![]() ![]() What physical and chemical features of the proposed vector allow bacteria to remain viable?ĭo bacteria remain viable for a sufficient amount of time to encounter a new environment or host? Organisms are more abundant on floating debris than in ambient environment or other potential vectorsĭo physical and chemical features of the proposed vector preference the recruitment and survival of bacteria relative to the ambient environment and/or other potential vectors?ĭebris is dispersed by currents of water and air or by the movement of an intermediate host animal and the associated rafting organisms survive this journey Related ecological concepts (e.g., preferential recruitment, survival, rafting and pollution (31,32,37−39))Īppropriate question for scientific study of the vector frameworkĪre pathogenic bacteria found on the polymer in the environment? ![]() (15,34)Įpidemiological (Bradford-Hill) criteria (36) These steps are generally neglected in “plastisphere” discussions, which are often based solely on the colonization stage and represent presence/absence data of bacteria on a polymer. First, bacteria must be able to colonize the substratum (colonization), they and the substratum must then remain viable until they encounter a host (survival), finally they must colonize the organism (transfer) in sufficient numbers to cause disease (disease). (33) Conceptually, this process can be divided into a series of smaller processes that can be investigated using surveys and experiments ( Table 1). ![]() (31,32) Considering this, a vector is any agent that aids in the transmission of an organism to a potential host. (30) We, however, propose that the concept of a vector draws not only from epidemiology but also from “rafting” by invasive organisms in ecology. The Bradford-Hill vector criteria ( Table 1) is a framework ingrained in epidemiology that over the last 12 years has been adapted to address ecological questions. (26−28) Therefore, a more interdisciplinary systematic and critical review of the evidence is required to transcend disciplinary boundaries and meld insights to provide more comprehensive information about the quality, quantity, and levels of uncertainty in the available evidence. As such they could be constrained by the cultural norms of their discipline (e.g., common aims, methods, paradigms). (17,19,25) These reviews vary in their stated methods and were largely monodisciplinary. (22−24) In contrast, other reviews suggest the evidence is insufficient. There is, however, a major debate, with some reviews suggesting there is sufficient evidence to show that bacteria preferentially colonize plastics, (7,16,20,23) resulting in a distinct assemblage, (6,8,12−14,16,21,23) which survives for longer periods (6) and can cause disease. Several reviews (6−22) and an opinion-piece (23) have summarized our understanding of bacterial contamination of debris and their associated health and environmental impacts. Our analysis shows a need for linked structured surveys with environmentally relevant experiments to understand patterns and processes across the vectoral stages, so that the risks and impacts of pathogens on polymers can be assessed with more certainty. One laboratory experiment demonstrated plausibility for polymers to be colonized by a potential pathogen ( Escherichia coli), survive, transfer, and cause disease in coral ( Astrangia poculata). No study showed bacteria can preferentially colonize, survive, transfer, and cause more disease on polymers compared to other environmental media. Further, 8% of studies investigated μm-sized polymers with most (58%) examining less pervasive cm-sized polymers. Only 11% of studies identified potential pathogens, with only 3% of studies confirming the presence of virulence-genes. We show 58% of studies investigated the colonization-stage alone but used this as evidence to classify a substratum as a vector. We then systematically and critically reviewed 111 environmental and medical papers. We integrated causal frameworks from ecology and epidemiology into one interdisciplinary framework with four stages (colonization, survival, transfer, disease). Pathogens and polymers can separately cause disease however, environmental and medical researchers are increasingly investigating the capacity of polymers to transfer pathogenic bacteria, and cause disease, to hosts in new environments. ![]()
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