The Buen Pastor cemetery in Trujillo, Venezuela: measuring dengue vector output from a public area

Abstract

As vector control of dengue typically targets individual households to eliminate breeding sites or control adult mosquitoes during epidemics, public spaces are frequently neglected. To investigate the importance of such places as sources of dengue vectors, a study of Aedes aegypti productivity in a cemetery in northern Venezuela, using standard entomological indices for assessing dengue vector infestations, was carried out in the wet season in May 2003. Containers were found on 72.8% of graves; 44% of the containers held water and in 46.9% of these we found A. aegypti larvae and/or pupae. The average density of Aedes-infested containers was 39 per hectare. There were no significant differences in infestation rates between container types (vases, planters or others) or materials (cement, plastic, glass, etc.). Containers with 1-5 l of water held the greatest proportion of the pupae found in the cemetery (46.7%); containers with <100 ml of water contained no pupae. The mean number of pupae produced in the cemetery was estimated at 4185 pupae/ha per 48 h and the daily output of potential vector mosquitoes from the entire cemetery was calculated at approximately 3000 females per day. These mosquitoes presumably left the cemetery to feed in the nearby communities, thus thwarting the environmental management and health education programmes that had reduced household dengue vector infestations. The study shows the importance of public places as sources of dengue vectors in urban areas, and the need to include such areas in vector control programmes.