Where is schistosomiasis commonly found

Eggs from the three species of schistosoma that cause disease in humans. From left to right: Schistosoma mansoni, Schistosoma haemotobium, Schistosoma japonicum. Image credit: Imgbuddy. Children bathe in a lake contaminated with schistosome larvae in Zambia. Image credit: Wellcome Photo Library.

Biomphalaria snails, one of the species of freshwater snail that act as an intermediate host for schistosome larvae. Image credit: Oregon State University via Flickr. Illustration to show the life cycle of the schistosome parasite. Many cases diagnosed in the UK result from swimming in Lake Malawi. Travellers should avoid contact with fresh water rivers and lakes in risk areas where possible.

Schistosomiasis is diagnosed by testing urine or stool, and blood samples serology , screening should be carried out several weeks after exposure to fresh water. Overview Schistosomiasis, or bilharzia, is caused by worms termed flukes that have a complex life cycle involving freshwater snails. Risk areas An estimated 90 percent or more of those requiring treatment for schistosomiaasis are thought to live in Africa [4].

Figure 1: Distribution of schistosomiasis, worldwide Source: World Health Organization, Please check our Country Information pages for individual country recommendations. Risk for travellers Travellers are at risk of schistosomiasis if they wade in, swim or have other contact with fresh water in endemic areas. Transmission Schistosoma eggs are excreted in human faeces S.

Diagnosis and treatment Travel history is essential in identifying schistosomiasis as a possible diagnosis, and also which species is likely. Preventing schistosomiasis There is no vaccine available for schistosomiasis and no drug available which prevents infection. Resources King C H. Tropical Infectious Diseases. Elsevier, Philadelphia, 2: World Health Organization.

Schistosomiasis: number of people receiving preventive chemotherapy in Wkly Epidemiol Rec. Schistosomiasis, a major public health problem. Human Schistosomiasis. Lancet ;; Fact Sheet No Geneva, February, Infectious diseases among travellers and migrants in Europe, EuroTravNet Euro Surveill. Am J Trop Med Hyg ; 79; Schistsomiasis among travelers: New Aspects of an Old Disease. Emerg Infect Dis. Moore E, Doherty J.

Schistosomiasis among travellers returning from Malawi: a common occurrence. Q J Med ; Schistosome infection among river rafters on Omo River, Ethiopia. J Trav Med. European Centre for Disease Prevention and Control. Rapid Risk Assessment. Male and female adult worms copulate and reside in the mesenteric venules, the location of which varies by species with some exceptions. For instance, S. However, both species can occupy either location and are capable of moving between sites.

The females size ranges from 7—28 mm, depending on species deposit eggs in the small venules of the portal and perivesical systems. The eggs are moved progressively toward the lumen of the intestine S. Various animals such as cattle, dogs, cats, rodents, pigs, horses, and goats, serve as reservoirs for S.

Intermediate hosts are snails of the genera Biomphalaria, S. The only known intermediate host for S. Schistosoma mansoni is found primarily across sub-Saharan Africa and some South American countries Brazil, Venezuela, Suriname and the Caribbean, with sporadic reports in the Arabian Peninsula.

Despite its name, it has long been eliminated from Japan. The other, less common human-infecting species have relatively restricted geographic ranges. To receive email updates about this page, enter your email address: Email Address. What's this? Links with this icon indicate that you are leaving the CDC website. Linking to a non-federal website does not constitute an endorsement by CDC or any of its employees of the sponsors or the information and products presented on the website.

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