Transmission dynamics of filariasis in Khurdha district of Orissa, India.

A three year longitudinal study was carried out to quantify the different parameters of filarial transmission in an endemic area of Orissa State, India. Parasitological surveys revealed mean microfilaria rate, microfilaria density and median microfilaria density (MFD-50) to be 9.41, 19.23 and 7.33, respectively. The per man hour density of the vector, Culex quinquefasciatus varied from 24.2 to 66.0 with a peak in January. Infection rate varied from 0.9 to 27.5%, while infectivity rate ranged between 0.0 and 15.2%. Infectivity rate showed high correlation with microfilaria rate and per man hour density of adult mosquito. The highest numbers of first stage larvae (L1), second stage larvae (L2) and third stage larvae (L3) per mosquito were found to be 25, 22 and 11, respectively. Average L3 load per infective mosquito ranged from 1.0 to 7.2. L3 load showed high correlation with microfilaria rate (r = 0.845, p < 0.01) while no correlation was seen with microfilaria density.