CUTANEOUS LEISHMANIASIS IN THE PERUVIAN ANDES - FACTORS ASSOCIATED WITH VARIABILITY IN CLINICAL SYMPTOMS, RESPONSE TO TREATMENT, AND PARASITE ISOLATION RATE

The severity of cutaneous leishmaniasis may be determined by host immu nity, parasite virulence, and host or vector behavior. We performed a multivariate analysis to identify the main causes of the variability i n clinical symptoms, response to treatment, and parasite isolation rat e among Peruvian patients. The effect of host immunity was demonstrate d first by the finding that secondary infections induced smaller lesio ns associated with a lower parasite isolation rate than did primary in fections and, second, by the finding of fewer lesions in older patient s. Phenotypic differences between parasite populations were suggested by the observation that the mean scar size and number varied between v illages: patients had more scars in villages where the transmission ra tes were higher. Human behavior probably determined the site of lesion s on the body, since most lesions in the cooler South were on the head , whereas in the North, lesions were equally frequent on the extremiti es, In addition, older patients, who were more likely infected through occupational exposure, had fewer head lesions. Geographic variation i n the pattern of exposure to sandflies indicates that uta control stra tegies should be region specific.