Potential hazard to human and animal health from bacterial and fungal contaminants in small freshwater reservoirs

In general, the assessment of microbiological quality in aquatic systems focuses on the presence of some bacterial groups or species. Although Fungi is not a mandatory microbiological parameter, recently the WHO advises its detection/quantification. Its concentration and diversity varies greatly among the various types of aquatic systems. Fungi are mesophilic, dependent on organic matter to growth, and their presence can be associated with pollution. Depending on their concentration and diversity, fungi may pose a risk to human and animal health. The objective of the present work was to evaluate the presence of some bacterial indicators (Escherichia coli, faecal enterococci, among others) and fungi (total, yeasts and moulds) in freshwater reservoirs (water tanks) with different sources, sun exposures, anthropogenic and animal influences. Additionally, it was intended to assess the diversity of moulds. For this, filamentous colonies were isolated, purified and morphologically identified (whenever possible to the genus).

The three tanks differed in bacterial (presence of E. coli, faecal Enterococci, Staphylococcus aureus and Proteus vulgaris) and fungal (total and mould) contamination. Regarding moulds, 16 different taxa were identified and, depending on the water tank, Penicillium, Aspergillus and Fusarium genera and the Chytridiomycota phylum were the most representative. Some of the taxa isolated may pose a risk to human and animal health (dermatophytes such as Trichophyton, Aspergillus fumigatus, and some dematiaceous). The water reservoirs presented different fungal communities.

Although preliminary, the results show that freshwater tanks can be a source of potentially pathogenic bacteria and fungi, to humans and animals that use them.