Association of bacterial load in drinking water and allergic diseases in childhood. Issue 6 (20th April 2020)

• Record Type: Journal Article
• Authors: Turkalj, Mirjana; Drkulec, Vlado; Haider, Sadia; Plavec, Davor; Banić, Ivana; Malev, Olga; Erceg, Damir; Woodcock, Ashley; Nogalo, Boro; Custovic, Adnan
• Is Part Of: Clinical & experimental allergy. Volume 50:Issue 6(2020)
• Page Start: 733
• Page End: 740
• Publication Date: 2020-04-20
• Subjects: atopy -- bacterial load -- children -- drinking water -- microbiota -- well water; Allergy -- Periodicals; Immunology -- Periodicals; 616.97
• DOI: 10.1111/cea.13605
• Languages: English
• ISSNs: 0954-7894

Abstract

Abstract: Background: Treatment of drinking water may decrease microbial exposure. Objective: To investigate whether bacterial load in drinking water is associated with altered risk of allergic diseases. Methods: We recruited 1, 110 schoolchildren aged 6‐16 years between 2011 and 2013 in Požega‐Slavonia County in Croatia, where we capitalized on a natural experiment whereby individuals receive drinking water through public mains supply or individual wells. We obtained data on microbial content of drinking water for all participants; 585 children were randomly selected for more detailed assessments, including skin prick testing. Since water supply was highly correlated with rural residence, we compared clinical outcomes across four groups (Rural/Individual, Rural/Public, Urban/Individual and Urban/Public). For each child, we derived quantitative index of microbial exposure (bacterial load in the drinking water measured during the child's first year of life). Results: Cumulative bacterial load in drinking water was higher (median [IQR]: 6390 [4190‐9550] vs 0 [0‐0]; P < .0001), and lifetime prevalence of allergic diseases was significantly lower among children with individual supply (5.5% vs 2.3%, P = .01; 14.4% vs 6.7%, P < .001; 25.2% vs 15.1%, P < .001; asthma, atopic dermatitis [AD] and rhinitis, respectively). Compared with the reference group (Urban/Public), there was a significant reduction in the risk of ever asthma, AD and rhinitis amongst rural children with individual supply: OR [95% CI]: 0.14 [0.03, 0.67], P = .013; 0.20 [0.09, 0.43], P < .001; 0.17 [0.10, 0.32], P < .001. Protection was also observed in the Rural/Public group, but the effect was consistently highest among Rural/Individual children. In the quantitative analysis, the risk of allergic diseases decreased significantly with increasing bacterial load in drinking water in the first year of life (0.79 [0.70, 0.88], P < .001; 0.90 [0.83, 0.99], P = .025; 0.80 [0.74, 0.86], P < .001; current wheeze, AD and rhinitis). Conclusions and Clinical Relevance: High commensal bacterial content in drinking water may protect against allergic diseases.