training module for medical officers primary health centre - NVBDCP

Table 2.1: Differentiation of characteristics of P. vivax and P.falciparumP.vivaxP. falciparumExo-Erythrocytic Tissue Phase in LiverPre-erythrocytic stage (days) 6-8 5 ½ -7Pre-patent period (days) 11-13 9-10Incubation period (days) 14 (12-17) or up to 6-12 months 12 (9-14)Mean diameter of mature tissue schizont 45µ 60µNo of merozoites in tissue schizont 10,000 30,000Erythrocytic SchizogonyErythrocytic schizogony cycle(hours) 48 48Parasitaemia per µl (cmm) Average 20,000 20,000 to 150,000Parasitaemia per µl (cmm) Maximum 50,000 200,000Primary attack Mild to severe Severe in non-immuneFebrile paroxysm (hours) 8-12 16-36 or longerPeriod of recurrence Variable ShortRelapse + NilDuration of untreated infection (years) 1 ½ - 5 1 – 2Microscopic differentiationRBCSizeColourParasiteStages in peripheral bloodNo. of parasites in RBCSize of Ring to Size of RBCStipplingNo. of merozoites per RBCPigmentEnlargedPaleAll stagesSingle; seldom more1/3Schuffner’s dots12-24Coarse, aggregatedNormal or smallNormalRings and gametocytesSingle or multiple1/5Maurer’s dots12-30Solid group granulesSpread of malariaThe plasmodia spread from person to person by the bite of mosquitoes. This process is called thetransmission of the disease, and the mosquitoes are the vectors of malaria. However, not allmosquitoes can act as malaria vectors. It is only mosquitoes belonging to the genus Anopheles - andthat too the female of the species which can carry the parasite and infect. Male Anopheles mosquitoesonly feed on plant juices and nectar and cannot transmit malaria.Sexual Cycle in MosquitoThe mosquito cycle (sporogony) begins when gametocytes are ingested by the vector mosquito whilefeeding on an infected person. The male gametocytes, after reaching the stomach of the mosquito anddevelop into 4-8 filaments called “microgametes”. The female gametocyte undergoes maturation tobecome a “macrogamete”. The microgametes get attracted to the macrogamete, and one of the12