Influence of meteorological parameters on the clinical presentation of cutaneous leishmaniasis in French Guiana and on the efficacy of pentamidine treatment of the disease.

In French Guiana, marked seasonal fluctuations have been observed in the numbers of individuals who present with cutaneous leishmaniasis (CL). To investigate the seasonal trends further, the clinical characteristics and responses to treatment of 455 cases of CL, who presented over a 3-year period (1995-1998), were compared against data on the weather for the calendar month of presentation (month 0) and for the month before presentation (month-1). Several statistically significant associations were observed. The number of sunlight hours in month -1 was lower for the treatment successes than for the treatment failures [adjusted odds ratio (AOR) for successful treatment=0.28; 95% confidence interval (CI)=0.13-0.6; P=0.001] and for those with long incubation periods than for those with relatively short incubation periods (multiple-regression coefficient=-0.003; P=0.002). However, the radiation intensity for month-1 was higher for the treatment successes than for the treatment failures (AOR=2.1; CI=1.1-3.8; P=0.02). Relatively high numbers of hours of sunlight on month-1 were associated with relatively high numbers of parasites on the skin smears (AOR=1.03; CI=1.01-1.04; P<0.001). Relatively high numbers of hours of sunlight during month 0 were associated with lymphangitis (AOR=0.4; CI=0.19-0.8; P=0.01). These results indicate that meteorological parameters may influence the evolution of CL, at least in French Guiana.