Helminth-Induced Human Gastrointestinal Dysbiosis: a Systematic Review and Meta-Analysis Reveals Insights into Altered Taxon Diversity and Microbial Gradient Collapse

Abstract

The gut microbiome has established importance in regulating many aspects of human health, including nutrition and immunity. While many internal and environmental factors are known to influence the microbiome, less is known about the effects of intestinal helminth parasites (worms), which together affect one-sixth of the world's population.

Effects of helminths on the human immune response and the microbiome

“…A common feature observed from some cross-sectional studies is increased gut microbial diversity in helminth-infected individuals 133,138,142,[144][145][146]151,153,159 ; however, some other studies showed either reduced diversity 146 or no significant differences in microbial diversity in infected individuals 134,135,139,140,143,148,154 . A recent effort to conduct a meta-analysis suggested helminths that colonized the large intestine, i.e., T. trichiura and Enterobius vermicularis are more likely to increase microbial diversity and alter microbial composition 160 . While the bacteria associated with helminth infections varies between studies, some commonly reported organisms fall in the order Clostridiales 136,139,155 , order Bacteroidales 136,138,155 , family Paraprevotellaceae 144,151 , family Lachnospiracaea 140,153 , and Bacteroides enterotype 141,142 .…”

“…In addition, studies have focused on different parasites, based on the study population including T. trichiura 133,144,149,155,157 , A. lumbricoides 147 , S. haematobium 139,156 , S. mansoni 154 S. japonicum 134 , Strongyloides stercoralis 151 , Clonorchis sinensis 142 , Haplorchis taichui 146 , E. vermicularis 159 , or mixed infections 136,138,140,141,143,145,148,150,152,153,158 . Differences in lifecycle and physical location in the intestine would likely affect the gut bacterial interactions 160 . Analyzing the composition of mucosal bacteria may be more informative for helminths (e.g., A. lumbricoides and hookworm) living in the small intestine.…”

Worms and bugs of the gut: the search for diagnostic signatures using barcoding, and metagenomics–metabolomics

“…Over the last decade, evidence has emerged that infections by soil-transmitted and GI helminths are accompanied by profound qualitative and quantitative modifications in the composition of the faecal microbiome of their hosts, although, to date, studies have mainly focused on the host bacteriome [128][129][130], rather than the virome [131] or mycobiome [132]. Modifications of the bacterial composition of the host microbiome can be characterized using microbiota-targeting metabarcoding and/or metagenomic approaches.…”

Detangling the Crosstalk Between Ascaris, Trichuris and Gut Microbiota: What´s Next?

“…This study found that in the case of Trichuris infection there was a positive association with Treponema sp., Anaerovibrio sp., Rikenellaceae and multiple species of Prevotellaceae. The authors propose that changes in the Firmicutes/Bacteroidetes (Bacillota/Bacteroidota) ratio, which has been shown to be a biologically relevant ratio, are strongly related to the presence of helminths, causing a shift from Bacteroidetes (Bacteroidota) to Firmicutes (Bacillota) and Clostridia, suggesting that helminth-induced enterotyping may have implications for host health ( Whitman et al., 2018 ; Kupritz et al., 2021 ). Likewise, in general, helminth infections are associated with greater richness and abundance and this difference is even more tailored when co-infections between different helminths occur, thus highlighting that the interaction of helminths with the host has a great relevance in the changes that can be potentially associated with health and disease ( Kupritz et al., 2021 ).…”