Schistosomiasis , also known as snail fever and bilharzia , is a disease caused by a parasitic flatworm called schistosomes. The urinary or gut can be infected. Symptoms include abdominal pain, diarrhea, bloody stools, or blood in the urine. Those who have been infected for a long time may experience liver damage, kidney failure, infertility, or bladder cancer. In children, it can lead to poor growth and learning difficulties.
The disease is spread by contact with fresh water contaminated with parasites. This parasite is released from an infected freshwater snail. This disease is very common among children in developing countries because they are more likely to play in contaminated water. Other high-risk groups include farmers, fishermen, and people who use unsanitary water during their daily lives. It belongs to the worm infection group. Diagnosis is to find a parasitic egg in the urine or a person's stool. This can also be confirmed by looking for antibodies against diseases in the blood.
Methods to prevent illness include increasing access to clean water and reducing the number of snails. In areas where the disease is common, praziquantel drugs can be given once a year to the entire group. This is done to reduce the number of people infected and, consequently, the spread of the disease. Praziquantel is also a treatment recommended by the World Health Organization (WHO) for those who are known to be infected.
Schistosomiasis affects about 252 million people worldwide by 2015. An estimated 4,400 to 200,000 people die each year. The disease is most commonly found in Africa, as well as Asia and South America. About 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.
Video Schistosomiasis
Signs and symptoms
Many individuals do not experience symptoms. If symptoms appear, they usually take four to six weeks from the time of infection. The first symptom of this disease is probably the general feeling of illness. Within twelve hours of infection, a person may complain of tingling sensation or a mild rash, commonly referred to as "swimmer itching," due to irritation at the point of entry. Rashes that can develop can mimic scabies and other types of rashes. Other symptoms can occur two to ten weeks later and may include fever, pain, cough, diarrhea, chills or enlarged glands. These symptoms can also be attributed to avian schistosomiasis, which does not cause further symptoms in humans.
The manifestations of schistosom infection vary from time to time as sercaria, and then the adult worms and their eggs migrate through the body. If the egg migrates to the brain or spinal cord, seizures, paralysis, or inflammation of the spinal cord may occur.
Bowel Skistosomiasis
In the intestinal schistosomiasis, the egg becomes lodged in the intestinal wall and causes an immune system reaction called granulomatous reaction. This immune response can cause colonic obstruction and blood loss. Individuals who are infected may have what looks like a fat belly. Eggs can also be nesting in the liver, which causes high blood pressure through the liver, enlarged spleen, buildup of fluid in the abdomen, and potentially life-threatening dilatation or swollen areas in the esophagus or digestive tract that can rip and release a lot of blood. (esophageal varices). In rare cases, the central nervous system is affected. Individuals with chronic active schistosomiasis may not complain of typical symptoms.
Dermatitis
The first potential reaction is a rash, the papular itch produced from cutaneous penetrating the skin, often in one's first infection. Round bulbs are usually one to three centimeters. Because people living in affected areas are often repeatedly exposed, acute reactions are more common in travelers and migrants. The rash may occur between the first few hours and a week after exposure and lasts for several days. A more severe similar reaction is called the "swimmer swimmer" reaction can also be caused by the cetaceous of animal trematodes that often infect birds.
Katayama fever
Another primary condition, called Katayama fever, may also develop from infection with this worm, and it can be very difficult to recognize. Symptoms include fever, lethargy, pale bulge eruption with a severe rash (urticaria), enlarged liver and spleen, and bronchospasm.
Acute schistosomiasis (Katayama fever) can occur several weeks or months after the initial infection as a systemic reaction to schistosomula migration as they pass through the bloodstream through the lungs to the liver. Like the swimmer's itch, Katayama's fever is more often seen in people with their first infections such as migrants and tourists. However, it was seen in native Chinese infected with S. japonicum . Symptoms include:
- Dry cough with chest x-ray changes
- Fever
- Fatigue
- Muscle aches
- Malaise
- Abdominal pain
- Enlarged liver and spleen
Symptoms usually improve on their own but a small percentage of people have persistent weight loss, diarrhea, diffuse stomach pain and rash.
Chronic illness
In a long-term illness, adult worms lay eggs that can cause an inflammatory reaction. Eggs secrete proteolytic enzymes that help them migrate to the bladder and intestines to shed. Enzymes also cause an eosinophilic inflammatory reaction when the egg is trapped in tissue or embolization to the liver, spleen, lungs, or brain. Long-term manifestations depend on schistosome species as adult worms from different species migrate to different areas. Many infections are mildly symptomatic, with anemia and malnutrition common in endemic areas.
Genitourinary Disease
Worms from S. haematobium migrate to the veins around the bladder and ureter. It can cause blood in the urine 10 to 12 weeks after infection. Over time, fibrosis can cause urinary tract obstruction, hydronephrosis, and renal failure. Diagnosis of bladder cancer and death generally increases in the affected area, with attempts to control schistosomiasis in Egypt have led to a decrease in bladder cancer rates. The risk of bladder cancer appears to be very high in male smokers, probably due to chronic irritation of the bladder lining that allows it to be exposed to carcinogens from smoking.
In women, genitourinary diseases may also include genital lesions that can lead to increased rates of HIV transmission.
Gastrointestinal disease
Worms from S. mansoni and S. japonicum migrate to the blood vessels in the gastrointestinal tract and liver. Eggs on the intestinal wall can cause pain, blood in the stools, and diarrhea (especially in children). Severe illness can cause narrowing of the large intestine or rectum. Eggs also migrate to the liver leading to fibrosis in 4 to 8 percent of people with chronic infection, especially those with long-term serious infections.
Central nervous system
Central nervous system lesions are common. Cerebral granulomatous disease may be caused by an S. japonicum egg in the brain. Communities in China affected by S. japonicum have a seizure rate eight times higher than baseline. Similarly, granulomatous lesions of S. mansoni
Maps Schistosomiasis
Transmission
Infected people release the eggs Schistosoma into the water through their fecal matter or urine. After the larvae hatch from these eggs, the larvae infect a very specific freshwater species. For example, in S. haematobium and S. intercalatum it is a snail of the genus Bulinus , in S. mansoni it is Biomphalaria and in S. japonicum it is Oncomelania . The Schistosoma larvae undergo the next phase of their life cycle in this snail, spending their time proliferating and developing. After this step is complete, the parasite leaves the slug and enters the water column. Parasites can live in water for only 48 hours without a human host. Once the host has been found, the worm enters its blood vessels. For several weeks, the worm will remain inside the vessel, continuing its development into its adult phase. When maturity is achieved, marriage occurs and eggs are produced. Eggs enter the bladder/gut and are excreted through urine and feces and repetitive processes. If the egg is not excreted, the eggs can become embedded in body tissues and cause various problems such as immune reactions and organ damage.
Humans encounter Schistosoma's parasitic larvae when they enter contaminated water when bathing, playing, swimming, washing, fishing, or walking in the water.
Diagnosis
Identify eggs in stool
The diagnosis of infection is confirmed by the identification of eggs in the stool. Eggs from S. mansoni are about 140 x 60 m and have lateral spine. Diagnosis is enhanced through the use of the Kato-Katz technique, semi-quantitative stool inspection techniques. Other methods that can be used are enzyme-linked immunosorbent assay (ELISA), rainfall test, and immunoassay alkaline phosphatase.
Identification of microscopic eggs in stool or urine is the most practical method for diagnosis. A fecal 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 may present in stools in infection with all species of Schistosoma . Examination can be done on a simple test (1 to 2 mg of fecal matter). Because eggs can be passed intermittently or in small quantities, their detection will be enhanced by repeated examination or concentration procedures, or both. In addition, for field surveys and investigation purposes, egg output can be quantified using the Kato-Katz technique (20 to 50 mg of stool) or Ritchie techniques. Eggs can be found in the urine in infection with S. haematobium (recommended time for collection: between noon and 3 pm) and with S. japonicum . Quantification is possible by using filtration through a nuclear filter membrane of the standard volume of urine followed by the number of eggs on the membrane. A tissue biopsy (rectal biopsy for all species and bladder biopsy for S. Haematobium ) may show eggs when stool examination or urine is negative.
Antibody detection
Detection of antibodies can be useful for showing schistosome infection in people who have traveled to areas where schistosomiasis is common and in whom eggs can not be shown in fecal or urine specimens. The sensitivity and specificity of the test varies greatly among the many reported tests for the serological diagnosis of schistosomiasis and depends on both types of antigen preparations used (crude, purified, adult, egg, cercarial) and test procedures.
At the US Centers for Disease Control and Prevention (CDC), a combination of tests with purified adult worm antigen is used for antibody detection. All serum specimens were tested by FAST-ELISA using adult microsomal adult antigen S. mansoni . A positive reaction (more than 9 units/ml serum) showed an infection with the species Schistosoma . The susceptibility to S. mansoni infection was 99 percent, 95 percent for S. haematobium infection, and less than 50 percent for S. japonicum infection. The specificity of this examination to detect schistosome infection is 99 percent. Because test sensitivity with ELISA-FAST was reduced for species other than S. mansoni , immunoblots of species corresponding to the patient's travel history were also tested to confirm the detection of S. haematobium and S. japonicum infection. Immunoblots with adult microsomal antigen antigens are species-specific and thus positive reactions indicate which species are infecting. The presence of antibodies only shows schistosome infection at some time and can not be attributed to clinical status, worm load, egg production, or prognosis. Where a person has traveled can help determine which species of Schistosoma will be tested by immunoblot.
In 2005, a field evaluation of a new handheld microscope was conducted in Uganda for the diagnosis of bowel schistosomiasis by a team led by Russell Stothard of the London Museum of Natural History, working with the Schistosomiasis Control Initiative, London.
Prevention
Many countries seek to eradicate the disease. WHO promotes this effort. In some cases, urbanization, pollution, and destruction of snail habitats have consequently reduced exposure, with subsequent declines in new infections. Praziquantel drugs are used for prevention in high-risk populations living in areas where the disease is common.
CDC recommends avoiding drinking or contact with contaminated water in areas where schistosomiasis is common.
A review of 2014 found temporary evidence that increased access to clean water and sanitation reduced schistosome infections.
Snails, dams and shrimps
Over the years since the 1950s, many dams and irrigation schemes have been built, causing a large increase in water-induced infections from schistosomiasis. The detailed specifications listed in various United Nations documents since the 1950s can minimize this problem. Irrigation schemes can be designed to make it difficult for slugs to colonize water and reduce contact with local residents. Although guidance on how to design this scheme to minimize the spread of the disease has been published many years before, the designers are unaware of them. The dam appears to have reduced the large migratory shrimp population of Macrobrachium . After the construction of fourteen large dams, a greater increase of schistosomiasis takes place in the historical habitat of native prawns than in other areas. Furthermore, at the 1986 Diamen Dam on the Senegal River, restoring shrimp in the upper reaches of the dam reduces snail density and reinfection rates of human schistosomiasis.
Treatment
There are two medications available, praziquantel and oxamniquine, for the treatment of schistosomiasis. They are considered equivalent in relation to efficacy against S. mansoni and security. Because of the lower cost per treatment of praziquantel, and the lack of oxaminiquine efficacy against the urogenital form of disease caused by S. haematobium, praziquantel is generally considered the first choice for treatment. The goal of treatment is to cure the disease and prevent the acute evolution to the chronic form of the disease. All suspected cases of schistosomiasis should be treated regardless of labor because adult parasites can live on the host for years.
Schistosomiasis can be treated by taking by mouth a dose of praziquantel medicine each year.
WHO has developed guidelines for community care based on the impact of disease on children in villages where 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-aged children are treated.
- When fewer than 20 percent of children have symptoms, mass treatment is not implemented.
Other treatments may include a combination of praziquantel with metrifonate, artesunate, or mefloquine. A Cochrane review found temporary evidence that when used alone, metrifonate is as effective as praziquantel.
Another agent, mefloquine, which had previously been used to treat and prevent malaria, was recognized in 2008-2009 to be effective against Schistosoma .
Epidemiology
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 central Africa, respectively.
The disease is endemic in some 75 developing countries and mainly affects people living in rural agricultural and suburban areas.
Estimated infection
In 2010, about 238 million people were infected with schistosomiasis, 85 percent of whom lived in Africa. Previous estimates from 2006 have placed numbers on the 200 million people infected. In many of the affected areas, schistosomiasis infects most children under 14 years of age. An estimated 600 to 700 million people worldwide are at risk for this disease because they live in countries where the organism is common. In 2012, 249 million people need treatment to prevent illness. This is likely to make it the most common parasitic infection with second malaria and cause about 207 million cases by 2013.
S. haematobium , the infectious agent responsible for urogenital schistosomiasis, infects more than 112 million people annually in Sub-Saharan Africa alone. It is responsible for 32 million dysuria cases, 10 million cases of hydronephrosis, and 150,000 deaths from kidney failure each year, making it the most lethal schistosome S. haematobium in the world.
Death
Estimates of the number of deaths vary. Worldwide, the Global Burden of Disease Study released in 2010 estimates 12,000 direct deaths while WHO in 2014 estimates more than 200,000 deaths per year associated with schistosomiasis. Another 20 million have severe consequences from this disease. This is the most lethal of neglected tropical diseases.
History
Schistosomiasis is known as bilharzia or bilharziosis in many countries, after German physician Theodor Bilharz, who first described the cause of urinary schistosomiasis in 1851.
The first doctor to describe the entire cycle of disease was the Brazilian parasitologist PirajÃÆ'¡ da Silva in 1908. The earliest known infection case was discovered in 2014, belonging to a child who lived 6,200 years ago.
It was a common cause of death for the Egyptians in the Greco-Roman period.
By 2016 more than 200 million people need treatment but only 88 million people are actually treated for schistosomiasis.
Etymology
Schistosomiasis is named after the genus of the parasitic flat worm Schistosoma , whose name means 'separate body'. The name Bilharzia comes from Theodor Bilharz, a German pathologist working in Egypt in 1851 who first discovered this worm.
Society and culture
Endemic schistosomiasis in Egypt, exacerbated by dams and irrigation projects along the Nile. From the late 1950s to early 1980s, infected villagers were treated with repeated injections of emetic tartars. Epidemiological evidence suggests that this campaign has inadvertently contributed to the spread of hepatitis C through an unclean needle. Egypt has the highest rates of hepatitis C infection in the world, and rates of infection in different parts of the country are closely linked to the timing and intensity of anti-schistosomiasis campaigns. From ancient times until the early 20th century, the symptoms of schistosomiasis' blood in urine are seen as menstrual versions of men in Egypt and thus are seen as a transitional rite for boys.
Among human parasitic diseases, schistosomiasis ranks second behind malaria in terms of socio-economic and public health interests in the tropics and subtropics.
Research
Vaccines
Like other major parasitic diseases, there is ongoing research to develop a schistosomiasis vaccine that will prevent the parasite from completing its life cycle in humans.
In September 2014, Eurogentec Biologics developed a vaccine called "Bilhvax" against S. haematobium infection in partnership with INSERM and researchers from the Pasteur Institute. As of September 2016, no results of the Phase III trials completed in 2012 have been reported.
References
External links
- Schistosomiasis in Curlie (based on DMOZ)
- River of Hope - a documentary about the emergence of schistosomiasis along the Senegal river (video, 47 minutes)
- Schistosomiasis information for travelers from IAMAT (International Association for Medical Assistance to Travelers)
- Freitas, A. R. R.; Angerami, R. N. (2013). "Spinal Cord Schistosomiasis". In El Ridi, R. Parasitic Disease - Schistosomiasis . InTech. doi: 10.5772/55787. ISBNÃ, 978-953-51-0942-6 Ã,
Source of the article : Wikipedia
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