Spatial and temporal village-level prevalence of Plasmodium infection and associated risk factors in two districts of Meghalaya, India

Anne Kessler,Aparup Das,Bandapkupar Mawkhlieng,Sandra Albert,Catherine Walton,Mark L Wilson,Steven A Sullivan,Badondor Shylla,Anna Maria Van Eijk,Rilynti Lyngdoh,Upasana Shyamsunder Singh,Jane M Carlton

doi:10.1186/s12936-021-03600-w

Abstract

BackgroundDespite declining incidence over the past decade, malaria remains an important health burden in India. This study aimed to assess the village-level temporal patterns of Plasmodium infection in two districts of the north-eastern state of Meghalaya and evaluate risk factors that might explain these patterns.MethodsPrimary Health Centre passive malaria case data from 2014 to 2018 were analysed to characterize village-specific annual incidence and temporal trends. Active malaria case detection was undertaken in 2018 and 2019 to detect Plasmodium infections using PCR. A questionnaire collected socio-demographic, environmental, and behavioural data, and households were spatially mapped via GPS. Adult mosquitoes were sampled at a subset of subjects' houses, and Anopheles were identified by PCR and sequencing. Risk factors for Plasmodium infection were evaluated using bivariate and multivariate logistic regression analysis, and spatial cluster analysis was undertaken.ResultsThe annual malaria incidence from PHC-based passive surveillance datasets in 2014–2018 was heterogenous but declining across villages in both districts. Active surveillance in 2018 enrolled 1468 individuals from 468 households (West Jaintia Hills) and 1274 individuals from 359 households (West Khasi Hills). Plasmodium falciparum prevalence per 100 people varied from 0 to 4.1% in the nine villages of West Jaintia Hills, and from 0 to 10.6% in the 12 villages of West Khasi Hills. Significant clustering of P. falciparum infections [observed = 11, expected = 2.15, Relative Risk (RR) = 12.65; p < 0.001] was observed in West Khasi Hills. A total of 13 Anopheles species were found at 53 houses in five villages, with Anopheles jeyporiensis being the most abundant. Risk of infection increased with presence of mosquitoes and electricity in the households [Odds Ratio (OR) = 1.19 and 1.11], respectively. Households with reported animals had reduced infection risk (OR = 0.91).ConclusionMalaria incidence during 2014–2018 declined in all study villages covered by the passive surveillance data, a period that includes the first widespread insecticide-treated net campaign. The survey data from 2018 revealed a significant association between Plasmodium infection and certain household characteristics. Since species of Plasmodium-competent mosquito vectors continue to be abundant, malaria resurgence remains a threat, and control efforts should continue.

Highlights

Despite declining incidence over the past decade, malaria remains an important health burden in India
While anti-malarial drug therapy could be responsible for the decline, the causality is not clear, as artemether-lumefantrine (AL) against Plasmodium falciparum was introduced in the northeastern states of India in 2013 and has not changed since [2, 3]
Trends in malaria incidence from Meghalaya state data 2014–2018 Analysis of government data obtained for West Jaintia Hills and West Khasi Hills indicated temporal patterns in malaria incidence that were similar across villages (Fig. 2)

Summary

Introduction

Despite declining incidence over the past decade, malaria remains an important health burden in India. In 2018, India (4%) was one of five countries that accounted for close to 50% of all malaria cases worldwide, along with Nigeria (25%), Democratic Republic of the Congo (11%), Mozambique (5%), and Uganda (4%) [1]. The regions of India with high malaria incidence have more recently been found in the east and northeast of the country, with six states contributing roughly three-quarters of cases [2]. In the seven northeastern states, malaria is generally declining [3], but continues to impede the equitable health improvement and socioeconomic development of the region. Among the Meghalaya districts endemic for malaria, the majority of recent cases have been observed in the Garo Hills, West Khasi Hills, and West Jaintia Hills [4]. The decline could be related to the > 941,000 long-lasting insecticidal nets (LLINs) distributed throughout the state for the first time in mid-2016 by the Meghalaya state malaria control programme

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