Related Experiment Video
Updated: Aug 6, 2026
09:02
A Method to Test the Efficacy of Handwashing for the Removal of Emerging Infectious Pathogens
Published on: June 7, 2017
Too clean, or not too clean: the hygiene hypothesis and home hygiene
S F Bloomfield1, R Stanwell-Smith, R W R Crevel
1London School of Hygiene and Tropical Medicine, London, UK. Sally.Bloomfield@ifhhomehygiene.org
Summary
The hygiene hypothesis suggests reduced childhood infections increase atopic disorders. However, evidence links lifestyle changes and decreased microbial exposure, not just hygiene, to rising allergies.
Area of Science:
- Immunology
- Epidemiology
- Environmental Health
Background:
- The 'hygiene hypothesis' proposes reduced early childhood infections increase atopic disorders.
- The term 'hygiene hypothesis' has led to misinterpretations, with evidence not fully supporting a direct link to domestic hygiene.
- Rising allergic disorders do not correlate with decreased pathogenic infections or improved domestic hygiene.
Purpose of the Study:
- To critically evaluate the 'hygiene hypothesis' and its relationship to atopic disorders.
- To explore alternative explanations for the rise in allergic diseases.
- To clarify the role of microbial exposure in immune system development.
Main Methods:
- Review of existing epidemiological and immunological evidence.
- Analysis of the correlation between infection rates, hygiene practices, and allergic disease prevalence.
- Examination of proposed alternative hypotheses, such as microbial deprivation.
Main Results:
- The increase in allergic disorders does not directly correlate with decreased infections or improved domestic hygiene.
- Fundamental lifestyle changes leading to reduced exposure to microbes and helminths are implicated.
- The original formulation of the 'hygiene hypothesis' may be too narrowly focused on hygiene practices.
Conclusions:
- The relationship between hygiene practices and atopic disorders is not definitively proven.
- Reduced exposure to diverse microbial species is a more likely driver of increased allergies.
- Renaming the hypothesis to 'microbial exposure' or 'microbial deprivation' hypothesis could improve focus and avoid misinterpretations regarding hygiene.
Related Concept Videos
01:23Hand hygiene
Asepsis is the practice of preventing or breaking the chain of infection. The nurse employs aseptic techniques to prevent the spread of microorganisms and reduce the risk of diseases. Hand hygiene is the cornerstone of aseptic techniques and is classified into medical and surgical asepsis. Medical asepsis includes hand hygiene and the use of gloves. Surgical asepsis, or the sterile technique, refers to practices that render and keep objects and areas free of microorganisms.
Hand washing...
Hand washing...
01:18Handwashing I: Introduction and Types of Equipment
Handwashing is hand hygiene with plain or antimicrobial soap and water to physically remove dirt, organic material, and microorganisms. However, it may not kill all microorganisms. The handwashing procedure requires a hand wash basin, liquid soap, paper towels, a domestic waste bin, and disposable nail cleaner as optional equipment.
Hand wash basins in clinical areas should have faucets that can be turned on and off without using the hands; that is, they should be non-touch or lever-operated.
Hand wash basins in clinical areas should have faucets that can be turned on and off without using the hands; that is, they should be non-touch or lever-operated.
01:10Homeostatic Imbalance
Homeostasis is the maintenance of a stable internal environment within the body, which is crucial for the proper functioning of cells, tissues, organs, and organ systems. The body has various control mechanisms that work together to regulate various physiological parameters such as temperature, blood pressure, pH balance, and fluid balance, to name a few. These control mechanisms are based on feedback loops that can be either positive or negative.
However, sometimes these feedback loops fail,...
However, sometimes these feedback loops fail,...
01:27The Oral Microbiota
The oral microbiome includes a complex ecosystem comprising over 700 microbial species, identified through genomic sequencing and culture-based analyses to date. This community includes a core microbiome, found universally among individuals, and a variable component influenced by environmental factors such as diet, lifestyle, and host genetics. Site-specific conditions, including oxygen gradients, pH levels, and nutrient availability, determine the spatial distribution of these microorganisms...
01:28Development of the Oral Microbiota
The establishment of the oral microbiome begins before birth, challenging the long-held belief that the fetal oral cavity is sterile. The presence of oral microbes such as Streptococcus and Fusobacterium in amniotic fluid suggests that microbial exposure may occur in utero, potentially through translocation from the maternal oral or gastrointestinal tract. This early colonization primes the neonatal immune system and sets the stage for subsequent microbial succession. Maternal health,...
01:28Microbiota of the Urogenital Tract
The human urogenital system, once thought to be sterile in healthy individuals, is now recognized as a complex microbial habitat. Advancements in molecular sequencing techniques have revealed that even in healthy adults, the kidneys and bladder harbor microbial populations similar to those found in the distal urethra, albeit in much lower abundance. These resident microorganisms, while generally innocuous, can become opportunistic pathogens under conditions that alter the urogenital...