Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, USA.
Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, USA.
Int J Parasitol. 2019 Feb;49(2):145-151. doi: 10.1016/j.ijpara.2018.06.006. Epub 2018 Oct 24.
The incidence of babesiosis, Lyme disease and other tick-borne diseases has increased steadily in Europe and North America during the last five decades. Babesia microti is transmitted by species of Ixodes, the same ticks that transmit the Lyme disease-causing spirochete, Borrelia burgdorferi. B. microti can also be transmitted through transfusion of blood products and is the most common transfusion-transmitted infection in the U.S.A. Ixodes ticks are commonly infected with both B. microti and B. burgdorferi, and are competent vectors for transmitting them together into hosts. Few studies have examined the effects of coinfections on humans and they had somewhat contradictory results. One study linked coinfection with B. microti to a greater number of symptoms of overall disease in patients, while another report indicated that B. burgdorferi infection either did not affect babesiosis symptoms or decreased its severity. Mouse models of infection that manifest pathological effects similar to those observed in human babesiosis and Lyme disease offer a unique opportunity to thoroughly investigate the effects of coinfection on the host. Lyme disease has been studied using the susceptible C3H mouse infection model, which can also be used to examine B. microti infection to understand pathological mechanisms of human diseases, both during a single infection and during coinfections. We observed that high B. microti parasitaemia leads to low haemoglobin levels in infected mice, reflecting the anaemia observed in human babesiosis. Similar to humans, B. microti coinfection appears to enhance the severity of Lyme disease-like symptoms in mice. Coinfected mice have lower peak B. microti parasitaemia compared to mice infected with B. microti alone, which may reflect attenuation of babesiosis symptoms reported in some human coinfections. These findings suggest that B. burgdorferi coinfection attenuates parasite growth while B. microti presence exacerbates Lyme disease-like symptoms in mice.
在过去的五十年中，欧洲和北美的巴贝虫病、莱姆病和其他蜱传疾病的发病率稳步上升。微小巴贝斯虫通过伊蚊属的物种传播，这些蜱同样传播导致莱姆病的螺旋体，伯氏疏螺旋体。微小巴贝斯虫也可以通过输血传播，是美国最常见的输血传播感染。伊蚊属的蜱通常同时感染微小巴贝斯虫和伯氏疏螺旋体，并且是将它们一起传播给宿主的有效载体。很少有研究检查过合并感染对人类的影响，并且它们的结果有些矛盾。一项研究将微小巴贝斯虫的合并感染与患者总体疾病症状的增加联系起来，而另一项报告表明，伯氏疏螺旋体感染既不会影响巴贝斯虫病的症状，也不会减轻其严重程度。在感染后表现出与人类巴贝斯虫病和莱姆病相似的病理效应的感染小鼠模型为深入研究合并感染对宿主的影响提供了独特的机会。莱姆病已经使用易感 C3H 小鼠感染模型进行了研究，该模型也可用于检查微小巴贝斯虫感染，以了解人类疾病的病理机制，包括单一感染和合并感染。我们观察到，高微小巴贝斯虫寄生虫血症导致感染小鼠的血红蛋白水平降低，反映了人类巴贝斯虫病中观察到的贫血。与人类相似，微小巴贝斯虫的合并感染似乎会加重小鼠莱姆病样症状的严重程度。与单独感染微小巴贝斯虫的小鼠相比，合并感染的小鼠的微小巴贝斯虫寄生虫血症峰值较低，这可能反映了一些人类合并感染中报告的巴贝斯虫病症状的减轻。这些发现表明，伯氏疏螺旋体的合并感染会削弱寄生虫的生长，而微小巴贝斯虫的存在会加重小鼠的莱姆病样症状。
