Asymptomatic Plasmodium falciparum malaria prevalence among adolescents and adults in Malawi, 2015\u20132016

Hillary M Topazian,Gerald Tegha,Michael Kayange,David Mwalilino,Michael Emch,Ruth Njiko,Jessie K Edwards,Jonathan J Juliano,Jennifer S Smith,Irving Hoffman,Sydney Puerto-Meredith,Steven R Meshnick,Alexis Mwanza,Austin Gumbo,Tisungane Mvalo,Audrey Pettifor,Bernard Mvula

doi:10.1038/s41598-020-75261-9

Abstract

Malaria remains a significant cause of morbidity and mortality in Malawi, with an estimated 18–19% prevalence of Plasmodium falciparum in children 2–10 years in 2015–2016. While children report the highest rates of clinical disease, adults are thought to be an important reservoir to sustained transmission due to persistent asymptomatic infection. The 2015–2016 Malawi Demographic and Health Survey was a nationally representative household survey which collected dried blood spots from 15,125 asymptomatic individuals ages 15–54 between October 2015 and February 2016. We performed quantitative polymerase chain reaction on 7,393 samples, detecting an overall P. falciparum prevalence of 31.1% (SE = 1.1). Most infections (55.6%) had parasitemias ≤ 10 parasites/µL. While 66.2% of individuals lived in a household that owned a bed net, only 36.6% reported sleeping under a long-lasting insecticide-treated net (LLIN) the previous night. Protective factors included urbanicity, greater wealth, higher education, and lower environmental temperatures. Living in a household with a bed net (prevalence difference 0.02, 95% CI − 0.02 to 0.05) and sleeping under an LLIN (0.01; − 0.02 to 0.04) were not protective against infection. Our findings demonstrate a higher parasite prevalence in adults than published estimates among children. Understanding the prevalence and distribution of asymptomatic infection is essential for targeted interventions.

Highlights

Malaria remains a significant cause of morbidity and mortality in Malawi, with an estimated 18–19% prevalence of Plasmodium falciparum in children 2–10 years in 2015–2016
While children report the highest proportion of clinical disease[2], adults are thought to be an important reservoir to sustained transmission due to persistent asymptomatic infection
Using dried blood spots collected from the 2015–2016 Malawi Demographic and Health Survey (2015–2016 MDHS), we conducted quantitative polymerase chain reaction (PCR) to detect parasitemia

Summary

Introduction

Malaria remains a significant cause of morbidity and mortality in Malawi, with an estimated 18–19% prevalence of Plasmodium falciparum in children 2–10 years in 2015–2016. The annual P. falciparum parasite rate was estimated to be 18–19% in children ages 2–10 years in Malawi in 2015–20166, little is known about the prevalence of adult asymptomatic P. falciparum infection. The objective of the current analysis is to characterize and identify changes in the prevalence of asymptomatic P. falciparum, due to demographic, environmental, and spatial risk factors in Malawian adolescents and adults ages 15–54 years. Molecular surveillance of P. falciparum in adults can be an important tool for Ministries of Health to supplement ongoing collection of clinical data through national health management information systems and periodic national household surveys of malaria prevalence among children

Methods

Results

Conclusion