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Volume 15, Issue 36 ~ September 6 - September 12, 2007


From the Editors of E/The Environmental Magazine

Feline Parasite Kills Sea Otters

Kitty litter is the culprit

How is it that flushing cat litter down the toilet has negatively affected sea otters? What is the responsible way to dispose of cat waste?

–Margo Boss, San Dimas, Cal.

Cat feces can contain Toxoplasma gondii, a parasite that gets into feline systems from the eating of infected rodents, birds or other small animals, according to Dr. Melissa Miller of the California Department of Fish and Game. Cats later expel in their droppings parasites — sometimes hundreds of millions at a time — that can survive in soil for over a year and that also contaminate drinking water.

Most municipal sewage treatment systems are not designed to filter out Toxoplasma, so the parasites also get into storm drains and sewage outflows that carry them to near-shore ocean waters. Here, researchers have found, sea otters prey on mussels, crabs and other filter feeders that can concentrate Toxoplasma. Hundreds of sea otters have been found dead on California beaches in recent years with no obvious external injuries; Miller and other scientists think that Toxoplasma may be the cause.


Toxoplasma can also cause health problems for people, especially those with compromised immune systems (such as AIDS patients). While not typically fatal in humans, Toxoplasmosis, as the disease is called, can also cause birth defects, blindness or brain damage in children born to infected mothers.

The best way to avoid the infection is to use plastic gloves when changing the litter box and to wash hands thoroughly afterward. It is also advisable to stay away from raw or undercooked meat and uncooked or unwashed vegetables that may have been contaminated by manure (although felines are the parasites’ primary host, other warm-blooded animals and birds can also be carriers). Toxoplasmosis doesn’t normally spread from person to person (with the exception of pregnant women, who can pass it on to their fetuses), but in rare instances it has contaminated blood transfusions and organs donated for transplantation.

So what’s a responsible cat owner to do about dumping the contents of kitty’s litter box? Cat owners can start by keeping their cats inside, where they are not able to hunt the small animals that can pass Toxoplasma along to them in the first place, according to Dr. Patricia Conrad, a veterinarian and parasitologist at the University of California at Davis who has studied Toxoplasma contamination in sea otters. (Bird lovers have been requesting this for years.)

Those cat owners unwilling to keep their cats inside should do their part by at least not flushing cat litter or cat feces down the toilet. Cat fecal material should be placed in double plastic bags and included in the household trash. It will end up in the landfill, where precautions are taken to prevent environmental contamination.

For more information:

• “What’s Killing California Sea Otters?”: www.seaotterresearch.org.

• “Parasite in Cats Killing Sea Otters”: www.research.noaa.gov/spotlite/archive/spot_otter.html.


