Association of Bacterial Load in Drinking Water and Allergic Diseases in Childhood

Abstract

To determine if high microbial content in drinking water alters the risk of allergic disease in children.Children aged 6 to 16 years living in Eastern Croatia between 2011 and 2013 were recruited for the study. The authors report that this area of Croatia is unique in that individuals have access to drinking water through 2 different supply systems: public mains or individual wells.There were 2 phases of the study. In phase 1, parents were asked to complete a survey regarding their child’s symptoms, physician-diagnosed illnesses, medication use and type of drinking water supply: public mains and/or individual wells. In phase 2, one-half of the study participant’s parents were randomly selected to complete a questionnaire about home location, farming practices, and socioeconomic status. Their children underwent skin-prick testing for 9 aeroallergens: dust mites, cockroach, molds (Alternaria and Cladosporium) and pollens (birch, hazelnut, grass, and ragweed). Data on the microbial content of drinking water from 1997 to 2007 were reviewed to ascertain information about early-life exposure for the study participants. Water samples were collected at random points from public mains and from each individual well in participating households.A total of 1110 children were recruited for phase 1 of the study, with 978 children fulfilling study criteria. A total of 51.5% (n = 504) of the children attended urban schools, and 48.5% (n = 474) attended rural schools. A total of 494 children accessed drinking water through the public main water supply, whereas 484 accessed it through individual wells. More than 90% of the 484 children with individual wells attended rural schools. There were only 21 children living in urban areas who accessed individual well water. There was a significant difference in the cumulative bacterial load in drinking water, with samples from individual wells having a much higher bacterial load: individual wells (6390 colony forming units per mL [4190–9550]) versus public (0 colony forming units per mL [0–0]); P < .0001. Children who had access to individual wells had significantly lower rates of lifetime prevalence of asthma (2.3% vs 5.5%; P = .011), atopic dermatitis (6.7% vs 14.4%; P < .001), and rhinitis (15.1% vs 25.2%; P < .001), compared with that of those children who had access to a public main water supply.Exposure to high microbial content in drinking water may confer protection against allergic disease development in childhood.Here is one more study that lends further support to the hygiene hypothesis revealing that high microbial exposures in drinking water may protect children against the development of atopic diseases. The authors also add another possible route of exposure to explain the lower prevalence of allergic disease found in those living in rural environments.