Micro-epidemiology and spatial heterogeneity of P. vivax parasitaemia in riverine communities of the Peruvian Amazon: A multilevel analysis

Abstract

Malaria has steadily increased in the Peruvian Amazon over the last five years. This study aimed to determine the parasite prevalence and micro-geographical heterogeneity of Plasmodium vivax parasitaemia in communities of the Peruvian Amazon. Four cross-sectional active case detection surveys were conducted between May and July 2015 in four riverine communities in Mazan district. Analysis of 2785 samples of 820 individuals nested within 154 households for Plasmodium parasitaemia was carried out using light microscopy and qPCR. The spatio-temporal distribution of Plasmodium parasitaemia, dominated by P. vivax, was shown to cluster at both household and community levels. Of enrolled individuals, 47% had at least one P. vivax parasitaemia and 10% P. falciparum, by qPCR, both of which were predominantly sub-microscopic and asymptomatic. Spatial analysis detected significant clustering in three communities. Our findings showed that communities at small-to-moderate spatial scales differed in P. vivax parasite prevalence, and multilevel Poisson regression models showed that such differences were influenced by factors such as age, education, and location of households within high-risk clusters, as well as factors linked to a local micro-geographic context, such as travel and occupation. Complex transmission patterns were found to be related to human mobility among communities in the same micro-basin.

Population structure across scales facilitates coexistence and spatial heterogeneity of antibiotic-resistant infections

“…We were able to identify specific covariates that contribute to resistance levels and to promoting coexistence with drug-sensitive strains. Similar to the use of "risk-mapping" to predict the distribution of vector-borne diseases based on environmental [46][47][48][49] and human [49][50][51][52][53] factors, these findings suggest that spatial risk-based assessment may be useful for the study of drug resistance. Surveillance on a finer scale will be needed to test these ideas on empirical data.…”

Measuring the Contribution of Mobility on Malaria Persistence

“…Risk factors for malaria have different levels of determination, from individual to household [8,9,10,11,12]. At the individual level, immunity, genetic background, nutrition, work activities, adherence to preventive practices, travel history, are important determinants of exposure and disease.…”

“…At the household level, type of construction, distance to mosquito breeding sites, source of household income, preventive habits and customs are important determinants [9,6]. At the eco-social (community) level, type of landscape, economic activities, human occupation and human mobility are important determinants [8,13,14].…”

Sistema ecológico da malária

“…At the lowest, or micro scale, there is increased anopheline vector abundance resulting from a range of disturbances in the ecosystem, and increased human exposure as a consequence of inadequate housing 68 . At the community scale, weak institutions, marginalized settlers, high rates of in and out-migration, and human mobility together ensure the proliferation of Plasmodium parasites 24,30 . The national scale is characterized by an unplanned development program of land occupation based on distribution of small land properties 30 .…”

“…Malaria in the Amazon is characterized by a low transmission landscape, interspersed with malaria hotspots, that are spatially and temporally variable 20,21 . In such a heterogeneous landscape, malaria is a persistent public health threat 1,[22][23][24] . It is also seasonal, and has been shown to be linked to rainfall, dry season length and/ or survival of the main malaria vector Nyssorhynchus darlingi (Root) [25][26][27] .…”