Bilharzia

Alternative Names: Schistosomiasis; Katayama fever; Swimmer’s itch; Blood fluke

Definition: Bilharzia is a disease caused by parasitic worms. Infection with Schistosoma mansoni, S. haematobium, and S. japonicum causes illness in humans. About 200 million people are infected worldwide.

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Although it has a low mortality rate, Bilharzia often is a chronic illness that can damage internal organs and, in children, impair growth and cognitive development. The urinary form of schistosomiasis is associated with increased risks for bladder cancer in adults. Schistosomiasis is the second most socioeconomically devastating parasitic disease after malaria.

This disease is most commonly found in Asia, Africa, and South America, especially in areas where the water contains numerous freshwater snails, which may carry the parasite.

The disease affects many people in developing countries, particularly children who may acquire the disease by swimming or playing in infected water.

Bilharzia is known as Schistosomiasis or bilharziosis in many countries, after Theodor Bilharz, who first described the cause of urinary schistosomiasis in 1851.

The first doctor who described the entire disease cycle was Pirajá da Silva in 1908.

It was a common cause of death for Ancient Egyptians in the Greco-Roman Period.

Signs and symptoms:
Above all, Bilharzia is a chronic disease. Many infections are subclinically symptomatic, with mild anemia and malnutrition being common in endemic areas. Acute schistosomiasis (Katayama’s fever) may occur weeks after the initial infection, especially by S. mansoni and S. japonicum.

Manifestations include:

*Abdominal pain

*Cough

*Diarrhea

*Eosinophilia — extremely high eosinophil granulocyte (white blood cell) count.

*Fever

*Fatigue

*Hepatosplenomegaly — the enlargement of both the liver and the spleen.

*Genital sores — lesions that increase vulnerability to HIV infection. Lesions caused by schistosomiasis may continue to be a problem after control of the schistosomiasis infection itself. Early treatment, especially of children, which is relatively inexpensive, prevents formation of the sores.

*Skin symptoms: At the start of infection, mild itching and a papular dermatitis of the feet and other parts after swimming in polluted streams containing cercariae.

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Occasionally central nervous system lesions occur: cerebral granulomatous disease may be caused by ectopic S. japonicum eggs in the brain, and granulomatous lesions around ectopic eggs in the spinal cord from S. mansoni and S. haematobium infections may result in a transverse myelitis with flaccid paraplegia.

Continuing infection may cause granulomatous reactions and fibrosis in the affected organs, which may result in manifestations that include:

*Colonic polyposis with bloody diarrhea (Schistosoma mansoni mostly);

*Portal hypertension with hematemesis and splenomegaly (S. mansoni, S. japonicum);

*Cystitis and ureteritis (S. haematobium) with hematuria, which can progress to bladder cancer;

*Pulmonary hypertension (S. mansoni, S. japonicum, more rarely S. haematobium);

*Glomerulonephritis; and central nervous system lesions.

Bladder cancer diagnosis and mortality are generally elevated in affected areas.

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Causes:
You get a schistosoma infection through contact with contaminated water. The parasite in its infective stages is called a cercaria. It swims freely in open bodies of water.

On contact with humans, the parasite burrows into the skin, matures into another stage (schistosomula), then migrates to the lungs and liver, where it matures into the adult form.

 

Life cycle of the parasitic agents responsible for causing    Bilharzia

The adult worm then migrates to its preferred body part, depending on its species. These areas include the bladder, rectum, intestines, liver, portal venous system (the veins that carry blood from the intestines to liver), spleen, and lungs.

Schistosomiasis is not usually seen in the United States. It is common in many tropical and subtropical areas worldwide.

Diagnosis:
Microscopic identification of eggs in stool or urine is the most practical method for diagnosis. The stool exam is the more common of the two. For the measurement of eggs in the feces of presenting patients the scientific unit used is eggs per gram (epg). 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 (such as the formalin-ethyl acetate technique). 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. japonicum and with S. intercalatum (recommended time for collection: between noon and 3 PM). Detection will be enhanced by centrifugation and examination of the sediment. Quantification is possible by using filtration through a nucleopore membrane of a standard volume of urine followed by egg counts on the membrane. Investigation of S. haematobium should also include a pelvic x-ray as bladder wall calcificaition is highly characteristic of chronic infection.

Recently a field evaluation of a novel handheld microscope was undertaken in Uganda for the diagnosis of intestinal schistosomiasis by a team led by Dr. Russell Stothard from the Natural History Museum of London, working with the Schistosomiasis Control Initiative, London.

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.

The eggs of S. haematobium are ellipsoidal with a terminal spine, S. mansoni eggs are also ellipsoidal but with a lateral spine, S. japonicum eggs are spheroidal with a small knob.

Antibody detection can be useful in both clinical management and for epidemiologic surveys.

Treatment:
Bilharzia  is readily treated using a single oral dose of the drug praziquantel annually. 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.

The World Health Organization has developed guidelines for community treatment of schistosomiasis based on the impact the disease has on children in endemic villages:

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 less than 20 percent of children have symptoms, mass treatment is not implemented.
The Bill & Melinda Gates Foundation has recently funded an operational research program—the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) to answer strategic questions about how to move forward with schistosomiasis control and elimination. The focus of SCORE is on development of tools and evaluation of strategies for use in mass drug administration campaigns.

Antimony has been used in the past to treat the disease. In low doses, this toxic metalloid bonds to sulfur atoms in enzymes used by the parasite and kills it without harming the host. This treatment is not referred to in present-day peer-review scholarship; praziquantel is universally used. Outside of the U.S., there is a drug available exclusively for treating Schistosoma mansoni (oxamniquine) and one exclusively for treating S.hematobium (metrifonate). While metrifonate has been discontinued for use by the British National Health Service, a Cochrane review found it equally effective in treating urinary schistosomiasis as the leading drug, praziquantel.

Mirazid, an Egyptian drug, was under investigation for oral treatment of the disease up until 2005. The efficacy of praziquantel was proven to be about 8 times than that of mirazid and therefore mirazid was not recommended as a suitable agent to control schistosomiasis.

Experiments have shown medicinal castor oil as an oral anti-penetration agent to prevent schistosomiasis and that praziquantel’s effectiveness depended upon the vehicle used to administer the drug (e.g., Cremophor).

Prognosis:
Treatment before significant damage or severe complications occur usually produces good results.

Possible Complications:
•Bladder cancer
•Chronic kidney failure
•Chronic liver damage and an enlarged spleen
•Colon (large intestine) inflammation with bloody diarrhea
•Kidney and bladder obstruction
•Pulmonary hypertension
•Repeated blood infections can occur, because bacteria can enter the bloodstream through an irritated colon
•Right-sided heart failure
•Seizures

Prevention:
*Avoid swimming or wading in freshwater when you are in countries in which schistosomiasis occurs. Swimming in the ocean and in chlorinated swimming pools is generally thought to be safe.

*Drink safe water. Because there is no way to make sure that water coming directly from canals, lakes, rivers, streams or springs is safe, you should either boil water for 1 minute or filter water before drinking it. Boiling water for at least 1 minute will kill any harmful parasites, bacteria, or viruses present. Iodine treatment alone WILL NOT GUARANTEE that water is safe and free of all parasites.

*Bath water should be heated for 5 minutes at 150°F. Water held in a storage tank for at least 48 hours should be safe for showering.

*Vigorous towel drying after an accidental, very brief water exposure may help to prevent the Schistosoma parasite from penetrating the skin. You should NOT rely on vigorous towel drying to prevent schistosomiasis.

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

Resources:
http://www.nlm.nih.gov/medlineplus/ency/article/001321.htm
http://www.bbc.co.uk/health/physical_health/conditions/bilharzia1.shtml
http://goafrica.about.com/od/healthandsafety/p/biharzia.htm
http://en.wikipedia.org/wiki/Schistosomiasis

http://asb.wchsgis.net/huge/cano_carlos/image_page_cano.htm

http://www.eoearth.org/article/Schistosomiasis

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