The spatial and temporal patterns of falciparum and vivax malaria in Perú: 1994–2006

Gerardo Chowell,F Ellis Mckenzie,Cesar V Munayco,Ananias A Escalante

doi:10.1186/1475-2875-8-142

Gerardo Chowell, F Ellis Mckenzie + Show 2 more

Open Access

https://doi.org/10.1186/1475-2875-8-142

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Abstract

BackgroundMalaria is the direct cause of approximately one million deaths worldwide each year, though it is both preventable and curable. Increasing the understanding of the transmission dynamics of falciparum and vivax malaria and their relationship could suggest improvements for malaria control efforts. Here the weekly number of malaria cases due to Plasmodium falciparum (1994–2006) and Plasmodium vivax (1999–2006) in Perú at different spatial scales in conjunction with associated demographic, geographic and climatological data are analysed.MethodsMalaria periodicity patterns were analysed through wavelet spectral analysis, studied patterns of persistence as a function of community size and assessed spatial heterogeneity via the Lorenz curve and the summary Gini index.ResultsWavelet time series analyses identified annual cycles in the incidence of both malaria species as the dominant pattern. However, significant spatial heterogeneity was observed across jungle, mountain and coastal regions with slightly higher levels of spatial heterogeneity for P. vivax than P. falciparum. While the incidence of P. falciparum has been declining in recent years across geographic regions, P. vivax incidence has remained relatively steady in jungle and mountain regions with a slight decline in coastal regions. Factors that may be contributing to this decline are discussed. The time series of both malaria species were significantly synchronized in coastal (ρ = 0.9, P < 0.0001) and jungle regions (ρ = 0.76, P < 0.0001) but not in mountain regions. Community size was significantly associated with malaria persistence due to both species in jungle regions, but not in coastal and mountain regions.ConclusionOverall, findings highlight the importance of highly refined spatial and temporal data on malaria incidence together with demographic and geographic information in improving the understanding of malaria persistence patterns associated with multiple malaria species in human populations, impact of interventions, detection of heterogeneity and generation of hypotheses.

Highlights

Malaria is the direct cause of approximately one million deaths worldwide each year, though it is both preventable and curable
While most of the attention has been devoted to P. falciparum in Africa, an important element in malaria elimination programs outside Africa is P. vivax, a major challenge given that it requires an extended treatment in order to eradicate hypnozoites
Results suggest a triennial pattern for the P. falciparum series during 1998–2003 and a strong biennial cycle for P. vivax during 2002–2004 (Figure 2)

Summary

Introduction

Malaria is the direct cause of approximately one million deaths worldwide each year, though it is both preventable and curable. A key element for malaria elimination programmes is a good understanding of the malaria transmission dynamics in time and space. This is especially important in areas with low and intermediate seasonal transmission, such as those found in South America. There are still a limited number of studies considering the joint dynamic of these two parasites, P. falciparum and P. vivax, in time and space. In this investigation, the temporal and spatial trends of these parasites in Perú are explored as an example of the complex dynamic of these parasites in areas with seasonal malaria outside Africa. P. vivax has replaced P. falciparum as the dominant species since 2000 [3]

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