A review on present and future microbial surface water quality worldwide

Abstract

High incidences of waterborne diseases occur due to consumption of contaminated surface water sources globally. Monitoring and health risk assessment is required to understand whether the surface water is appropriate for irrigation, recreational and domestic use. It is vital to identify the reasons that influence the dynamic dispersal of waterborne pathogens and faecal indicator bacteria (FIB). The projected increase in precipitation and higher temperatures due to climate change are likely to exacerbate the problems of faecal contamination. This could be further compounded by the rapid change in socio-economic conditions in developing countries. Therefore, improved understanding of the influence of climate change and socio-economic development on microbial water quality is very important to reduce future health risks. Even with the high relevance for public health, few studies currently exist on the fate and transport of pathogens/FIB in tropical regions, and only a few studies have quantified the relationship between the pathogens/FIB concentrations and climate and socio-economic changes globally. Furthermore, most studies have been based on FIB. Other detrimental pathogens (e.g. infectious bacteria, viruses, and protozoa) have not been included in most of the studies due to difficulties associated with detecting these pathogens in the environment. There are differences between temperate and tropical ecosystems and due to such differences waterborne pathogens may behave differently in the two systems. In this article, besides reviewing existing literature on microbial monitoring, modelling, health risk assessment and future scenario analysis, we focus on the differences in microbial behaviour between temperate and tropical ecosystems. We also highlight some of the key present-day gaps and reflect on possible future guidelines for research in this domain.