( CNN ) -- Cat poop could be a `` vast and underappreciated '' public health problem , according to Drs . E. Fuller Torrey and Robert H. Yolken . The pair on Tuesday published a paper on the dangers of Toxoplasma oocysts , which are found in cat poop , in the journal Trends in Parasitology . In the journal article , Torrey and Yolken call for better control of the feral cat population and more research on the parasites . In the meantime , CNN asked the doctors how we can keep our families safe . Torrey and Yolken responded to the questions via e-mail . CNN : We 've heard that cat poop can be dangerous for pregnant women . Should other people be wary , too ? Drs . E. Fuller Torrey and Robert H. Yolken : It is true that some cat poop contains Toxoplasma gondii , a parasite for which cats and other felines are the definitive host . This parasite can affect the fetus if a woman becomes infected while pregnant . That is why pregnant women are warned against changing cat litter . It 's also well-known that Toxoplasma gondii can cause major brain infections in individuals with AIDS and other conditions associated with immune deficiency . Chain of cat feces can harm humans , sea otters . So what 's new ? Recent studies suggest that individuals with disorders such as schizophrenia , obsessive-compulsive disorder , rheumatoid arthritis or brain tumors are more likely to have Toxoplasma gondii antibodies than other people . There are also suggestions that Toxoplasma gondii can affect memory and other cognitive function in people who are not otherwise ill . In no way have we established Toxoplasma gondii as a cause of these disorders , but it has led us to rethink the possible risks of cat poop . CNN : How big of a risk are we talking about ? Torrey and Yolken : There are an estimated 82 million owned cats and another 25 million to 60 million feral cats in the United States , and their numbers have increased markedly in recent years . Based on studies done in California , it is estimated that these cats deposit 1.2 million tons of cat poop into the environment each year . At any given time , approximately 1 % of cats are infected with Toxoplasma gondii . The infective form of Toxoplasma gondii deposited in cat poop are called oocysts ; a single infected cat can deposit millions of oocysts , each of which may survive in moist soil for 18 months or longer . It 's thought that it only takes one oocyst to infect a human , which is concerning . CNN : So what can people do to protect themselves ? Torrey and Yolken : It is important to note that cats that are always kept indoors are usually not a problem . Almost all cats that become infected , and thus deposit infective oocysts , are outdoor cats . Keep in mind cats are no respecters of property lines so a neighbor 's cat could deposit Toxoplasma gondii oocysts in your garden or children 's play areas . Weird science : Kitty litter increases risk of suicide ? To stay safe , follow these suggestions : . • Cat litter should be properly disposed of in the garbage , not flushed down the toilet where it can enter rivers and lakes . • Children 's sandboxes and play areas should be covered when not in use . Cats selectively relieve themselves in areas with loose soil or sand . In the studies we reviewed , we found very high concentrations of Toxoplasma gondii oocysts in these areas . If a sandbox has not been covered , the sand should be replaced and then kept covered . • Gardeners should wear gloves since gardens are another favorite place for cats to relieve themselves . One study reported that gardeners may have as many as 100 oocysts in dirt under their fingernails . • Vegetables from gardens should be thoroughly washed . More on toxoplasmosis .
Some cat poop contains the parasite Toxoplasma gondii . New studies suggest it can affect memory , cognitive function in people who are not ill. Doctors : http://bit.ly/2kfq4wJ