Date of Award

January 2023

Document Type

Thesis

Degree Name

Master of Public Health (MPH)

Department

School of Public Health

First Advisor

Michael Cappello

Second Advisor

Debbie Humphries

Abstract

Abstract

Introduction: Hookworms are soil-transmitted helminths (STHs) that cause significant morbidity in high-risk populations, posing a global health concern in locations of rural poverty [1-5]. While there have been ventures by the World Health Organization to eliminate hookworms in Africa by 2030, there is variability in the effectiveness of current chemotherapy regimens. Studies have shown that benzimidazole anthelmintics have reduced effectiveness, and people living in endemic areas are quickly reinfected [6]. Critical gaps remain in understanding parasite-host interactions within communities, further challenging successful disease control. A study initiated in 2022 investigated the epidemiology of human hookworm infection in Beposo, Ghana. Ultimately, it is critical to focus research endeavors in high-risk regions, as infections in sub-Saharan Africa account for nearly 40% of global hookworm infections, leading to increased morbidity [7].

Objectives: This research aimed to provide insight into the host-parasite relationship and epidemiologic factors that mediate human hookworm infection in West Africa. Collected study data were used to determine correlations that might exist between behavioral and demographic factors and hookworm infection status.

Methods: A community-wide survey of 1,047 consented and enrolled subjects (age 3-100 years; 48% females) was implemented to capture baseline demographics, including household, behavioral, and socioeconomic characteristics. Using serum collected from Beposo study subjects, an ELISA assay was developed to quantify serum IgG antibody responses to larval protein extracts (LEX) or adult worm excretory/secretory proteins (ES) isolated from a field strain of N. americanus.

Results: The hookworm prevalence was 28.6% (285/996) as measured by Kato Katz (KK) fecal microscopy. When assessing baseline epidemiological factors, there was a statistically significant correlation between drinking water source and hookworm infection. Multivariable logistic regression analysis revealed that those who retrieved drinking water from a borehole were 2.42 times more likely to be hookworm infected compared to subjects who consumed water from a pipe, after adjusting for study variables (CI 1.49-3.92, p-value <0.001). ELISA assay results revealed a statistically significant correlation between antibody response and Kato Katz infection status. Receiver operating characteristic (ROC) curve analysis yielded an area under the curve (AUC) of 0.77 for the association between Kato-Katz results and anti-ES IgG levels (p-value <0.001).

Conclusion: This study provides a better understanding of hookworm epidemiology so that more effective targeted interventions can be implemented to eliminate infection in endemic regions. The ELISA data demonstrates the potential utility of this novel, low-cost serologic assay as a tool for monitoring the effectiveness of hookworm control programs in endemic populations.

Comments

This thesis is restricted to Yale network users only. It will be made publicly available on 05/10/2025

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