training module for medical officers primary health centre - NVBDCP
training module for medical officers primary health centre - NVBDCP
training module for medical officers primary health centre - NVBDCP
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o 70% humidity is idealFactors related to gametocytes affecting transmission dynamics Density and viability in circulation determine disease transmission Higher gametocytaemia in <strong>primary</strong> attack Gametocytes appear simultaneously with asexual stages in P.vivax, and are viable <strong>for</strong> 2 ½ to 4days. In P.falciparum gametocytes appear 7 to 8 days later or more after asexual stages and areviable <strong>for</strong> a longer period. Higher gametocyte density in P.falciparum as compared to P.vivax and P.malariae at the samelevel of asexual parasitaemia.Incubation interval and seasonal variationIncubation interval is the total period of extrinsic and intrinsic cyclesP.vivax: 22 days; P.falciparum : 35 daysSeasonal variations occur in incubation interval in unstable malariaP.vivax peak appears early in transmission season.P.falciparum peak appears later transmission season may be extended.Higher gametocytaemia in P.falciparum; higher vector infectivity and more sporozoites.Vectorial factorsVector densityMan biting rateFrequency of blood mealTime and place of man - mosquito contactMan - cattle ratioFlight rangeVector’s susceptibility to infection9