February 18, 2006
Cat parasite a danger to otters – study
By Maggie Fox, Health and Science Correspondent
ST. LOUIS (Reuters) - A parasite carried in cat droppings
may be killing otters off the California coast, researchers
said on Saturday.
that a virus may be causing cancer in seals and toxins from red
tides that are a known threat to the endangered manatee may
also harm people.
The otter study may help explain why populations of the
frisky animals have not recovered from the 19th-century fur
trade, researchers said.
"Before I started this project I didn't think about things
like how much cat feces gets into the environment -- how what
we dump on our lawns and sidewalks flows into streams to rivers
and into the ocean," said Patricia Conrad, a professor of
parasitology at the University of California, Davis.
Conrad said 38 percent of live sea otters she tested
carried antibodies to Toxoplasma gondii, a single-celled
parasite that causes toxoplasmosis.
It was in 52 percent of dead otters, Conrad told a meeting
of the American Association for the Advancement of Science.
"What the sea otters are telling us is the problem is far
larger than a worry about cat litter. These parasites are in
the environment," Conrad said.
Toxoplasmosis does not usually make people or cats sick,
but is a known threat to pregnant women, who are cautioned
against handling cat litter or cat droppings.
In otters, it gets into their brains. When Conrad studied
the bodies of dead otters, they found 17 percent had "very
severe lesions" in their brains caused by the protozoa.
While the parasite infects rodents and birds, they are
unlikely to spread it. "Of all the animals that get infected
with this parasite ... cats are the only host in which the
parasite undergoes sexual multiplication and results in the
tough, egg-like stage that is passed in the feces," Conrad
It may be getting into mussels and oysters, and Conrad's
team is testing that idea now.
"Probably the most important thing we can do is manage our
cats more responsibly. The most important thing is probably to
keep cats indoors," advised Conrad, a cat owner.
Frances Gulland of the Marine Mammal Center in Sausalito,
California, has found that 18 percent of stranded adult
California sea lions have cancer. Her team has linked this with
a herpes virus called otariine herpesvirus-1, which is related
to a virus called HHV-8 known to cause Kaposi sarcoma in people
with the AIDS virus.
The seals with cancer also have higher levels of chemicals
known as PCBs in their fat, Gulland said. PCBs are pollutants
produced by several industries and also linked with human
In a separate study, Gulland found that diatoms, tiny
floating sea creatures, produce a toxin that can kill seals.
The toxin, called domoic acid, is found in "blooms" of algae
that have become more common off the U.S. Pacific Coast.
Similar algal blooms called red tides are becoming more
common off the Gulf Coast and Gregory Bossart of the Harbor
Branch Oceanographic Institution in Fort Pierce, Florida, has
found in the past that manatees can be sickened by toxins
produced by the algae called brevetoxins.
On Saturday he presented evidence that these toxins can
also affect people, and that they can be found in sea grasses
even without a red tide present.
"The toxin might not make you sick or kill you (but) it may
predispose you to other diseases," Bossart told a news
"To me that is significant because these red tides are
becoming more common in the Gulf of Mexico."
He said statistics released last month showed that 2005 was
the second deadliest year on record for Florida's endangered