Related Experiment Video
Updated: Feb 20, 2026
Microbiota Analysis Using Two-step PCR and Next-generation 16S rRNA Gene Sequencing
Published on: October 15, 2019
Is the hygiene hypothesis relevant for the risk of multiple sclerosis?
M Wendel-Haga1,2, E G Celius2,3,4
1Department of Neurology, Telemark Hospital, Skien, Norway.
Abstract:
The hygiene hypothesis, suggesting that low exposure to pathogens early in life can increase the risk for immune-mediated diseases, has been proposed as an explanation for the increase in incidence of allergy and autoimmune diseases in industrialized countries during the last decades. Several aspects of the hygiene hypothesis have been related to MS. Already in 1966, the risk of MS was suggested to be higher in individuals with high hygienic standard during childhood. Further, an episode of infectious mononucleosis is an independent risk factor for MS and can be regarded as an indicator of low exposure to pathogens early in life, as infection with Epstein-Barr virus often is asymptomatic when it occurs in young children. Conflicting results have been reported regarding number of siblings, attendance in a day care center and exposure to animals during childhood in relation to MS risk, but common childhood infections and vaccinations do not seem to influence the risk of MS. In line with the hygiene hypothesis, two large meta-analyses have recently shown that infection with Helicobacter pylori is negatively correlated with MS. Moreover, a protective influence of helminth infection on MS has been observed in several, small clinical studies, but more knowledge is needed before a potential role of helminth-derived therapy in MS is determined. Also, it has been hypothesized that infection with the parasite Toxoplasma gondii could be protective against MS.
Insights
The hygiene hypothesis suggests lower early-life pathogen exposure increases immune disease risk. This theory is explored in relation to multiple sclerosis (MS), with some infections appearing protective.
Area of Science:
- Immunology
- Epidemiology
- Neurology
Background:
- The hygiene hypothesis posits reduced early-life pathogen exposure elevates immune-mediated disease risk.
- This hypothesis is relevant to the rising incidence of allergies and autoimmune diseases in industrialized nations.
- Several factors related to the hygiene hypothesis have been investigated concerning multiple sclerosis (MS) risk.
Purpose of the Study:
- To review the evidence linking the hygiene hypothesis to multiple sclerosis (MS).
- To examine the association between various childhood exposures and MS risk.
- To explore the potential protective roles of specific infections against MS.
Main Methods:
- Literature review and meta-analysis of existing studies.
- Analysis of epidemiological data on childhood exposures and MS.
- Examination of infectious agents and their correlation with MS incidence.
Main Results:
- Infectious mononucleosis, caused by Epstein-Barr virus, is an independent risk factor for MS.
- Infection with Helicobacter pylori shows a negative correlation with MS.
- Helminth infections and Toxoplasma gondii infection are hypothesized to be protective against MS, though further research is needed.
Conclusions:
- The hygiene hypothesis provides a framework for understanding some associations with MS.
- Specific infections like H. pylori and potentially helminths or T. gondii may have a protective effect against MS.
- Further research is required to elucidate the mechanisms and therapeutic potential of these infections in MS.
