1. Vertebrate (human) requirements
(i) New host: Sporozoites of malaria parasite require human as new host.
(ii) Merozoite Formation: Merozoites are not formed without a vertebrate host. Therefore, a vertebrate host is required for merozoite formation.
(iii) Schizogony: Hepatic and erythrocytic schizogony of malaria parasites is accomplished in humans or vertebrates.
(iv) Easy availability: Humans are readily available as vertebrate hosts.
(v) Continuity of the species: Production of male and female gametophytes is necessary to maintain the continuity of the species. Gametophytes are produced in human blood. Therefore, vertebrates are essential to prevent species extinction.
2. Invertebrate host (meshki) requirement for sex cycle
(i) Sex cycle: Malaria parasite requires mosquito for sex cycle.
(ii) Carrier of sporozoites: After sexual reproduction, the mosquito carries the sporozoites.
(iii) Easy availability: As an invertebrate host, muskrats are readily available in the vicinity of settlements.
(iv) Nutrition: The sporozoites obtain nutrition from the body of the mosquito.
(v) Life span: The mosquito lives longer than the time required for the malaria parasite to complete its sexual cycle.