What is meant by the "life cycle" of a parasite? What importance does it have to those who take care of patients with parasitic diseases?

The life cycle of a parasite occurs in various forms in all living hosts. The parasites must infect more than one hosts to complete their life cycle. So it is very important to know how many hosts have these parasites taken over, because then they will know how much longer the parasite will survive and how to treat it.