These pathogens can attach to microplastics and infect animals and humans.

An international research team has shown that three pathogens can bind to and move through microplastics, increasing the risk of spread.

Credit: University of California, Davis

Terrestrial microorganisms responsible for potentially dangerous diseases for humans and wildlife can attach themselves to microplastics and spread in the oceans, potentially having a serious impact on health (including ours) and the ecological balance. Microplastics, which encompass all plastic fragments less than or equal to 5 millimeters in diameter, are indeed ingested by many marine animals, including mollusks, crustaceans and fish. If infected with the aforementioned pathogens, animals can become infected and become ill, with the risk of transmitting infections to humans through the food chain.

An international research team led by scientists from the University of California, Davis, who worked closely with colleagues from the School of Veterinary Medicine and Biomedical Sciences, sounded the alarm about the ability of microplastics to carry pathogens. in Ecology and Evolutionary Biology, University of Toronto (Canada) and other centers. The scientists, coordinated by Prof. Karen Shapiro, professor in the Department of Pathology, Microbiology, and Immunology at the University of California, came to their conclusions after conducting experiments with three specific microorganisms, zoonotic protozoa, responsible for diseases associated with eating shellfish.

The pathogens involved in the study were Toxoplasma gondii, which causes toxoplasmosis in warm-blooded animals (such as marine mammals) and is commonly found in cat feces; Giardia and Cryptosporidium, which can cause life-threatening gastrointestinal illness (such as diarrhea) in young children and immunocompromised people. To determine the ability to bind to microplastics in seawater, Prof. Shapiro and his colleagues set up a special experiment in the laboratory using two different types of materials: polyester microfibers, which are mainly found in fabrics (and which end up in wastewater during machine washing) and polyethylene. . microspheres, which are mainly found in cosmetics and personal care products. Tests showed that all three pathogens adhere more easily to clothing microfibers than to polyethylene microspheres, but all microplastics have been implicated in contamination.

“Microplastics can actually move pathogens, and these microbes end up in our water and our food,” Professor Shapiro said in a press release. There is no evidence that this infection ever actually occurred, but the University of California points out that several animals, such as sea otters, Hector’s dolphins, and Hawaiian monk seals, were killed by toxoplasmosis, a disease that should only affect animals. land animals. Details of the study “Association of zoonotic protozoan parasites with microplastics in seawater and implications for human and wildlife health” were published in Scientific Reports.

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