In children there is a negative impact in terms of growth, nutritional status and cognitive development. Chronic infection leads to diseases of the liver, kidneys and bladder. Occasionally, the nervous system is affected causing seizures, paralysis or spinal cord inflammation. Cause Schistosomiasis infection in humans, the definitive hosts, is caused by three main species of flatworm, namely Schistosoma haematobium , S. japonicum , and S. mansoni . In Asia, cattle and water buffalo can be important reservoir hosts.
Infection occurs when free-swimming larvae penetrate human skin.
The larvae develop in fresh-water snails. Humans are infected when they enter larvae-infested water for domestic, occupational and recreational purposes. After skin penetration, the larvae transform and are carried by the blood to the veins draining the intestines or the bladder where they mature, mate and produce eggs. Eggs cause damage to various tissues, particularly the bladder and liver. The reaction to the eggs in tissues causes inflammation and disease.