Otter-Killing Parasite Also Possible Human Threat

After four sea otters died from a rare form of toxoplasmosis, scientists are warning of a threat to humans
By Steve Huff,  Newser Staff
Posted Mar 24, 2023 4:20 PM CDT
Otter-Killing Parasite Also Possible Human Threat
File photo of an otter.   (Brittany Murray/Orange County Register/SCNG via AP)

After discovering four sea otters died due to infection by what a UC Davis press release termed an "unusually severe" form of toxoplasmosis, scientists are sounding an alarm. Science reports that veterinary pathologist Melissa Miller first noted the infection in a dead otter in 2020. It wasn't that unusual that the otter's body carried Toxoplasma gondii, which causes toxoplasmosis, but typically the parasite attacks the central nervous system. In this case, the otter reportedly was killed by "an acute infection" that overwhelmed its immune system long before it reached the creature's brain. In the years since, more California sea otters have died from the same novel infection, and researchers are growing concerned about its spread.

As the San Francisco Chronicle reported this week, the deaths of four otters from the same strain between 2020 and 2022 could hint at a larger threat to marine life in general and to humans as well. The deaths were a possible warning that the parasite is climbing its way up the food ladder. A study in Frontiers in Marine Science co-authored by Miller says the new strain—referred to as COUG T. gondii—is "atypical and rare." It kills quickly, and is found in the body fat, digestive system, and muscle tissue of its victims.

According to Science, it's possible the otters acquired the parasite from eating clams, and Miller's study indicates COUG T. gondii can spread through drinking water with the germ in it. This means that it could ultimately pose a problem for people who eat seafood or drink contaminated water. Though COUG T. gondii, which was originally discovered in mountain lions in British Columbia, has not been found in humans yet, scientists are on alert for signs it is spreading across the food chain. (Read more parasites stories.)

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