Measurement of IgG antibodies against Schistosoma is used as an adjunct in the diagnosis of schistosomiasis.
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Schistosoma is a genus of parasitic flatworms, also known as blood flukes, that can cause a disease called schistosomiasis in humans. Schistosomiasis is a major neglected tropical disease affecting millions of people in various parts of the world, particularly in tropical and subtropical regions.
There are several species of Schistosoma that can infect humans, with three major ones responsible for the majority of infections:
- Schistosoma mansoni
- Schistosoma haematobium
- Schistosoma japonicum
These species have a defined geographic distribution, with S. mansoni occurring throughout sub-Saharan Africa, the Middle East, and the Caribbean. S. haematobium is found in much of the African continent and the Middle East and S. japonicum is localized to China, Indonesia, and other Asian countries.
The life cycle of Schistosoma is complex and involves two hosts: a freshwater snail and a mammal (usually a human). Transmission occurs through contact with contaminated freshwater sources, such as rivers, lakes, and ponds, where infected snails are present. Activities like swimming, bathing, and farming in infested water can lead to infection.
- Eggs produced by adult female schistosomes are released in the host's urine or feces and enter freshwater.
- Inside the freshwater, the eggs hatch and release miracidia, which infect specific freshwater snail species.
- Inside the snail, the parasite undergoes several developmental stages, leading to the release of cercariae, a free-swimming larval form.
- Cercariae penetrate the skin of a human host who comes into contact with contaminated water.
- In the human host, the cercariae develop into schistosomula, then adult worms. The adult worms inhabit the veins surrounding various organs, such as the intestines (S. mansoni and S. japonicum) or the urinary tract (S. haematobium).
Schistosomiasis can lead to a range of symptoms and health problems, depending on the species of Schistosoma and the organs affected. Common symptoms may include fever, fatigue, abdominal pain, diarrhea, and blood in the urine (hematuria). Chronic schistosomiasis can result in severe health complications, including liver and spleen enlargement, bladder, and kidney damage, and, in some cases, an increased risk of bladder cancer (associated with S. haematobium).
Diagnosis of schistosomiasis can be made by the detection of eggs in fecal or urine samples as appropriate for each species. Antibody detection can be useful for patients who reside in nonendemic areas but have recently traveled to regions where Schistosoma species are found and in whom eggs cannot be identified in fecal or urine examinations.
