Malaria intensity in Colombia by regions and populations.

Alejandro Feged-Rivadeneira,Camilo Rivera,Felipe González-Casabianca,Andrés Ángel,Luzia Helena Carvalho

doi:10.1371/journal.pone.0203673

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.

Highlights

Malaria in Colombia has been studied from a variety of disciplines that describe disease patterns with dimensions such as the diversity of the vector [1, 2], characteristics of the parasite [3], social phenomena affecting disease transmission [4, 5], and physical phenomena such as climate, weather and land use, [6,7,8], just to name some of the most important
The municipalities: Policarpa and Cumbitirain Nariño, El Reten in Magdalena and Calima in Valle del Cauca appear to be a hidden cluster for this parasite, since they were not marked as epidemic when considering all malarial parasites
We find that epidemic and endemic characteristics coexist in infection by Plasmodium vivax and Plasmodium falciparum

Summary

Introduction

Malaria in Colombia has been studied from a variety of disciplines that describe disease patterns with dimensions such as the diversity of the vector [1, 2], characteristics of the parasite [3], social phenomena affecting disease transmission [4, 5], and physical phenomena such as climate, weather and land use, [6,7,8], just to name some of the most important. Studies suggest that annual entomological inoculation rates (commonly computed as the product of the daily human biting rate, the sporozoite rates from the caught mosquitoes, and the days per year [33]) in Ghana (100-1000), Kenya (10-60) and Gambia (less than 10) are associated to prevention of all cause childhood mortality rates by insecticide treated bed nets, with efficacy of 17%, 33%, and 63%, respectively [32] These results suggest that public health policies should vary according to malaria endemicity, since bed nets have been the linchpin of malaria prevention strategies since DDT was discontinued as a viable alternative. In locations where malaria is intense, the use of bed nets is less efficient to prevent the burden of the disease

Methods

Results

Conclusion