Current epidemiological evidence for predisposition to high or low intensity human helminth infection: a systematic review
File(s)
Published version
Author(s)
Wright, James E
Werkman, M
Dunn, julia
Anderson, roy
Type
Journal Article
Abstract
Background: The human helminth infections include ascariasis, trichuriasis, hookworm infections, schistosomiasis,
lymphatic filariasis (LF) and onchocerciasis. It is estimated that almost 2 billion people worldwide are infected with
helminths. Whilst the WHO treatment guidelines for helminth infections are mostly aimed at controlling morbidity,
there has been a recent shift with some countries moving towards goals of disease elimination through mass drug
administration, especially for LF and onchocerciasis. However, as prevalence is driven lower, treating entire populations
may no longer be the most efficient or cost-effective strategy. Instead, it may be beneficial to identify individuals or
demographic groups who are persistently infected, often termed as being “predisposed” to infection, and target
treatment at them.
Methods: The authors searched Embase, MEDLINE, Global Health, and Web of Science for all English language, humanbased
papers investigating predisposition to helminth infections published up to October 31st, 2017. The
varying definitions used to describe predisposition, and the statistical tests used to determine its presence, are summarised.
Evidence for predisposition is presented, stratified by helminth species, and risk factors for predisposition to infection are
identified and discussed.
Results: In total, 43 papers were identified, summarising results from 34 different studies in 23 countries. Consistent
evidence of predisposition to infection with certain species of human helminth was identified. Children were regularly
found to experience greater predisposition to Ascaris lumbricoides, Schistosoma mansoni and S. haematobium than adults.
Females were found to be more predisposed to A. lumbricoides infection than were males. Household clustering of
infection was identified for A. lumbricoides, T. trichiura and S. japonicum. Ascaris lumbricoides and T. trichiura also showed
evidence of familial predisposition. Whilst strong evidence for predisposition to hookworm infection was identified,
findings with regards to which groups were affected were considerably more varied than for other helminth species.
Conclusion: This review has found consistent evidence of predisposition to heavy (and light) infection for certain
human helminth species. However, further research is needed to identify reasons for the reported differences between
demographic groups. Molecular epidemiological methods associated with whole genome sequencing to determine
‘who infects whom’ may shed more light on the factors generating predisposition.
lymphatic filariasis (LF) and onchocerciasis. It is estimated that almost 2 billion people worldwide are infected with
helminths. Whilst the WHO treatment guidelines for helminth infections are mostly aimed at controlling morbidity,
there has been a recent shift with some countries moving towards goals of disease elimination through mass drug
administration, especially for LF and onchocerciasis. However, as prevalence is driven lower, treating entire populations
may no longer be the most efficient or cost-effective strategy. Instead, it may be beneficial to identify individuals or
demographic groups who are persistently infected, often termed as being “predisposed” to infection, and target
treatment at them.
Methods: The authors searched Embase, MEDLINE, Global Health, and Web of Science for all English language, humanbased
papers investigating predisposition to helminth infections published up to October 31st, 2017. The
varying definitions used to describe predisposition, and the statistical tests used to determine its presence, are summarised.
Evidence for predisposition is presented, stratified by helminth species, and risk factors for predisposition to infection are
identified and discussed.
Results: In total, 43 papers were identified, summarising results from 34 different studies in 23 countries. Consistent
evidence of predisposition to infection with certain species of human helminth was identified. Children were regularly
found to experience greater predisposition to Ascaris lumbricoides, Schistosoma mansoni and S. haematobium than adults.
Females were found to be more predisposed to A. lumbricoides infection than were males. Household clustering of
infection was identified for A. lumbricoides, T. trichiura and S. japonicum. Ascaris lumbricoides and T. trichiura also showed
evidence of familial predisposition. Whilst strong evidence for predisposition to hookworm infection was identified,
findings with regards to which groups were affected were considerably more varied than for other helminth species.
Conclusion: This review has found consistent evidence of predisposition to heavy (and light) infection for certain
human helminth species. However, further research is needed to identify reasons for the reported differences between
demographic groups. Molecular epidemiological methods associated with whole genome sequencing to determine
‘who infects whom’ may shed more light on the factors generating predisposition.
Date Issued
2018-01-31
Date Acceptance
2018-01-17
Citation
Parasites & Vectors, 2018, 11
ISSN
1756-3305
Publisher
BioMed Central
Journal / Book Title
Parasites & Vectors
Volume
11
Copyright Statement
© The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver
(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver
(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
License URL
Subjects
1108 Medical Microbiology
1117 Public Health And Health Services
Mycology & Parasitology
Tropical Medicine
Publication Status
Published
Article Number
65
Date Publish Online
2018-01-31