Toxigenic Vibrio cholerae can cycle between environmental plastic waste and floodwater: Implications for environmental management of cholera

Abstract

Globally, there has been a significant rise in cholera cases and deaths, with an increase in the number of low- and middle-income countries (LMICs) reporting outbreaks. In parallel, plastic pollution in LMICs is increasing, and has become a major constituent of urban dump sites. The surfaces of environmental plastic pollution can provide a habitat for complex microbial biofilm communities; this so-called 'plastisphere' can also include human pathogens. Under conditions simulating a peri-urban environmental waste pile, we determine whether toxigenic V. cholerae (O1 classical; O1 El Tor; O139) can colonise and persist on plastic following a simulated flooding event. Toxigenic V. cholerae colonized and persisted on plastic and organic waste for at least 14 days before subsequent transfer to either fresh or brackish floodwater, where they can further persist at concentrations sufficient to cause human infection. Taken together, this study suggests that plastics in the environment can act as significant reservoirs for V. cholerae, whilst subsequent transfer to floodwaters demonstrates the potential for the wider dissemination of cholera. Further understanding of how diseases interact with plastic waste will be central for combating infection, educating communities, and diminishing the public health risk of plastics in the environment. Plastics colonised by human pathogens can have significant environmental and human health implications. The lightweight and buoyant properties of plastic facilitates enhanced distribution throughout the environment. This persistence and distribution of plastic contamination increases the risk of direct human exposure. This study demonstrates that human pathogenic Vibrio cholerae can colonise plastic waste and survive under environmental conditions; importantly, this pathogen can subsequently be transferred to floodwater, increasing the potential for the spread of cholera. Crucially, the concentration of V. cholerae recovered from the surface of plastic pollution, and in the surrounding floodwater, remains high enough to pose a significant threat to human health. Our results attest to the increased co-pollutant risk of plastic pollution, and the heightened risk of human exposure to a dangerous human pathogen in the environment.

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