Complexities and Perplexities: A Critical Appraisal of the Evidence for Soil-Transmitted Helminth Infection-Related Morbidity

Abstract

Background: Soil-transmitted helminths (STH) have acute and chronic manifestations, and can result in lifetime morbidity. Disease burden is difficult to quantify, yet quantitative evidence is required to justify large-scale deworming programmes. A recent Cochrane systematic review, which influences Global Burden of Disease (GBD) estimates for STH, has again called into question the evidence for deworming benefit on morbidity due to STH. In this narrative review, we investigate in detail what the shortfalls in evidence are. Methodology/Principal Findings: We systematically reviewed recent literature that used direct measures to investigate morbidity from STH and we critically appraised systematic reviews, particularly the most recent Cochrane systematic review investigating deworming impact on morbidity. We included six systematic reviews and meta-analyses, 36 literature reviews, 44 experimental or observational studies, and five case series. We highlight where evidence is insufficient and where research needs to be directed to strengthen morbidity evidence, ideally to prove benefits of deworming. Conclusions/Significance: Overall, the Cochrane systematic review and recent studies indicate major shortfalls in evidence for direct morbidity. However, it is questionable whether the systematic review methodology should be applied to STH due to heterogeneity of the prevalence of different species in each setting. Urgent investment in studies powered to detect direct morbidity effects due to STH is required.

Genetic Markers of Benzimidazole Resistance among Human Hookworms (Necator americanus) in Kintampo North Municipality, Ghana

“…Soil-transmitted helminth infections are rarely fatal, but chronic infection in children is associated with anemia and stunting, as well as potential delays in cognitive development and school performance. 3,4 Approximately 500 million people worldwide are infected with hookworms, including roughly 120 million in sub-Saharan Africa. 1,2 Strategies for control of hookworms and other STHs rely on periodic deworming of groups at greatest risk of morbidity.…”

WASH for WORMS: A Cluster-Randomized Controlled Trial of the Impact of a Community Integrated Water, Sanitation, and Hygiene and Deworming Intervention on Soil-Transmitted Helminth Infections

“…3 Chronic and high-intensity STH infections have been associated with significant morbidity, including malnutrition, and in the case of hookworm infections, iron-deficiency anemia that may be associated with poor maternal and cognitive outcomes. 4 Present World Health Organization (WHO) guidelines advocate for large-scale regular deworming campaigns with anthelmintic drugs (albendazole or mebendazole) that are safe and highly effective against A. lumbricoides and moderately effective against hookworm infections. 5,6 Deworming campaigns for STH control have mainly targeted school-aged children because the adverse health effects of STH infection disproportionately affect children, and school-based delivery of anthelmintic drugs has operational advantages.…”

Disturbance in human gut microbiota networks by parasites and its implications in the incidence of depression

“…When star is next to number, it means the species is only present in NP or P; when the star is next to a name it is the same but for genus. lowest income in the country, the highest index of child and adult morbidity and mortality by intestinal infection (children's age from 0 to 8 years old 58,59 , which is the highest vulnerability and death risk age 60 ), and the lowest access to health services. These conditions were determined by last 10 years of statistical information obtained from National information system of access to health 59 .…”