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Chain of cat feces can harm humans, sea otters
A young cat can shed up to 100 million oocysts -- little egg-like structures -- in its feces.
February 19th, 2012
08:28 PM ET

Chain of cat feces can harm humans, sea otters

There's more to cat excrement than meets the eye, and it may have the potential to cause disease in sea otters and humans alike.

A young cat can shed up to 100 million oocysts - little egg-like structures - in its feces. All it takes is one oocyst to cause an infection of Toxoplasma gondii.

Largely, the parasite is asymptomatic in humans, but it can sometimes cause problems for infants born to infected mothers - including hearing loss, mental disability and blindness. People with compromised immune systems, especially those who have HIV/AIDS, may also develop serious complications.

Researchers are trying to understand why marine mammals in the Pacific Northwest started dying of protozoal diseases starting in 2000; before then, there weren't any  documented cases, but samples from the Pacific Northwest have found a rate of about 4% of protozoal disease among stranded animals, says Michael Grigg, investigator at the National Institutes of Health.

Grigg and other experts discussed these issues Sunday at the American Association for the Advancement of Science (AAAS) annual meeting in Vancouver.

Cat feces may be part of the explanation, the scientists said.

When humans settle near shorelines, that can accentuate land-to-sea pollution. The toxoplasma gondii oocysts from cats can get into the ocean through storm runoff. From there, it can get into mussels and other bivalves that sea otters eat, for example. Humans who eat raw shellfish may likewise be at risk.

Up to 25% of Americans are infected with toxoplasmosis, and in some parts of Europe it's as much as 50%, Grigg said. Humans carry it throughout their lives. It's not known why there are more people who have the infection in Europe, although dietary habits (eating raw meat/fish) be a factor.

There are also strains of this parasite in nature in French Guiana and Suriname that are lethal to people, Grigg said.

Over the past few years,  scientists have been investigating a new form of Toxoplasma gondii ominously called Type X. It was first discovered in sea otters, and it's a combination of the familiar Type II strain and a unique strain of the parasite. It's unclear whether Type X is more serious than Type II, but Type X represents about 40% of infections.

In the few cases where Type X has been found in humans, it was problematic, but there were other immune system compromising factors - one patient was elderly, and one had had a transplant of some kind, Grigg said.

Toxoplasma gondii oocysts can't be destroyed with ultraviolet light or chlorine bleach - only freezing or boiling can kill them, Grigg said. For instance, there was a big outbreak in 1995 in Victoria, British Columbia, likely because the municipal water system was using unfiltered water.

Not all cats have toxoplasmosis, but a large majority do get infected, Grigg said. And they only secrete oocysts when they're young. But if 10% of the 86 million cats owned as pets in the U.S. were infected, that's still a whole lot of little parasite-infecting eggs.

That doesn't mean you shouldn't eat shellfish at all. Pay attention to to where it's harvested and when, says Melissa Miller of the Marine Wildlife Veterinary Care and Research Center in California. But there could be issues with raw or undercooked foods of all kinds, including shellfish. "There's far more that we don't know than we know," she told reporters.

There's ongoing research into a Toxoplasma gondii vaccine for cats, although one is not available yet.

In the meantime, you can take some precautions to prevent parasites from your cat's litter from getting into the water. Miller says she picks out the poop from the litter box and puts it into plastic bags and sends it to an approved landfill. Miller says she also keeps her cats indoors.

And even though parasites can recombine into different parasites, Grigg says we shouldn't be worried about a new toxoplasma parasite that's truly catastrophic to the human species.

"What we would expect is that nature will sort out what’s the right fit, the strain that doesn’t cause too much disease and can be maintained in nature," Grigg told CNN. "I don’t think there’s some big pathogenic strain that’s going to emerge and kill a lot of people."


soundoff (251 Responses)
  1. JustaGuy

    Easy solution. Stop eating cat poop! Although that will be kinda difficult to get third world countries to adhere to.

    February 21, 2012 at 13:56 | Report abuse | Reply
    • robby

      This is terrible news for my 6-year old son. We were planning is birthday party and I had purchased 2 barrels full of cat feces for he and his friends to roll around in. The people at Feces-For-Fun told us that our purchase is non-refundable, so now
      we're really stuck.

      February 21, 2012 at 15:31 | Report abuse |
    • Liliangrae

      It is NOT about eating cat poop. The infection can be conferred in other ways, that is way it is recommended that pregnant women do NOT change litter boxes.

      February 21, 2012 at 19:53 | Report abuse |
    • Funny

      hahahahahahaaaaaaaa robby.

      February 22, 2012 at 06:25 | Report abuse |
    • Elizabeth

      Most people do not wash hands well enough or often enough. In another study, e-coli was found on the hands of most men and some women. Washing hands after petting your cat, changing litter, or sweeping and dusting is very helpful.

      February 26, 2012 at 00:05 | Report abuse |
  2. anonymous

    duh... fecal matter is unhealthy! wow! who would have thought that? sheesh.... I could have told them not to play with p o o p

    February 21, 2012 at 14:49 | Report abuse | Reply
  3. Sam

    Yes we should stop eating cat poop. Another option is to get rid of sugared cereals. Seems to me their both the same.

    February 21, 2012 at 14:55 | Report abuse | Reply
  4. Debbie Bates

    Anyone who does TNR knows our opposition throws out the "t.gondii" card at the drop of a hat. As others have stated, anyone with half a brain knows feces is unhealthy....no matter which animal drops it. There are far more frightening things to worry about than the "possibility" of infection....and most of them are MAN-MADE....think high fructose corn syrup!

    February 21, 2012 at 15:08 | Report abuse | Reply
    • Elizabeth

      The corn syrup is made in an unnatural process adding toxins. Most people don't know this apparently. I've met cancer patients who say it makes them nauseous, and whose health improved when they stopped eating or drinking products containing corn syrup.

      February 26, 2012 at 00:08 | Report abuse |
    • larry

      what is your solution to cat over population? I say license cats and use money to educate cat owners on being responsible. Letting ones cat run loose is no good.

      May 26, 2012 at 00:11 | Report abuse |
  5. Mr Grumpy

    "and in some parts of Europe it's as much as 50%" I always knew the French would eat anything....

    February 21, 2012 at 16:13 | Report abuse | Reply
  6. Dan Bednarik

    Then don't eat cat feces.

    February 21, 2012 at 17:00 | Report abuse | Reply
  7. Deb Thomas

    Another thing we must protect our marine wildlife from. Please keep up to date on the threat from Pebble Mine to our marine life also!
    Pacific Seafood Processors now opposed to Pebble mine
    http://www.alaskadispatch.com

    This issue could fundamentally change the landscape and way of life in rural Alaska.

    ADN doesn't think it's front page news, I do.
    Read more here: http://www.adn.com/2012/02/16/...

    Deb Thomas
    Nikolaevsk, Alaska

    February 21, 2012 at 17:57 | Report abuse | Reply
  8. don't eat poop

    Hi. I'm going to add yet one more 'well then don't eat poop' comment because jokes are always grow funnier when they are repeated over and over.

    February 21, 2012 at 18:26 | Report abuse | Reply
    • Frank

      No wait... hahahahaha.. I've got one... hahahahahaha... don't.. hahahahah BREATH POOP! AHAHHAHAAHHAHAHAA!!!!

      February 21, 2012 at 18:31 | Report abuse |
  9. greendg1

    To anyone defending owning a cat, you're infected with toxoplasma gondii ominously Type X

    February 21, 2012 at 19:56 | Report abuse | Reply
    • Elizabeth

      Cats are the best defense against mice and the hanta virus.

      February 26, 2012 at 00:10 | Report abuse |
    • Nutheti

      Y'know, it is really spiapiodnting to this older woman who has a passel of cats to discover that young men these days don't know how to read critically or to think. That is a report on junk science, as anyone who read this passage (and who passed grade eight) should know:So the parasite has evolved a complicated system for taking over its hostse28099 brains to increase the likelihood that theye28099ll be eaten by cats.How? Scientists are still figuring that out. Research conducted this year by Toxo expert Robert Sapolsky of Stanford, and also by Joanne Webster, professor of parasite epidemiology at Imperial College London, has found that Toxo actually causes rats to become attracted to the smell of cat urine.Might Toxo explain why some humans develop an unhealthful attraction to cats and apparently become immune to the smell of their urine? And might that explain the mystery of crazy cat ladies? e2809cThat idea doesne28099t seem completely crazy,e2809d Sapolsky says. e2809cBut theree28099s no data supporting it.e2809dAnyone who falls for this kind of leap from what is really known about brain activity to wild interpretations is a well I'll stop there, out of politeness.

      March 5, 2012 at 20:44 | Report abuse |
  10. Sandra C

    1: Keep cat litter tray well away from cooking/eating areas. 2: Use Latex gloves when cleaning said litter tray, and then wash hands afterward. Jeeze, what's so damned difficult about that?

    February 21, 2012 at 21:39 | Report abuse | Reply
  11. TR

    Why is it that cats have more rights than dogs? When dogs relieve themselves outside of their owner's property, their owners are expected, by law, to pick up the mess. However, when cats relieve themselves, it's everyone else's problem except the cat owner.

    February 21, 2012 at 21:48 | Report abuse | Reply
  12. Brenda

    Cats bury it, TR. And if they're indoor pets, hopefully the owner changes the litter box. I am the only one in my family who seems to have this skill. That and changing the toilet paper roll. It's amazing what a college education can do for you.

    February 21, 2012 at 23:02 | Report abuse | Reply
    • Lori

      Cats do NOT bury it! At least, not where I live–our side yard is one big pile of cat poop, and I have begun trapping and taking cats to the pound because I am tired of the fecal material all over the place, both the sight, smell, and risk for disease. I have been told that the only way to sterilize my soil is to coat it with, and mix in, boric acid powder and/or a heavy brine solution, both of which will also kill the vegetation there. We will do it anyhow, and then plan to do a rockscape with sharp gravel, as we have been told that the gravel will keep any untrapped cats from using the side yard as a bathroom. Totally disgusting, and scary when considering the possible health effects.

      December 20, 2012 at 02:49 | Report abuse |
  13. Arthur Bumblast

    Cats are meant to live outside. They're "fake" friendly with man. They mimic love to get food. The don't love any human being like a dog does. I don't allow them near my home. I don't kill them but I do shoot them with an air gun using rubber bullets. They never come back. If you feed them, they will pee on your doors and walls to mark their territory. They'll poo in your vegetable garden and bury it spreading disease and illness. No. I don't let those diseased creatures anywhere near my home.

    February 22, 2012 at 02:04 | Report abuse | Reply
    • Elizabeth

      I'm sure that mice and rats don't have fleas in your universe; there are deadly diseases people can get from mice. People shouldn't let their pets roam the neighborhood, I agree, but you shouldn't be shooting them either. I have indoor cats, and they have always been very friendly, and not just when food is expected.

      February 26, 2012 at 00:14 | Report abuse |
  14. Rich

    This info is not brand new news to me. I first heard that pregnant women should not change/clean kitty litter about five or six years ago. Whats the matter, have they started making serving dishes from the poop or something?

    February 22, 2012 at 09:10 | Report abuse | Reply
  15. Michele

    People should keep their cats indoors. Our neighbors' cats that they allow to run free on our farm and the native prairie we've spent years and a lot of money developing. The cats hunt and kill songbirds, poop in my garden and flowerbeds, and are not welcome. I am TIRED of seeing dead bird carcasses oh the farm, and on the native prairie. II WANT the native animals hunted by the cats to survive. There are also feral cats–folks in the nearby town tend to bring them out here to the "country" when they don't want them anymore. I wish they'd think about what miserable lives those poor cats lead. The local Humane Society will sterilize feral cats (assuming we can catch them) but then insist we take them back and release them. Why do the cats have more rights than the native birds and rodents?

    February 27, 2012 at 21:49 | Report abuse | Reply
  16. Jakub

    How barbaric! I'm not relaly a fan of home-school myself, but, as an American, I am glad that we have the option to home-school, because many children need to be saved from harsh, inhumane treatment such as that which your son received, or for other reasons, such as to escape bullying, a poor education, or an anti-Christian agenda. I am thankful that the schools where I live are rural, locally controlled and taught by people who are our friends and neighbors, and still permit Christian things like vocal prayers over your lunch, Christian T-shirts, Christmas carols sung at Christmas plays, Christian movies (my son's history teacher showed Ben Hur once during class), etc. But not everyone is so blessed. I am glad that you were able to remove your child from this awful situation and hope that the home-schooling works out well.

    March 5, 2012 at 23:39 | Report abuse | Reply
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