Risk profiling of hookworm infection and intensity in southern Lao People's Democratic Republic using Bayesian models.

Armelle Forrer,Youthanavanh Vonghachack,Kongsap Akkhavong,Peter Odermatt,Penelope Vounatsou,Jürg Utzinger,Somphou Sayasone,Dalouny Bouakhasith,Guo-Jing Yang

doi:10.1371/journal.pntd.0003486

Abstract

BackgroundAmong the common soil-transmitted helminth infections, hookworm causes the highest burden. Previous research in the southern part of Lao People’s Democratic Republic (Lao PDR) revealed high prevalence rates of hookworm infection. The purpose of this study was to predict the spatial distribution of hookworm infection and intensity, and to investigate risk factors in the Champasack province, southern Lao PDR.MethodologyA cross-sectional parasitological and questionnaire survey was conducted in 51 villages. Data on demography, socioeconomic status, water, sanitation, and behavior were combined with remotely sensed environmental data. Bayesian mixed effects logistic and negative binomial models were utilized to investigate risk factors and spatial distribution of hookworm infection and intensity, and to make predictions for non-surveyed locations.Principal FindingsA total of 3,371 individuals were examined with duplicate Kato-Katz thick smears and revealed a hookworm prevalence of 48.8%. Most infections (91.7%) were of light intensity (1-1,999 eggs/g of stool). Lower hookworm infection levels were associated with higher socioeconomic status. The lowest infection levels were found in preschool-aged children. Overall, females were at lower risk of infection, but women aged 50 years and above harbored the heaviest hookworm infection intensities. Hookworm was widespread in Champasack province with little evidence for spatial clustering. Infection risk was somewhat lower in the lowlands, mostly along the western bank of the Mekong River, while infection intensity was homogeneous across the Champasack province.Conclusions/SignificanceHookworm transmission seems to occur within, rather than between villages in Champasack province. We present spatial risk maps of hookworm infection and intensity, which suggest that control efforts should be intensified in the Champasack province, particularly in mountainous areas.

Highlights

Hookworm disease is caused by chronic infection with Ancylostoma duodenale or Necator americanus and is of considerable public health importance in low- and middle- income countries in the tropics and subtropics [1]
Hookworm infections are widespread in the Champasack province, with homogeneous infection intensity and somewhat lower infection risk west of the Mekong River, which offers higher living conditions
Hookworm control should be intensified in the Champasack province, in the mountainous areas

Summary

Introduction

Hookworm disease is caused by chronic infection with Ancylostoma duodenale or Necator americanus and is of considerable public health importance in low- and middle- income countries in the tropics and subtropics [1]. Chronic hookworm infection cause intestinal blood loss and may result in poor iron status and iron deficiency anemia, in children, women of reproductive age, and individuals with high worm loads [4,5,6]. Preventive chemotherapy—that is the periodic administration of albendazole or mebendazole to school-aged children and other high-risk groups—is the backbone of the global control against hookworm and other soil-transmitted helminth infections [7,8]. Among the common soil-transmitted helminth infections, hookworm causes the highest burden. Previous research in the southern part of Lao People’s Democratic Republic (Lao PDR) revealed high prevalence rates of hookworm infection. The purpose of this study was to predict the spatial distribution of hookworm infection and intensity, and to investigate risk factors in the Champasack province, southern Lao PDR

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