Additional burden of asymptomatic and sub-patent malaria infections during low transmission season in forested tribal villages in Chhattisgarh, India

Rajendra M Bhatt,Kamaraju Raghavendra,Kona Madhavinadha Prasad,Mehul Kumar Chourasia,Gyanendra Singh,Shrity Suman,Hemraj M Meshram,Vinita Dubey,Jayant K Meshram,Immo Kleinschmidt,Dipak Kumar Swain

doi:10.1186/s12936-017-1968-8

Rajendra M Bhatt, Kamaraju Raghavendra + Show 9 more

Open Access

https://doi.org/10.1186/s12936-017-1968-8

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Abstract

BackgroundThe burden of sub-patent malaria is difficult to recognize in low endemic areas due to limitation of diagnostic tools, and techniques. Polymerase chain reaction (PCR), a molecular based technique, is one of the key methods for detection of low parasite density infections. The study objective was to assess the additional burden of asymptomatic and sub-patent malaria infection among tribal populations inhabiting three endemic villages in Keshkal sub-district, Chhattisgarh, India. A cross-sectional survey was conducted in March–June 2016, during the low transmission season, to measure and compare prevalence of malaria infection using three diagnostics: rapid diagnostic test, microscopy and nested-PCR.ResultsOut of 437 individuals enrolled in the study, 103 (23.6%) were malaria positive by PCR and/or microscopy of whom 89.3% were Plasmodium falciparum cases, 77.7% were afebrile and 35.9% had sub-patent infections.ConclusionsA substantial number of asymptomatic and sub-patent malaria infections were identified in the survey. Hence, strategies for identifying and reducing the hidden burden of asymptomatic and sub-patent infections should focus on forest rural tribal areas using more sensitive molecular diagnostic methods to curtail malaria transmission.

Highlights

The burden of sub-patent malaria is difficult to recognize in low endemic areas due to limitation of diagnostic tools, and techniques
Strategies for identifying and reducing the hidden burden of asymptomatic and sub-patent infections should focus on forest rural tribal areas using more sensitive molecular diagnostic methods to curtail malaria transmission
This study has demonstrated that the diagnostic efficiency of rapid diagnostic tests (RDT)

Summary

Introduction

The burden of sub-patent malaria is difficult to recognize in low endemic areas due to limitation of diagnostic tools, and techniques. Polymerase chain reaction (PCR), a molecular based technique, is one of the key methods for detection of low parasite density infections. The study objective was to assess the additional burden of asymptomatic and sub-patent malaria infection among tribal populations inhabiting three endemic villages in Keshkal sub-district, Chhattisgarh, India. The intensification of intervention measures, such as long-lasting insecticidal nets (LLINs), indoor residual spraying (IRS) of insecticides, artemisinin-based combination therapy (ACT) and improved surveillance methods, have resulted in a 37% reduction in malaria incidence globally and a 60% reduction in the malaria mortality rate between 2000 and 2015. India reported a more than 50% reduction in malaria cases and mortality from 2001 to 2015 [3]. Chhattisgarh is one of the tribal-populated states (33%) in the country,

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