Centre for Parasitology and Disease Research, School of Environment and Life Sciences, University of Salford, Salford M5 4WT, UK.
Parasitology. 2011 Aug;138(9):1117-23. doi: 10.1017/S0031182011000904. Epub 2011 Jul 15.
The protozoan parasite Toxoplasma gondii is prevalent worldwide and can infect a remarkably wide range of hosts despite felids being the only definitive host. As cats play a major role in transmission to secondary mammalian hosts, the interaction between cats and these hosts should be a major factor determining final prevalence in the secondary host. This study investigates the prevalence of T. gondii in a natural population of Apodemus sylvaticus collected from an area with low cat density (<2·5 cats/km2). A surprisingly high prevalence of 40·78% (95% CI: 34·07%-47·79%) was observed despite this. A comparable level of prevalence was observed in a previously published study using the same approaches where a prevalence of 59% (95% CI: 50·13%-67·87%) was observed in a natural population of Mus domesticus from an area with high cat density (>500 cats/km2). Detection of infected foetuses from pregnant dams in both populations suggests that congenital transmission may enable persistence of infection in the absence of cats. The prevalences of the related parasite, Neospora caninum were found to be low in both populations (A. sylvaticus: 3·39% (95% CI: 0·12%-6·66%); M. domesticus: 3·08% (95% CI: 0·11%-6·05%)). These results suggest that cat density may have a lower than expected effect on final prevalence in these ecosystems.
刚地弓形虫是一种原生动物寄生虫，在全世界广泛流行，尽管猫科动物是其唯一的终末宿主，但它可以感染范围广泛的宿主。由于猫在传播给次级哺乳动物宿主方面起着主要作用，猫与这些宿主之间的相互作用应该是决定次级宿主最终流行率的主要因素。本研究调查了从猫密度较低的地区（<2.5 只/平方公里）采集的野生小家鼠自然种群中刚地弓形虫的流行率。尽管如此，仍观察到惊人的高流行率为 40.78%（95%CI：34.07%-47.79%）。在之前使用相同方法在猫密度较高的地区（>500 只/平方公里）采集的野生家鼠自然种群中进行的一项研究中观察到了可比水平的流行率，其流行率为 59%（95%CI：50.13%-67.87%）。在两个种群中从怀孕的母鼠中检测到感染的胎儿表明，先天性传播可能使感染在没有猫的情况下得以持续存在。在两个种群中，相关寄生虫新孢子虫的流行率均较低（野生小家鼠：3.39%（95%CI：0.12%-6.66%）；家鼠：3.08%（95%CI：0.11%-6.05%））。这些结果表明，在这些生态系统中，猫密度对最终流行率的影响可能低于预期。
