<unk>  is at risk of endangerment in large part due to the introduction of invasive species into its native habitat. Since 1973, both S. mansoni and S. haematobium have been found in places that have been traditionally inhabited by<unk> . This is thought to be because of the increase in transportation accessibility and the increase in forestry jobs in these habitats. Male S. mansoni and S. haematobium will both take priority over<unk>  when it comes to mate selection, leading to a smaller proportion of female<unk>  available for mating. While crosses with S. mansoni give no viable offspring, the pairing with a male S. haematobium will result in a hybrid organism. Most hybrids will have a diluted genome that is more closely related to S. haematobium, helping to bring about a decline in<unk>  populations. The other obstacle restricting the parasite's population growth is its selective distribution. The cercariae are very particular over where they develop, needing small, forested areas with streams to infect their human host. There are only a few of these regions in Africa, and they decrease in size every day due to deforestation. Prevalence In 2009, there were an estimated 200 million human infections of schistosomiasis. In 1999, the noted number of<unk>  infections was 1.73 million. Distribution There are two major strains of<unk> , both living in forested areas of Africa. One strain lives in the Congo area, particularly Zaire, and the other strain lives in the Lower Guinea area, mainly in Cameroon. Cameroon is a place of scientific interest because it is where all three species of human schistosomes live. Most relevant research conducted on<unk>  was performed in, or around, the Loum area in Cameroon.
Schistosoma intercalatum
Schistosoma indicum
Schistosoma malayensis
Echinostoma revolutum
Schistosoma mekongi
Onchocerca volvulus
Hymenolepis diminuta
Toxocara malayasiensis