Epidemiological assessment of malaria transmission in an endemic area of East Pakistan and the significance of congenital immunity.

A longitudinal epidemiological study was carried out in a hyperendemic malarious area of East Pakistan. Transmission of malaria was observed with two peaks, one in the premonsoon period, the other in the pre-winter period. New infections occurred in 51.7% of the infants surveyed who were 2 months old or under when first examined: there were frequent superinfections. The maternal immunity passively transferred to the infants did not play a significant role in restricting the development of the asexual erythrocytic stage or that of gametocytes, as indicated by the fact that the average parasite density and the gametocyte counts were highest in the 0-2-month age group and declined with increasing age. Mosquitos were collected for identification and for dissection to determine parity, the sporozoite rate, the vectorial capacity, and other basic indices. An. minimus was the principal vector, but An. leucosphyrous was also found to be positive.