Malaria intensity in Colombia by regions and populations

Abstract

Determining the distribution of disease prevalence among heterogeneous populations at the national scale is fundamental for epidemiology and public health. Here, we use a combination of methods (spatial scan statistic, topological data analysis and epidemic profile) to study measurable differences in malaria intensity by regions and populations of Colombia. This study explores three main questions: What are the regions of Colombia where malaria is epidemic? What are the regions and populations in Colombia where malaria is endemic? What associations exist between epidemic outbreaks between regions in Colombia? Plasmodium falciparum is most prevalent in the Pacific Coast, some regions of the Amazon Basin, and some regions of the Magdalena Basin. Plasmodium vivax is the most prevalent parasite in Colombia, particularly in the Northern Amazon Basin, the Caribbean, and municipalities of Sucre, Antioquia and Cordoba. We find an acute peak of malarial infection at 25 years of age. Indigenous and Afrocolombian populations experience endemic malaria (with household transmission). We find that Plasmodium vivax decreased in the most important hotspots, often with moderate urbanization rate, and was re-introduced to locations with moderate but sustained deforestation. Infection by Plasmodium falciparum, on the other hand, steadily increased in incidence in locations where it was introduced in the 2009-2010 generalized epidemic. Our findings suggest that Colombia is entering an unstable transmission state, where rapid decreases in one location of the country are interconnected with rapid increases in other parts of the country.

Malaria in Gold Miners in the Guianas and the Amazon: Current Knowledge and Challenges

“…In Brazilian municipalities where mining is a central economic activity, malaria appeared as an occupational disease especially in young men [34]. In Colombia, 89.3% of malaria cases originated from the six regions with the highest gold mining activity [5,35]. In Peru, until 2015, health facilities located in areas of intense illegal gold mining (Madre de Dios region) reported 30 times more malaria cases than those in non-mining areas [13,36].…”

Identity-by-descent relatedness estimates with uncertainty characterise departure from isolation-by-distance betweenPlasmodium falciparumpopulations on the Colombian-Pacific coast

“…Spatial trends evaluated using a threshold-free approach are also consistent: they show a general increase in 1-Wasserstein distance with geographic distance between cities besides Buenaventura and Tumaco (Figure 3). The 1-Wasserstein distance can be interpreted as the effort required to transform a distribution of parasite samples from one city into a distribution of parasite samples from another [16]. The small 1-Wasserstein distance between Buenaventura and Tumaco is thus consistent with elevated gene flow between P. falciparum populations sampled from these cities.…”

“…We then calculate the 1-Wasserstein distance, which minimises the total cost of transporting w a to w b , where is the cost of transporting a single unit, using ( w a , w b , ). This amounts to treating parasite samples from different cities as draws from different distributions, where the 1-Wasserstein distance can be interpreted as the effort required to transform a distribution of parasite samples from one city into a distribution from another [16]. City pairs with smaller 1-Wasserstein distances are interpreted as having greater connectivity between the P. falciparum populations collected from them.…”

“…Malaria epidemiology in Colombia is associated with a multitude of ecological, evolutionary and social factors (Table A.1), including human migration due to deforestation, illegal crops, gold mining [16–20], and the mass emigration of people fleeing the humanitarian crisis in Venezuela [21–24]. Understanding the interplay between e.g.…”

“…Understanding the interplay between e.g. migration, parasite population connectivity and the spread of antimalarial resistance is critical [16,18]. In preparation for studies of resistance, Echeverry et al genotyped P. falciparum samples from four provinces on the Colombian-Pacific coast [11].…”