Terrestrial Parasites Found In Oceans

A new study has found that at least three disease-causing parasites from land have attached to microplastics that reach oceans, thereby posing a risk to human and wildlife health.

The team at the School of Veterinary Medicine at the University of California, Davis, examined Toxoplasma gondii (Toxo), Cryptosporidium (Crypto) and Giardia, which can infect both humans and animals and how these parasites attach to polyethylene microbeads (found in cosmetics) and polyester microfibers (normally found in clothing and even fishing nets).

The research focused only on pathogens that are derived from terrestrial animal and human hosts. The existence of these pathogens in marine environments is due entirely to fecal waste contamination of the sea.

The results of the research indicate that the germs adhere better to the microfibers better than to the microbeads. In each case, the plastics serve as a “host” for the pathogen.

Microplastics that float along the surface could potentially travel long distances, spreading pathogens far from their original sources on land and bringing them to regions they would otherwise not be able to reach. Others sink to the sea floor where filter-feeding animals like zooplankton, clams, mussels, oysters, abalone and other shellfish abide.

In both cases, the parasites are harmful and can pose a risk to sea life and subsequently to humans who ingest contaminated fish and seafood.

Toxo, found only in cat feces, is linked to deaths of sea otters and some critically endangered wildlife. The parasite can cause lifelong disease, developmental and reproductive disorders in humans.

Crypto and Giardia cause gastrointestinal distress and can be deadly in children and others with underdeveloped or suppressed immune systems

"This work demonstrates the importance of preventing sources of microplastics to our oceans," said study co-author Chelsea Rochman, a plastic-pollution expert and assistant professor of ecology at the University of Toronto. "Mitigation strategies include filters on washing machines, filters on dryers, bio-retention cells or other technologies to treat stormwater, and best management practices to prevent microplastic release from plastic industries and construction sites."

The study was conducted in a inter-disciplined approach through a team of experts including microplastic researchers, parasitologists, shellfish biologists and epidemiologists. The co-authors emphasized the importance of collaboration to address human, animal and environmental aspects of the shared marine environment.