Question

A person suffering from a disease caused by Plasmodium experiences recurring chills and fever at the time when

Answer 1

Plasmodium enters the bloodstream of humans through the bite of an infected female Anopheles mosquito. The infective stage is called sporozoites. Sporozoites travel to the hepatic cells through the bloodstream. In the liver cells (hepatic cells) sporozoites undergo asexual division (exo-erythrocytic schizogony) to produce merozoites. Merozoite released from the liver cells penetrates erythrocytes. Inside the erythrocytes, these merozoites enlarge and are termed trophozoites. The trophozoites undergo asexual reproduction to produce schizont, which eventually divides to produced merozoites which are released upon erythrocytes lysis.

Upon erythrocytes lysis, a toxic substance called hemozoin along with merozoites is released which is responsible for symptoms of high fever and chill. The released merozoites infect other erythrocytes and this cycle repeats after every 72 to 48 hours depending upon the species of Plasmodium involved.

Occasionally merozoites differentiate into microgametocytes and macrogametocytes. When these erythrocytes containing macro and microgametocytes are ingested by female Anopheles mosquitoes, these develop into female and male gametes. In the mosquito gut, erythrocytes lyse and gametes fused to form a diploid zygote called ookinete. Ookinete migrates to the mosquito gut wall and penetrates and forms an oocyst. Oocyst undergoes meiosis and forms sporozoites which migrate to the salivary gland of mosquitoes. When a mosquito feeds on another host it transfers sporozoites along with saliva.

Blood-stage development