver leading to fibrosis in 4 to 8 percent of people with chronic infection, mainly those with long term heavy infection.
Central nervous system disease
Central nervous system lesions occur occasionally. Cerebral granulomatous disease may be caused by S. japonicum eggs in the brain. Communities in China affected by S. japonicum have been found to have rates of seizures eight times higher than baseline. Similarly, granulomatous lesions from S. mansoni and S. haematobium eggs in the spinal cord can lead to transverse myelitis with flaccid paraplegia. Eggs are thought to travel to the central nervous system via embolization.
Microscopic identification of eggs in stool or urine is the most practical method for diagnosis. Stool examination should be performed when infection with S. mansoni or S. japonicum is suspected, and urine examination should be performed if S. haematobium is suspected. Eggs can be present in the stool in infections with all Schistosoma species. The examination can be performed on a simple smear (1 to 2 mg of fecal material). Since eggs may be passed intermittently or in small amounts, their detection will be enhanced by repeated examinations and/or concentration procedures. In addition, for field surveys and investigational purposes, the egg output can be quantified by using the Kato-Katz technique (20 to 50 mg of fecal material) or the Ritchie technique. Eggs can be found in the urine in infections with S. haematobium (recommended time for collection: between noon and 3 PM) and with S. japonicum. Quantification is possible by using filtration through a nucleopore filter membrane of a standard volume of urine followed by egg counts on the membrane. Tissue biopsy (rectal biopsy for all species and biopsy of the bladder for S. haematobium) may demonstrate eggs when stool or urine examinations are negative.
Antibody detection can be useful to indicate schistosome infection in people who have traveled to areas were schistosomiasis is common and in whom eggs cannot be demonstrated in fecal or urine specimens. Test sensitivity and specificity vary widely among the many tests reported for the serologic diagnosis of schistosomiasis and are dependent on both the type of antigen preparations used (crude, purified, adult worm, egg, cercarial) and the test procedure.
At CDC, a combination of tests with purified adult worm antigens are used for antibody detection. All serum specimens are tested by FAST-ELISA using S. mansoni adult microsomal antigen (MAMA). A positive reaction (greater than 9 units/µl serum) indicates infection with Schistosoma species. Sensitivity for S. mansoni infection is 99 percent, 95 percent for S. haematobium infection, and less than 50 percent for S. japonicuminfection. Specificity of this assay for detecting schistosome infection is 99 percent. Because test sensitivity with the FAST-ELISA is reduced for species other than S. mansoni, immunoblots of the species appropriate to the patient's travel history are also tested to ensure detection of S. haematobium and S. japonicum infections. Immunoblots with adult worm microsomal antigens are species-specific and so a positive reaction indicates the infecting species. The presence of antibody is indicative only of schistosome infection at some time and cannot be correlated with clinical status, worm burden, egg production, or prognosis. Were a person has traveled can help determine what Schistosoma species to test for by immunoblot.
In 2005 a field evaluation of a novel handheld microscope was undertaken in Uganda for the diagnosis of intestinal schistosomiasis by a team led by Russell Stothard from the Natural History Museum of London, working with the Schistosomiasis Control Initiative, London.
Many countries are working towards eradicating the disease. The WHO is promoting these efforts. In some cases, urbanization, pollution, and consequent destruction of snail habitat have reduced exposure, with a subsequent decrease in new infections. Furthermore, the drug praziquantel is used for prevention in high-risk populations living in areas were the disease is common.
Prevention is best accomplished by eliminating the water-dwelling snails that are the natural reservoir of the disease.
For many years from the 1950s onwards, vast dams and irrigation schemes were constructed, causing a massive rise in water-borne infections from schistosomiasis. The detailed specifications laid out in various UN documents since the 1950s could have minimized this problem. Irrigation schemes can be designed to make it hard for the snails to colonize the water, and to reduce the contact with the local population.
While guidelines on how to design these schemes to minimise the spread of the disease had been published years before, but the designers were unaware of them.
Schistosomiasis is treatable by taking by mouth a single dose of the drug praziquantel annually.
The WHO has developed guidelines for community treatment based on the impact the disease has on children in villages in which it is common:
- When a village reports more than 50 percent of children have blood in their urine, everyone in the village receives treatment.
- When 20 to 50 percent of children have bloody urine, only school-age children are treated.
- When fewer than 20 percent of children have symptoms, mass treatment is not implemented.
Other possible treatments include a combination of praziquantel with metrifonate, artesunate, or mefloquine. A Cochrane review found tentative evidence that when used alone, metrifonate was as effective as praziquantel.
Another agent, mefloquine, which has previously been used to treat and prevent malaria, was recognised in 2008–2009 to be effective against schistosoma.
The disease is found in tropical countries in Africa, the Caribbean, eastern South America, Southeast Asia, and the Middle East. S. mansoni is found in parts of South America and the Caribbean, Africa, and the Middle East; S. haematobium in Africa and the Middle East; and S. japonicum in the Far East. S. mekongi and S. intercalatum are found locally in Southeast Asia and central West Africa, respectively.
In 2010, approximately 238 million people were infected with schistosomiasis, 85 percent of whom live in Africa. An earlier estimate from 2006 had put the figure at 200 million people infected. In many of the affected areas, schistosomiasis infects a large proportion of children under 14 years of age. An estimated 600 to 700 million people worldwide are at risk from the disease because they live in countries where the organism is common. In 2012, 249 million people were in need of treatment to prevent the disease. This likely makes it the most common parasitic infection with malaria second and causing about 207 million cases in 2013.
S. haematobium, the infectious agent responsible for urogenital schistosomiasis, infects over 112 million people annually in Sub-Saharan Africa alone. It is responsible for 32 million cases of dysuria, 10 million cases of hydronephrosis, and 150,000 deaths from renal failure annually, making S. haematobium the world’s deadliest schistosome.
Estimates regarding the number of deaths vary. Worldwide in 2010 the Global Burden of Disease estimated 12,000 direct deaths while the WHO estimates more than 200,000 people die related to schistosomiasis yearly. Another 20 million have severe consequences from the disease. It is the most deadly of the neglected tropical diseases.
The first physician who described the entire disease cycle was Brazilian parasitologist Pirajá da Silva in 1908. The first known case of infection was discovered in 2014, belonging to a child who lived 6,200 years ago.
Society and culture
Schistosomiasis is endemic in Egypt, exacerbated by the country's dam and irrigation projects along the Nile. From the late 1950s through the early 1980s, infected villagers were treated with repeated injections of tartar emetic. Epidemiological evidence suggests that this campaign unintentionally contributed to the spread of hepatitis C via unclean needles. Egypt has the world's highest hepatitis C infection rate, and the infection rates in various regions of the country closely track the timing and intensity of the anti-schistosomiasis campaign. From ancient times to the early 20th century, schistosomiasis' symptom of blood in the urine was seen as a male version of menstruation in Egypt and was thus viewed as a rite of passage for boys.
Schistosomiasis was mentioned in an episode of the television sitcom WKRP in Cincinnati. In the episode "Frog Story" from season 3, Dr. Johnny Fever becomes concerned that he may have schistosomiasis. Among human parasitic diseases, schistosomiasis ranks second behind malaria in terms of socio-economic and public health importance in tropical and subtropical areas.
As with other major parasitic diseases, there is ongoing and extensive research into developing a schistosomiasis vaccine that will prevent the parasite from completing its life cycle in humans. In 2009, Eurogentec Biologics developed a vaccine against bilharziosis in partnership with INSERM and researchers from the Pasteur Institute.
Mirazid, an Egyptian drug made from myrrh, was under investigation for oral treatment of the disease up until 2005. Because praziquantel was proven to be about eight times as effective as Mirazid, it was not recommended as a suitable agent to control schistosomiasis.
- "schistosomiasis - definition of schistosomiasis in English from the Oxford dictionary". OxfordDictionaries.com. Retrieved 2016-01-20.
- "schistosomiasis". Merriam-Webster Dictionary.
- "Schistosomiasis (bilharzia)". NHS Choices. 17 December 2011. Retrieved 15 March 2014.
- "Schistosomiasis". Patient.info. 2013. Retrieved June 2014.
- "Schistosomiasis Fact sheet N°115". World Health Organization. 3 February 2014. Retrieved 15 March 2014.
- "Chapter 3 Infectious Diseases Related To Travel". cdc.gov. 1 August 2013. Retrieved 30 November 2014.
- Fenwick, A (Mar 2012). "The global burden of neglected tropical diseases.". Public Health 126 (3): 233–6. doi:10.1016/j.puhe.2011.11.015. PMID 22325616.
- Lozano, R.; Naghavi, M.; Foreman, K.; Lim, S.; Shibuya, K.; Aboyans, V.; Abraham, J.; Adair, T.; et al. (15 December 2012). "Global and regional mortality from 235 causes of death for 20 age groups in 1990 and 2010: a systematic analysis for the Global Burden of Disease Study 2010". Lancet 380 (9859): 2095–128. doi:10.1016/S0140-6736(12)61728-0. PMID 23245604.
- Thétiot-Laurent, S. A.; Boissier, J.; Robert, A.; Meunier, B. (27 June 2013). "Schistosomiasis Chemotherapy". Angewandte Chemie (International ed. in English) 52 (31): 7936–56. doi:10.1002/anie.201208390. PMID 23813602.
- "Schistosomiasis A major public health problem". World Health Organization. Retrieved 15 March 2014.
- The Carter Center. "Schistosomiasis Control Program". Retrieved 17 July 2008.
- "Neglected Tropical Diseases". cdc.gov. 6 June 2011. Retrieved 28 November 2014.
- Gryseels, Bruno; Polman, Katja; Clerinx, Jan; Kestens, Luc. "Human schistosomiasis". The Lancet 368 (9541): 1106–1118. doi:10.1016/s0140-6736(06)69440-3.
- James, William D.; Berger, Timothy G.; et al. (2006). Andrews' Diseases of the Skin: clinical Dermatology. Saunders Elsevier. ISBN 0-7216-2921-0.
- "Diagnosis and management of schistosomiasis". BMJ. May 17, 2011. doi:10.1136/bmj.d2651.
- Bottieau, Emmanuel; Clerinx, Jan; Vega, Maria Rosario de; Enden, Erwin Van den; Colebunders, Robert; Esbroeck, Marjan Van; Vervoort, Tony; Gompel, Alfons Van; Ende, Jef Van den. "Imported Katayama fever: Clinical and biological features at presentation and during treatment". Journal of Infection 52 (5): 339–345. doi:10.1016/j.jinf.2005.07.022.
- Ross, Allen G.P.; Bartley, Paul B.; Sleigh, Adrian C.; Olds, G. Richard; Li, Yuesheng; Williams, Gail M.; McManus, Donald P. (2002-04-18). "Schistosomiasis". New England Journal of Medicine 346 (16): 1212–1220. doi:10.1056/NEJMra012396. ISSN 0028-4793. PMID 11961151.
- Ross, Allen G. P.; Sleigh, Adrian C.; Li, Yuesheng; Davis, George M.; Williams, Gail M.; Jiang, Zheng; Feng, Zheng; McManus, Donald P. (2001-04-01). "Schistosomiasis in the People's Republic of China: Prospects and Challenges for the 21st Century". Clinical Microbiology Reviews 14 (2): 270–295. doi:10.1128/CMR.14.2.270-295.2001. ISSN 0893-8512. PMC 88974. PMID 11292639.
- "Trematodes (Schistosomes and Liver, Intestinal, and Lung Flukes)". Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. pp. 3216–3226.e3. ISBN 0443068399.
- "Schistosomiasis". www.niaid.nih.gov. Retrieved 2016-02-07.
- Mostafa M. H., Sheweita S. A., O'Connor P. J., "Relationship between schistosomiasis and bladder cancer", Clinical Microbiolgy Reviews, 1999 Jan;12(1):97-111, Pubmed 9880476
- "Female genital schistosomiasis: a neglected risk factor for the transmission of HIV?". Trans R Soc Trop Med Hyg. March 1995. PMID 7778161.
- Freitas A. R., Oliveira A. C., Silva L. J. (July 2010). "Schistosomal myeloradiculopathy in a low-prevalence area: 27 cases (14 autochthonous) in Campinas, São Paulo, Brazil". Mem. Inst. Oswaldo Cruz 105 (4): 398–408. doi:10.1590/s0074-02762010000400009. PMID 20721482.
- This article incorporates public domain material from the Centers for Disease Control and Prevention document "Schistosomiasis Infection: Laboratory Diagnosis" by Global Health - Division of Parasitic Diseases and Malaria (retrieved on 5 January 2016). This article incorporates text from this source, which is in the public domain.
- Stothard, J. Russell; et al. (November 2005). "Field Evaluation of the Meade Readview Handheld Microscope for Diagnosis of Intestinal Schistosomiasis in Ugandan School Children". The American Journal of Tropical Medicine and Hygiene 73 (5): 949–955. PMID 16282310.
- WHO (2013) Schistosomiasis: Progress report 2001–2011, strategic plan 2012–2020. Geneva: World Health Organization.
- Grimes, JET; Croll, D.; Harrison, W. E.; Utzinger, J.; Freeman, M. C.; Templeton, M. R. (2014). "The Relationship between Water, Sanitation and Schistosomiasis: A Systematic Review and Meta-analysis". PLOS Neglected Tropical Diseases 8 (12): e3296. doi:10.1371/journal.pntd.0003296. ISSN 1935-2735.
- Charnock, Anne (7 August 1980). "Taking Bilharziasis out of the irrigation equation". New Civil Engineer.
Bilharzia caused by poor civil engineering design due to ignorance of cause and prevention
- The IRG Solution — hierarchical incompetence and how to overcome it. London: Souvenir Press. 1984. p. 88.
- The Carter Center. "How is Schistosomiasis Treated?". Archived from the original on 25 February 2008. Retrieved 17 July 2008.
- Kramer, C.V.; Zhang, F.; Sinclair, D.; Olliaro, P. L. (6 August 2014). "Drugs for treating urinary schistosomiasis.". The Cochrane Database of Systematic Reviews 8: CD000053. doi:10.1002/14651858.CD000053.pub3. PMID 25099517.
- Xiao SH (November 2013). "Mefloquine, a new type of compound against schistosomes and other helminthes in experimental studies". Parasitology Research 112 (11): 3723–40. doi:10.1007/s00436-013-3559-0. PMID 23979493.
- Oliveira, G.; Rodrigues N. B., Romanha, A. J., Bahia, D. (2004). "Genome and Genomics of Schistosomes". Canadian Journal of Zoology 82 (2): 375–90. doi:10.1139/Z03-220.
- "Neglected Tropical Diseases". cdc.gov. 6 June 2011. Retrieved 28 November 2014.
- Vos, T; Flaxman, A. D.; Naghavi, M.; Lozano, R.; Michaud, C.; Ezzati, M.; Shibuya, K.; Salomon, J. A.; et al. (15 December 2012). "Years lived with disability (YLDs) for 1160 sequelae of 289 diseases and injuries 1990–2010: a systematic analysis for the Global Burden of Disease Study 2010". Lancet 380 (9859): 2163–96. doi:10.1016/S0140-6736(12)61729-2. PMID 23245607.
- WHO (2006). Guidelines for the Safe Use of Wastewater, Excreta and Greywater, Volume 4 Excreta and Greywater Use in Agriculture. (third ed.). Geneva: World Health Organization. ISBN 9241546859.
- "Schistosomiasis". Fact sheet N°115. WHO Media Centre. February 2014. Retrieved 6 December 2014.
- "Malaria". Fact sheet N°94. WHO Media Centre. March 2014. Retrieved 6 December 2014.
- Luke F. Pennington and Michael H. Hsieh (2014) Immune Response to Parasitic Infections, Bentham e books, Vol 2, pp. 93-124, ISBN 978-1-60805-148-9
- Kheir M. M., Eltoum I. A., Saad A. M., Ali M. M., Baraka O. Z., Homeida M. M.; Eltoum; Saad; Ali; Baraka; Homeida (February 1999). "Mortality due to schistosomiasis mansoni: a field study in Sudan". The American Journal of Tropical Medicine and Hygiene 60 (2): 307–10. PMID 10072156.
- Jordan, Peter (1985). Schistosomiasis. Cambridge: Cambridge University Press. p. 1. ISBN 0-521-30312-5.
- Cheng, Maria (20 June 2014). "Ancient parasite egg found in 6,200-year-old child skeleton gives earliest evidence of a modern disease". National Post. Associated Press.
- "Proceedings of the 13h Annual History of Medicine Days", a medical historical paper from University of Calgary. March 2004.
- Strickland GT (May 2006). "Liver disease in Egypt: hepatitis C superseded schistosomiasis as a result of iatrogenic and biological factors". Hepatology 43 (5): 915–22. doi:10.1002/hep.21173. PMID 16628669.
- Kloos, Helmut; Rosalie David (2002). "The Paleoepidemiology of Schistosomiasis in Ancient Egypt" (PDF). Human Ecology Review 9 (1): 14–25.
By the early twentieth century, the Egyptian population was well aware of the widespread occurrence of haematuria to the point where the passing of blood by boys was considered as a normal and even necessary part of growing up, a form of male menstruation linked with male fertility (Girges 1934, 103).
- Rutherford, Patricia (2000). "The Diagnosis of Schistosomiasis in Modern and Ancient Tissues by Means of Immunocytochemistry". Chungara, Revista de Antropología Chilena 32 (1). ISSN 0717-7356.
The ancient Egyptians also wrote of boys becoming men when blood was seen in their urine, as this was likened to the young female's first menstruation (Despommier et al. 1995). Also archaeological evidence such as wall reliefs, hieroglyphs and papyri all confirm that their lifestyle encompassed activities such as bathing, fishing and playing in the Nile, and this combined with bad sanitation habits, would make almost everyone susceptible to this infection.
- "Water-related Diseases". World Health Organization. Retrieved 29 November 2015.
- "BILHVAX — A vaccine against Bilharziose, A world first!". 20 April 2009.
- "300.000 morts évitées grâce au vaccin liégeois!". 20 April 2009.
- "Eurogentec, la société de biotechnologie située au Sart Tilman, produit et produira le vaccin contre la bilharziose.". 22 April 2009.
- See, for example, Soliman O. E.; et al. (December 2004). "Evaluation of myrrh (Mirazid) therapy in fascioliasis and intestinal schistosomiasis in children: immunological and parasitological study". Journal of the Egyptian Society of Parasitology 34 (3): 941–66. PMID 15587320.
- Botros, S.; Sayed, H.; El-Dusoki, H.; Sabry, H.; Rabie, I.; El-Ghannam, M.; Hassanein, M.; El-Wahab, Y. A.; Engels, D (February 2005). "Efficacy of mirazid in comparison with praziquantel in Egyptian Schistosoma mansoni-infected school children and households". The American Journal of Tropical Medicine and Hygiene 72 (2): 119–23. PMID 15741544.
|Wikimedia Commons has media related to Schistosoma.|
- Schistosomiasis at DMOZ
- UNHCO site on Schistosomiasis
- River of Hope — documentary about the rise of schistosomiasis along the Senegal river (video, 47 mins)
- Schistosomiasis information for travellers from IAMAT (International Association for Medical Assistance to Travellers)