Schistosoma bomfordi
Schistosoma bovis
Schistosoma curassoni
Schistosoma datta
Schistosoma edwardiense
Schistosoma guineensis
Schistosoma haematobium
Schistosoma harinasutai
Schistosoma hippopotami
Schistosoma incognitum
Schistosoma indicum
Schistosoma intercalatum
Schistosoma japonicum
Schistosoma kisumuensis
Schistosoma leiperi
Schistosoma malayensis
Schistosoma mansoni
Schistosoma margrebowiei
Schistosoma mattheei
Schistosoma mekongi
Schistosoma ovuncatum
Schistosoma nasale
Schistosoma rodhaini
Schistosoma sinensium
Schistosoma spindale
Schistosoma turkestanicum
Schistosoma is a genus of trematodes, commonly known as blood flukes. They are parasitic flatworms responsible for a highly significant group of infections in humans termed schistosomiasis, which is considered by the World Health Organization as the second-most socioeconomically devastating parasitic disease (after malaria), with hundreds of millions infected worldwide.[1][2]
Adult flatworms parasitize blood capillaries of either the mesenteries or plexus of the bladder, depending on the infecting species. They are unique among trematodes and any other flatworms in that they are dioecious with distinct sexual dimorphism between male and female. Thousands of eggs are released and reach either the bladder or the intestine (according to the infecting species), and these are then excreted in urine or feces to fresh water. Larvae must then pass through an intermediate snail host, before the next larval stage of the parasite emerges that can infect a new mammalian host by directly penetrating the skin.
The origins of this genus remain unclear. For many years it was believed that this genus had an African origin, but DNA sequencing suggests that the species (S. edwardiense and S. hippopotami) that infect the hippo (Hippopotamus amphibius) could be basal. Since hippos were present in both Africa and Asia during the Cenozoic era, the genus might have originated as parasites of hippos.[3] The original hosts for the South East Asian species were probably rodents.[4]
Based on the phylogenetics of the host snails it seems likely that the genus evolved in Gondwana between 70 million years ago and 120 million years ago.[5]
The cattle, sheep, goat and cashmere goat parasite Orientobilharzia turkestanicum appears to be related to the African schistosomes.[6][7] This latter species has since been transferred to the genus Schistosoma.[8]