A parasite carried in cat feces is being blamed for the recent deaths of three endangered Hawaiian monk seals on Oahu.

The state Department of Land and Natural Resoures and state Department of Health issued a press release today saying the death could have been preventable.

“Cats are the only known reproductive host of the toxoplasmosis parasite. It reproduces in the feline digestive system,” the press release said. “A single cat can excrete 145 billion eggs per year in its feces. Once released into the environment, these eggs can infect other animals, including humans, both on land and in the ocean. Toxoplasmosis parasites create cysts in muscle and organ tissues and can cause inflammation of the heart, liver, and brain.”

“In addition to preying on native wildlife, cats pose a significant health risk to people, marine wildlife and birds,” said DLNR Chair Suzanne Case, encouraging the public not to feed cats and other animals near water.

According to the state, toxoplasmosis can also infect Hawai‘i’s native birds, including the nēnē and the newly released Hawaiian crow, the ʻAlalā.

“Feeding cats near water obviously increases the risk of transmission but, given the nature of the watersheds in Hawai‘i, cats almost anywhere are probably contributing to the problem,” Case said. “The cysts can live for months in soil and can wash into streams and runoff and be carried into the ocean from almost anywhere. Feeding cats at state parks, boat harbors and other coastal areas increases the risk of transmission because the cysts don’t need to travel very far to get into the ocean.” Case added, “Frankly, feeding cats anywhere where their feces can ultimately wash into the ocean is a problem.”