Microbiological drinking water safety is traditionally monitored mainly by bacterial parameters that indicate faecal contamination. These parameters correlate with gastro-intestinal illness, despite the fact that viral agents, resulting from faecal contamination, are usually the cause. This leaves behind microbes that can cause illness other than gastro-intestinal and several emerging pathogens, disregarding non-endemic microbial contaminants and those with recent pathogenic activity reported. This white paper focuses on one group of contaminants known to cause allergies, opportunistic infections and intoxications: Fungi. It presents a review on their occurrence, ecology and physiology. Additionally, factors contributing to their presence in water distribution systems, as well as their effect on water quality are discussed. Presence of opportunistic and pathogenic fungi in drinking water can pose a health risk to consumers due to daily contact with water, via several exposure points, such as drinking and showering. The clinical relevance and influence on human health of the most common fungal contaminants in drinking water is discussed. Our goal with this paper is to place fungal contaminants on the roadmap of evidence based and emerging threats for drinking water quality safety regulations.

Washing machines (WMs) are convenient places for fungal colonization. This study is focused on fungal diversity of WMs, and investigates relationships between habits of WM users and colonising species. Housekeeping conditions and habits were assessed in Hungary with a questionnaire. Several fungal species were identified by microscopy and sequence analysis of diagnostic loci. Based on the results, 32 % of the sampled WMs were highly polluted with various species of fungi. Forty six percent of them were colonised also by opportunistically human pathogenic species. In total, 32 yeast and 39 filamentous fungal strains were isolated. Growth tests were conducted with five selected taxa (Cutaneotrichosporon dermatis, Cystobasidium slooffiae, Meyerozyma guilliermondii, Candida parapsilosis and the Fusarium oxysporum species complex (FOSC)) to ascertain their tolerance ranges. None of the examined isolates were able to grow >50 C, 4.10 < pH < 10.88. FOSC could grow at high salinity. More species were detected in WMs operated in rooms without heating systems (p ¼ 0.0025). The number of species was higher in WMs located in the kitchen than the ones kept in bathroom or in other rooms (p ¼ 0.0205). WMs may serve as a reservoir of pathogenic fungi, the presence of which may depend on the usage of these devices.

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