PARAMETERS OF LEISHMANIA BRAZILIENSIS TRANSMISSION BY INDOOR LUTZOMYIA OVALLESI IN VENEZUELA

We developed a mathematical model of cutaneous leishmaniasis (CL) transmission predicting CL incidence based on field data of number of positive sand flies, new CL cases, and number of susceptible people. We estimated the following parameters: a CL incubation period of one month, the overall susceptibility (Phi = 0.793), the serologic force of infection (lambda(m) = 0.108 /person/year, SD = 0.014), the clinical force of infection (lambda(l)= 0.114/year), the proportion of infections that result in skin lesions (alpha = 1.056), and the instantaneous reversal rate of Montenegro skin test-positive (MST(+)) people to MST(-) (rho= 0.124/year, SD = 0.021). We also provide the first field estimate of the transmission efficiency (epsilon = 0.0045, SD = 0.0009). The model predictions conform well with the observed new cases except for some small departures in the peaks and in some depressions (D(max) = 0.1494, P < 0.2). We discuss possible sources of error of our estimate of epsilon, and compare our parameter estimates with those obtained in Peru.