Geographical and environmental determinants of a Colombian population of the leishmaniasis disease vector Lutzomyia longiflocosa (Diptera: Pyschodidae).

摘要

Introduction: Lutzomyia longiflocosa are peridomestic sand flies that transmit Leishmania parasites in Colombia. This species of sand fly has been implicated in recent epidemics in the Huila, Norte de Santander, and Tolima provinces. Human trends of deforestation and urbanization have raised this species to the interest of public health officials. Previous research has suggested that L. longiflocosa populations behave in distinctive seasonal patterns. This study examined those seasonal patterns by recording the impact of environmental and geographical attributes of the collection sites. Materials and Methods: CDC light traps were set in the afternoon, allowed to collect all night, and retrieved the following morning. Geographical attributes of the sites were recorded. Environmental data were recorded both in the afternoon and in the morning at each site. Collected insects were anesthetized, sorted, and identified with a stereo microscope. All Lutzomyia specimens were retained. Gold standards were produced by microscopy and genetic analysis in the laboratory. Linear regression models were produced to explain the variations in sand fly populations. Results: Over the 28 days of collection, a total of 1,095 L. longiflocosa specimens were obtained. The gold standards show a high degree of accuracy in the field identification key. Over the same time, temperature and wind speed increased, while humidity decreased. The only consistently productive trapping sites were located at the edge of a forest with direct proximity to livestock pasture. On a trap specific level, increases in temperature and wind speed have a positive effect on the number of sand flies collected, while increasing humidity exerts a negative effect. The same results were noted in the day-specific model. Discussion: This study demonstrated the characteristic seasonality of L. longiflocosa sand flies. This study also noted that these sand flies exist in distinctive focal points along the edges of forests directly adjacent to livestock pasture. In many developing countries, livestock are kept in close proximity to human residences. This represents an increased risk for sand fly and human contact, especially during periods of hot, dry weather. This study suggests sequestering livestock away from human habitation in Leishmania endemic regions, utilizing temperature or humidity recordings to guide local-level interventions, and insecticide sprayings that target the distinctive ecological foci of L. longiflocosa populations.