Age infection curve:
Human populations in areas with endemic schistosomiasis show a characteristic relation between age and infection level. Infection typically rises rapidly during childhood, peaking at around 8 - 15 years of age and then declining with increasing age. The infection intensity is measured as egg output in faeces or urine.
A further phenomen has been observed in human schistosomiasis infections, which is called "peak shift". "Peak shift" describes the fact that the peak level of intensity is higher and occurs at a younger age in populations with a higher overall infection intensity when compared with areas of lower infection intensity.The peaks also become more convex at higher levels of overall population infection intensity