最新一項研究發現，養貓的女性更容易患精神疾病、且會有自殺傾向。原因是貓砂中有一種寄生蟲極易被人體感染，然后潛藏于人腦和肌肉細胞內，而這種寄生蟲感染多與精神疾病有關。研究人員稱，這種寄生蟲叫弓形蟲，接觸貓的糞便、食入未烹制熟肉以及未清洗的蔬菜時都有可能感染該寄生蟲。在這項針對超過4.5萬名女性的研究中，研究人員發現，感染弓形蟲的女性自殺的幾率是未感染女性的1.5倍，而且隨著體內弓形蟲抗體的增加，自殺幾率也隨之上升。

　　Women who own cats are more likelyto have mental health problems and commit suicide because they canbe infected by a common parasite that can be caught from catlitter, a study has found。

　　Researchers found women infectedwith the Toxoplasmagondii (T. gondii) parasite, which is spreadthrough contact with cat faeces or eating undercooked meat orunwashed vegetables, are at increased risk of attemptingsuicide。

　　The study involved more than 45,000women in Denmark. About a third of the world’s population isinfected with the parasite, which hides in cells in the brain andmuscles, often without producing symptoms。

　　The infection, which is calledtoxoplasmosis, has been linked to mental illness, such asschizophrenia, and changes in behavior。

　　The study’s senior author DoctorTeodor Postolache, an associate professor of psychiatry at theUniversity of Maryland School of Medicine in the United States,said: “We can’t say with certainty that T. gondii caused the womento try to kill themselves, but we did find a predictive associationbetween the infection and suicide attempts later in life thatwarrants additional studies。

　　“We plan to continue our researchinto this possible connection。”

　　Doctor Albert Reece, vice presidentof medical affairs at the University of Maryland, said: “T. gondiiinfection is a major public health problem around the world, andmany people don’t realize they’re infected。

　　“Dr Postolache is a leading experton suicide neuroimmunology. Suicide is a critically importantmental health issue. About one million people commit suicide andanother 10 million attempt suicide worldwide each year. We hopethat this type of research will one day help us find ways to savemany lives that now end prematurely in suicide。”

　　The study is the largest ever of T.gondii and attempted suicide and the first prospective study todocument suicide attempts that occurred after the infection wasdiscovered。

　　Dr. Postolache’s research team atthe University of Maryland was the first to report a connectionbetween T. gondii and suicidal behavior in 2009. He iscollaborating with researchers in Denmark, Germany and Sweden toconfirm and investigate the mechanism leading to thisassociation。

　　The T. gondii parasite thrives inthe intestines of cats, and it is spread through oocysts passed intheir faeces. All warm-blooded animals can become infected throughingestion of these oocysts. The organism spreads to their brain andmuscles, hiding from the immune system within “cysts” insidecells。

　　Humans can become infected bychanging their infected cats’ litter boxes, eating unwashedvegetables, drinking water from a contaminated source, or morecommonly, by eating undercooked or raw meat that is infested withcysts。

　　Not washing kitchen knives afterpreparing raw meat before handling another food item also can leadto infection. Pregnant women can pass the parasite directly totheir unborn babies and are advised not to change cat litter boxesto avoid possible infection。

　　Babies don’t produce antibodies toT. gondii for three months after they are born, so the antibodiespresent in their blood represented infection in the mothers. Thescientists scoured Danish health registries to determine if any ofthese women later attempted suicide, including cases of violentsuicide attempts which may have involved guns, sharp instrumentsand jumping from high places。

　　The study found that women infectedwith T. gondii were one and a half times more likely to attemptsuicide compared to those who were not infected, and the riskseemed to rise with increasing levels of the T. gondiiantibodies。

　　Dr Postolache noted limitations tothe study, such as the inability to determine the cause of thesuicidal behavior。

　　He added: “T. gondii infection islikely not a random event and it is conceivable that the resultscould be alternatively explained by people with psychiatricdisturbances having a higher risk of becoming T. gondii infectedprior to contact with the health system。”

　　The findings were published onlinein the Archives of General Psychiatry。