LIFE –CYCLE OF MALARIAL PARASTICE

LIFE –CYCLE of plasmodium is completed in two hosts man and female anopheles mosquito Man serves as primary host whereas mosquito serves as secondary host the parasite completes its life cycle in two main phases[ A] asexualcycle in man and [B] sexual cycle in mosquito

ASEXUAL CYCLE IN MAN – SCHIZ OGONY

A healthy person acquires infection when a female anopheles mosquito containing infective [SPOROZOITES]of the parasite its salivary glands bites him for sucking his blood schizogony comprises of the following phases

[1] PER-ERYTHROCYTIC PHASE

ONCE WITHIN THE HUMAN BLOODS THE SPOROZOITES circulate for about half an hour and then get into the liver to invade the hepatic cells after penetrating the hepatic cells each sporozoite grows for number of days and become a schizont it divides to from a large number of uninucleate CRYPOZOITAN these are liberated when the liver cell bursts the cryptozoites invade fresh liver cells and multiply producing enormous numbers of METACRYPTOZOITES this phase is referred to as per-erythrocytic phase

ERYTHROCYTIC PHASE

[the metacryptozoites after escaping into the blood stream invade the red blood corpuscles each becomes rounded and is salled TROPHOZOITEC when it grows in size the nucleus is pushed to one side into the peripheral cytoplasm it resemblies a signet ring and is referred to as signet ring stage the TROPHOZOITE ingests a large amount of cytoplasm of the R.B.C. THE blood haemogobin is broken down into its protein component which is used by the trophozoite it develops into an active amoebo;d trophozoite after active feeding become rounded grows in size and become a SCHIZONT it now undergoes schizogony and produces MEROZOITES with the rupture of                  R.B.C.the merozoites are liberated and blood complete into the blood plasma these invade fresh corpuscies to repae the cycle the time taken to complete one erythrocytic cycle depands upon the spectes of plasmodium

[3] POST –ERYTHROCYTICPHASE

some merozoites produced in erythrocytic phase reach the liver cells and undergo schizonic development this is known as post erythroccytic phase

[4] GAMOGONY

WHEN successful asexual multiplication is achieved the merozoites do not proceed further with the erythrocytic phase but after entering the R.B.C. increase in size to become gamocytic male microgamocytes amd female macrogamocytic the gamocytes do not divide .but remain within their host blood until they ingested by the vendor in which they continue their development