8月22日，《生物學(xué)快報(bào)》（Biology Letters）在線報(bào)道了一個(gè)國際研究團(tuán)隊(duì)的發(fā)現(xiàn)，擁有貓的女性并沒有比不養(yǎng)貓的受調(diào)查者更容易患上腦癌,。
貓的排泄物中含有一種被稱為弓形蟲的單細(xì)胞寄生蟲?？茖W(xué)家們發(fā)現(xiàn),，人類弓形蟲感染率較高的國家，其腦癌的發(fā)生率也相對較高,。
不過,，這項(xiàng)發(fā)現(xiàn)具有爭議性，而且很多科學(xué)家認(rèn)為貓和腦癌之間的關(guān)聯(lián)很微弱,。
現(xiàn)在,，另一個(gè)團(tuán)隊(duì)的研究人員相信，他們已經(jīng)解決了這個(gè)問題,。
科學(xué)家們調(diào)查了一個(gè)超過60萬人的年齡均在50歲及以上的英國女性群體,，并追蹤了在平均3年的時(shí)間里有多少女性患上了腦腫瘤。
這些女性中,，有18%的人,，即超過10萬人擁有至少一只貓,。但是，那些養(yǎng)貓的女性并沒有比不養(yǎng)貓的受調(diào)查者更容易患上腦癌,，盡管據(jù)推測前者接觸弓形蟲的風(fēng)險(xiǎn)可能要大,。
所以，下一次當(dāng)有人刮壞了你的家具時(shí),，可以怪罪到貓的頭上,，不過涉及到腦癌時(shí)，還是把矛頭指向別的地方吧,。（生物谷Bioon.com）
doi:10.1098/rsbl.2012.0625
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Cat ownership is neither a strong predictor of Toxoplamsa gondii infection nor a risk factor for brain cancer
Marion Vittecoq1,2, Kevin D. Lafferty3, Eric Elguero1, Jacques Brodeur4, Michel Gauthier-Clerc2, Dorothée Missé1, Benjamin Roche1,5 and Frédéric Thomas1,6,*
Using a dataset including 37 countries, we recently reported a positive correlation between the national seroprevalence of the protozoan parasite Toxoplasma gondii and the national incidence of brain cancer [1]. We further established the significance of this association in a second paper showing that in France, regional mortality rates owing to brain cancer correlated positively with the local seroprevalence of T. gondii [2]. These results do not demonstrate causation but suggest that T. gondii should be investigated further as a possible oncogenic pathogen of humans. Benson et al. [3] used data from a large UK prospective cohort of middle-aged women among whom 18 per cent owned at least one cat. Comparing brain cancer incidence in women living with a cat or without any pet, they found no correlation between cat ownership and brain cancer. This is an important finding because the popular press is drawn to the headline that pet cats are a health risk to their owners. Our disagreement with Benson et al. is that their findings do not inform how T. gondii is linked to brain cancer, which was the main finding of our research. Although cats are a necessary part of the life cycle of T. gondii, multiple studies have shown that cat ownership is not a strong predictor of risk of T. gondii infection [4,5]. Contact with oocysts from cat faeces can occur through contaminated soil or vegetables [6]. Contact with contaminated soil (combined with poor hygiene) and eating unwashed vegetables are significant risk factors [6]. In addition, undercooked meat consumption has been identified as the chief risk factor for human toxoplasmosis in a number of European countries, including the UK ([7]; see [6] for a review). Thus, cat ownership is not a good proxy of the probability of being infected by T. gondii, either through oocysts originating from cats or through T. gondii asexual stages. So, while cats are a key host for T. gondii and T. gondii seems to be a risk factor for brain cancer, cat ownership is not necessarily a significant risk factor for brain cancer, at least not unless other risk factors are accounted for statistically. To conclude, the study of Benson et al. should be reassuring to cat owners, but it does not test whether T. gondii affects risks of brain cancer. Clearly, what is now needed to assess the role of T. gondii in brain cancer risk are studies that compare the seroprevalence of T. gondii in individuals with brain cancer with matched controls.
