Exoerythrocytic cycle

The intrinsic life cycle begins when a female mosquito takes a blood meal. At this time, sporozoites that have matured in the mosquito s salivary glands are inoculated into the blood stream. These sporozoites migrate to the liver where they infect hepato-cytes and progress from early trophozoites to mature schizonts. This process is referred to as the exoerythrocytic cycle. Schizonts in the liver contain thousands of merozoites that are able to infect... 

An anopheline mosquito inoculates plasmodium sporozoites to initiate human infection (Figure 52-1). Circulating sporozoites rapidly invade liver cells, and exoerythrocytic stage tissue schizonts mature in the liver. Merozoites are subsequently released from the liver and invade erythrocytes. Only erythrocytic parasites cause clinical illness. Repeated cycles of infection can lead to the infection of many erythrocytes and serious disease. Sexual stage gametocytes also develop in erythrocytes before being taken up by mosquitoes, where they develop into infective sporozoites. 

D) Primaquine acts primarily on exoerythrocytic stages of the malarial life cycle... 

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