The disease is most commonly found in Africa, 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. Signs and symptoms
Many individuals do not experience symptoms. If symptoms do appear, they usually take 4–6 weeks from the time of infection. The first symptom of the disease may be a general feeling of illness. Within 12 hours of infection, an individual may complain of a tingling sensation or light rash, commonly referred to as "swimmers itch", due to irritation at the point of entrance. The rash that may develop can mimic scabies and other types of rashes. Other symptoms can occur 2–10 weeks later and can include fever, aching, a cough, diarrhea, chills, or gland enlargement. These symptoms can also be related to avian schistosomiasis, which does not cause any further symptoms in humans.The manifestations of schistosomal infection vary over time as the cercariae, and later adult worms and their eggs, migrate through the body. If eggs migrate to the brain or spinal cord, seizures, paralysis, or spinal-cord inflammation are possible. Acute Infection
Manifestation of acute infection from schistosoma include cercarial dermatitis (hours to days) and acute schistosomiasis (2–8 weeks). Cercarial dermatitis
The first potential reaction is an itchy, maculopapular rash that results from cercariae penetrating the skin within the first 12 hours to days of cercarial skin penetration.
Mefloquine, which has previously been used to treat and prevent malaria, was recognised in 2008–2009 to be effective against Schistosoma.Historically, antimony potassium tartrate remained the treatment of choice for schistosomiasis until the development of praziquantel in the 1980s.Post-treatment monitoring
Osteopontin (OPN)  is a promising tool for monitoring Praziquantel efficacy and post-treatment fibrosis regression as (OPN) expression is modulated by Schistosoma mansoni egg antigens and its levels correlate with severity of schistosomiasis fibrosis and portal hypertension in mice and humans. Praziquantel (PZQ) pharmacotherapy reduces systemic OPN levels and liver collagen content in mice. 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 West Africa, respectively.The disease is endemic in about 75 developing countries and mainly affects people living in rural agricultural and peri-urban areas. Infection estimates
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. As of the latest WHO record, 236.6 million people were infected in 2019. In many of the affected areas, schistosomiasis infects a large proportion of children under 14 years of age.