Geospatial risk prediction of hookworm infection and intensity among school-aged children in Dak Lak province, Vietnam

TL;DR

This study uses geospatial modeling to predict hookworm infection risks in school-aged children in Vietnam, identifying high-risk areas for targeted deworming.

Contribution

The novel use of geospatial modeling with environmental and climatic data to predict hookworm infection and intensity in a specific region.

Findings

Most of Dak Lak province had a predicted hookworm risk of 10–15% pre- and post-intervention.

High-risk hotspots for hookworm infection were identified in southern and eastern parts of the province.

Moderate-and-heavy intensity Necator americanus infection risk was significantly reduced post-intervention.

Abstract

Hookworms remain problematic in Dak Lak province, Vietnam, despite a school preventive chemotherapy (PC) program since 2007. As hookworms depend on favourable ecological conditions, geospatial modelling incorporating environmental and climatic variables can predict high-risk areas for targeted interventions. This study provides geospatial risk predictions for hookworm infection and intensity among school-aged children in Dak Lak.

Hookworm infection status and intensity from 7,964 school-aged children from 64 schools collected in 2019–2020 during the Community Deworming for STH trial was combined with environmental and climatic data to develop risk prediction models for (i) overall hookworm infection and (ii) moderate-and-heavy intensity (MHI) Necator americanus infection. Environmental and climatic predictors for the multivariable generalised linear models were selected by identifying the model with the lowest Akaike Information Criterion. Semivariograms were examined for residual spatial autocorrelation, and if present, was accounted for using Matérn’s covariance. Regression coefficients were used to predict overall hookworm and MHI N. americanus infection risk across Dak Lak province pre- and post-intervention.

Temperature, precipitation, soil and vegetation variables were included in the hookworm model, while temperature and precipitation variables were included in the MHI N. americanus model. Most of Dak Lak had a predicted hookworm risk of 10–15% pre- and post-intervention, with high-risk hotspots in southern and eastern parts. Moderate-and-heavy intensity N. americanus infection risk pre-intervention was higher than 2% throughout the province and considerably reduced to small pockets in southeastern, central and northern areas post-intervention.

School-based PC should be delivered across Dak Lak at least annually, in keeping with World Health Organization recommendations. However, several hotspots have been identified that would benefit from increased frequency of school-based PC or community-wide mass drug administration.

This geospatial analysis incorporated georeferenced parasitological data from 7,964 school-aged children across 64 schools involved in a large clinical trial with open-source environmental and climatic data to develop spatial risk prediction models for overall hookworm infection and moderate-and-heavy intensity hookworm infection pre- and post-intervention (community-wide or school-based deworming) across Dak Lak province, Vietnam. Our risk prediction maps showed most of Dak Lak had a predicted hookworm risk of 10–15% pre- and post-intervention, with high-risk (>50% prevalence) hotspots in southern and eastern parts of the province. There were considerable portions of the province with a moderate-and-heavy intensity Necator americanus infection risk higher than 2% pre-intervention, which considerably reduced post-intervention. These maps inform the implementation of geographically targeted control strategies, particularly for high-risk hotspots that would benefit from community-wide deworming to optimise reduction in hookworm infection and burden.

Figures