Hygiene levels in a contemporary population cohort are associated with wheezing and atopic eczema in preschool infants

Abstract

Background: The hygiene hypothesis states that insufficient exposure to certain infectious agents during childhood increases the risk of developing asthma and atopic diseases. Improvements in hygiene levels may be partly responsible for this decline in exposure. Aims: To assess whether hygiene levels in infancy are associated with wheeze and/or atopic eczema, independent of a number of possible confounding factors. Methods: Data were gathered from the Avon Longitudinal Study of Parents and Children (ALSPAC). Parental self completion questionnaires provided symptom data on infant wheeze and atopic eczema at 0-6 months and 30-42 months, respectively. A simple hygiene score was derived using questionnaire responses at 15 months, which ranged from least hygienic to most hygienic. Multivariable logistic regression models analysed the effect of hygiene scores on health outcomes, while adjusting for a number of important confounding variables. Results: Increasing hygiene scores were independently associated with wheezing (OR = 1.04; 95% CI: 1.00 to 1.08) and atopic eczema (OR = 1.04; 95% CI: 1.01 to 1.07) between 30 and 42 months, but not in the first six months. The odds ratio was higher for atopic eczema if the rash was reported to have become sore and oozy (OR = 1.09; 95% CI: 1.02 to 1.16). Conclusions: High levels of hygiene at 15 months of age were independently associated with wheeze and atopic eczema reported between 30 and 42 months, and there was an increased risk for children with more severe eczema during this period. The importance of hygiene in public health should not be dismissed; however, the creation of a sterile environment through excessive cleanliness may potentially be harmful to the immune system.

Neonatal programming of innate immune function

“…The long-term effects of an inflammatory challenge at or near parturition in the human appear to be overwhelmingly negative (1,16,64,74). However, it is also known that lack of exposure to appropriate immune stimuli in childhood can enhance the risk of developing autoimmune diseases (62,73). We have seen in the rodent that a P14 challenge with LPS does not lead to obvious deficits in the later life ability to respond to a dose of LPS sufficicent to produce sepsis (79).…”

Is eczema really on the increase worldwide?

“…36,37 The increasing use of soaps, shower gels, shampoos, and other harsh cleansing products, 38 especially in developing country cities undergoing rapid economic change, could be one reason for the comprehensive increase in eczema prevalence observed in our study and is further supported by a previous cohort study that showed an independent association between an increased hygiene score (that included the frequency of washing/wiping hands and faces and bathing practices of young children) and subsequent eczema risk. 39 …”

Endothelial Dysfunction in Childhood Infection

“…From these responses, the child's mean hygiene score was derived (ranging from least hygienic to most hygienic). 15 Similarly, a mean infection score was created from questionnaires for the age periods Ͻ6 months, 6 to 18 months, 18 to 30 months, 30 to 42 months, and 59 to 81 months, which gave values from 0 to 7. The infection score at each time point was the number of infections (diarrhea, vomiting, cough, high temperature, cold, earache, and ear discharge) reported.…”