RESUMEN
BACKGROUND: Despite the identification of some environmental factors linked to the cutaneous leishmaniasis (CL) epidemic, little is known about the impact of environmental disturbances caused by human activities. We assessed the association between socioeconomic and demographic factors with the spatial structure of the CL epidemic in Colombia. METHODS: Using data from more than 65 000 CL cases collected across the entire country from publicly available sources, we conducted a spatial clustering analysis to identify high burden areas (clusters) of CL. Associations between CL clusters and socioeconomic variables were investigated. RESULTS: We identified seven statistically significant clusters of CL located across all Colombian biomes. Deforestation and livestock were statistically significantly associated with the spatial clustering of CL. Urbanization, time spent traveling to main cities and water bodies were other factors linked with the clustering of CL. CONCLUSIONS: This study found that human activities such as deforestation linked to agriculture, livestock production and mining activities are key drivers of the spatial distribution of the CL epidemic. The intensity of these human activities, which are projected to increase because of social and economic transformations in progress in Colombia, will potentially exacerbate the already growing CL epidemic in the country.
RESUMEN
The potato yellow vein disease, caused by the potato yellow vein virus (PYVV), is a limiting potato disease in northern South America. The virus can be transmitted either by the greenhouse whitefly (GWF), Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae), or through vegetative propagules, such as infected tubers. Recently, GWF populations have been spotlighted as one of the main drivers of PYVV re-emergence, and consequently, PYVV management has been predominantly directed toward vector control, which is heavily based on insecticide use. However, the drivers of the PYVV outbreaks as well as the contribution of GWF populations on the spread of PYVV among potato crops are still not completely understood. This study aims to assess the role of the GWF as a driver of the PYVV epidemic in the potato-producing areas in Colombia, one of the countries more severely affected by the PYVV epidemic, and whose geography allows the study of the spatial association between the vector and the disease epidemic across a wide altitude range. The geographical clusters where the PYVV epidemic is concentrated, as well as those of farms affected by the GWF were identified using a novel spatial epidemiology approach. The influence of altitude range on the association between PYVV and T. vaporarioum was also assessed. We found a relatively poor spatial association between PYVV epidemic and the presence of the GWF, especially at altitudes above 3,000 m above mean sea level. Furthermore, GWF populations could only explain a small fraction of the extent of the PYVV epidemic in Colombia. Movement of infected seed tubers might be the main mechanism of dispersion, and could be a key driver for the PYVV infection among potato crops. Agricultural policies focused on improving quality of seed tubers and their appropriate distribution could be the most efficient control intervention against PYVV dispersion.