Ten years of occurrence of human Leishmania viannia braziliensis (Lvb) infections in farms around Três Braços, Bahia-Brazil

Some years ago w e published observations on the epidem iology o f cutaneous leishmaniasis due to Leishmania viannia brasiliensis (Lvb) from our fiel area in Tres Bracos, Bahia, Brazil regarding the occurrence o f human infections using techniques already described4. W e now data o f a further five years observations. The total data for 15 farms under study is set out in the Table 1. We also crudely quantify three factors that may influence this epidemiology namely the degree o f forestation o f the region, the quantify o f cacao grown (the chief economy o f the region) and the use of insecticide (Benzene Hexachloride) to protect this crop against insect pests. Scrutinising the total number o f cases for the decade there appears to be an association between prevalence o f human Lvb infection and forestation as illustrated by farms 1 ,1 4 and 15. Seven farms have not indexed a case for three years. There appears to be no association with cacao growing or insecticide although the probable vector Lutzomyia whitmani is abundant in such plantations and the peridomicile3 6. It is possible that the surviving forest contains the original hitherto unidentified wild animal reservoir o f Lvb as has been previously suggested2. Although more than 1,000 wild animals have been trapped in the area w e have only recorded on Lvb in one rodent5. W e intend to augment our field research in an attempt to identify this unknown reservoir. Although w e have identified two domestic animal reservoirs in the area11, only a wild animal reservoir could be related to such an association o f forest with human disease.