A Hawaiian monk seal under intensive care at the Marine Mammal Center in Kailua-Kona died last week.
RW22, also known as Kolohe, was discovered by Ko Olina on Oʻahu last month. He was malnourished with fishing gear caught in his stomach.
He also suffered from toxoplasmosis, a parasite found in cat feces, officials said. Toxoplasmosis can enter the ocean through rainwater runoff and infect marine animals.
Dr. Sophie Whoriskey had been working with RW22 since he was admitted to the center.
"When RW22 came in, he was in a pretty compromised state, so we put him on an aggressive round of medications to treat both the parasite itself, as well as any inflammation that was going on in his body associated with that parasite," Whoriskey said.
"He kind of rallied a little bit and showed us some initial improvement and started eating a little bit. But right around the four week mark or so, he started to not feel well," she said.
"This is a complicated disease process that we’re just starting to understand in these animals, so I don’t know exactly what happened with him. But it looks like he probably had some kind of reoccursion with the disease, so that disease flared up again and it didn’t respond as well to therapy unfortunately this time around," Whoriskey told Hawaiʻi Public Radio.
A team of veterinarians began a post-mortem examination on Monday morning.
They found symptoms consistent with toxoplasmosis, but nothing has been determined yet. Tissues and blood work from RW22 will be sent to various labs in Hawaiʻi and the continental U.S.
Various countries in Europe and New Zealand have a vaccine for toxoplasmosis found in sheep called Toxovax. It cannot be used for other animals, and it's currently unavailable in the U.S.
Cat owners should keep their felines indoors and dispose of litter in a sealed bag to prevent toxoplasmosis infection in other animals.
Stray cats have no predators in Hawaiʻi and their numbers have ballooned. Marketing research commissioned by the Hawaiian Humane Society in 2015 estimated Oʻahu alone had 300,000 feral cats.
