Cats may be spreading brain
cancer to their owners, scientists warned. They have linked a
parasite that breeds in cats' stomachs with brain tumours in people.
The
parasite in the frame - Toxoplasma gondii, which infects up to 34 percent of Britons, has a
complicated lifecycle but can only breed inside cats, which then pass their
microscopic eggs, spreading the infection.
Pregnant women are already advised not to empty cat
litter trays, as the
parasite can be fatal to
unborn babies, and now it seems the health risks may extend to other people.
French scientists collected global data on brain cancers in men and women and compared it with figures on T. gondii
infection rates.
This showed brain
cancer rates to be highest in countries where the
parasite was most
prevalent - even when other factors such as
income were taken into account.
The scientists, led by Frederic Thomas, from the CNRS
researchinstitute in Montpellier, said: "We feel our results are
sufficiently strong to propose that T. gondii potentially increases the risk of brain
cancer in humans."
There is also other evidence that T. gondii has effects on the brain leading to changes in behaviour.
Infected rats are known to lose their fear of cats, making it more likely that they will be killed and eaten. The
parasite may also sway human behaviour, with
research suggesting it turns men into aggressive,
jealous , while transforming women into "sex kittens".
Other
research has
pointed to a strong link between T. gondii and schizophrenia.
Chief causes of
infection in humans are consuming undercooked meat, especially lamb, pork and venison, and ingesting water, soil or anything else contaminated by cat faeces.
The scientists behind the latest study acknowledged that they hadn't proved that cats are spreading brain
cancer but added: "Clearly, further
research is necessary to determine the proximate links between T. gondii and different types of brain tumours."
"Establishing a link between T. gondii and brain cancers could open the door to
potential means to reduce
cancer risk."
据英国《每日邮报》27日报道,科学家发现猫胃里的寄生虫与人类脑癌有直接关系,并发出提醒猫可能会使其主人染上脑癌。
这种寄生虫叫做弓形虫,感染了将近34%的英国人,该寄生虫生活周期虽然复杂,但只繁殖在猫体内,之后猫就有可能将极细小的虫卵传播给人类,造成感染。
之前,科学家就建议怀孕的妇女不要去清理猫沙,因为弓形虫对胎儿有致命的影响,但现在看来,它们也可能成为其他人的安全隐患。
法国科学家们收集了全球脑癌患者的数据,并将其与弓形虫感染率进行比较。
结果证明,即使将诸如收入等因素考虑在内,脑癌患病率高的地区也是弓形虫传染的高发区。
这项研究由来自蒙彼利埃法国科学研究中心弗雷德里克•托马斯领导。科学家们说:"我们认为此结果可以充分证明弓形虫能潜在地增加人脑患癌几率。"
另有证据表明,弓形虫对于脑部的影响还会导致行为的变化。
被感染的老鼠会对猫失去恐惧感,从而更容易被猫捕食。研究证明,该寄生虫还会影响人类行为,使男人变得更好斗,易嫉妒,让女人变得更性感。
另外也有研究证明弓形虫和精神分裂症之间存在密切联系。
导致人类感染弓形寄生虫的主要原因是食用未煮熟的肉,特别是小羊羔肉、猪肉和野味。同时,吞下被猫排泄物污染的水、沙子等任何东西都有可能引起感染。
提出这项最新研究的科学家承认,他们还无法证明脑癌就是通过猫传播给人类的,但是他们补充说:"显然,要确定弓形寄生虫和其他不同类型的脑肿瘤之间的相近性联系,还需要更多的研究。"
"确立弓形寄生虫和脑癌的联系为潜在地降低患癌几率提供了机会。"