SPHK1 and parasitic infectious disease: To elucidate the levels of SphK-1 in all intra-erythrocyte stages of P. falciparum, culture at 5–6% parasitemia with highly synchronized parasites at ring stage (10–12 hpi) was incubated in complete medium for a period of 18 and 30 h, and the stages were monitored by counting.