澳大拉西亚有袋动物中弓形虫感染的流行病学、临床疾病和遗传多样性的最新研究进展。
Recent aspects on epidemiology, clinical disease, and genetic diversity of Toxoplasma gondii infections in Australasian marsupials.
机构信息
United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Building 1001, Beltsville, MD, 20705-2350, USA.
Department of Microbiology, University of Tennessee, Knoxville, TN, 37996-0845, USA.
出版信息
Parasit Vectors. 2021 Jun 5;14(1):301. doi: 10.1186/s13071-021-04793-4.
BACKGROUND
Toxoplasma gondii infections are common in humans and animals worldwide. Among all intermediate hosts of T. gondii, captive marsupials from Australia and New Zealand are highly susceptible to clinical toxoplasmosis. However, most free-range marsupials establish chronic T. gondii infection. Infected marsupial meat may serve as a source of T. gondii infection for humans. Differences in mortality patterns in different species of kangaroos and other marsupials are not fully understood. Lifestyle, habitat, and the genotype of T. gondii are predicted to be risk factors. For example, koalas are rarely exposed to T. gondii because they live on treetops whereas wallabies on land are frequently exposed to infection.
METHODS
The present review summarizes worldwide information on the prevalence of clinical and subclinical infections, epidemiology, and genetic diversity of T. gondii infecting Australasian marsupials in their native habitat and among exported animals over the past decade. The role of genetic types of T. gondii and clinical disease is discussed.
RESULTS
Fatal toxoplasmosis has been diagnosed in captive Australasian marsupials in Argentina, Chile, China, Germany, Hungary, Japan, Spain, Turkey, and the USA. Most deaths occurred because of disseminated toxoplasmosis. Genetic characterization of T. gondii strains isolated from fatal marsupial infections identified Type III as well as atypical, nonclonal genotypes. Fatal toxoplasmosis was also diagnosed in free-ranging wombats (Vombatus ursinus) in Australia. Genetic characterization of DNA amplified directly from host tissues of subclinical culled kangaroos at slaughter identified many mixed-strain infections with both atypical and recombinant genotypes of T. gondii.
CONCLUSIONS
Most Australasian marsupials in their native land, Australia and New Zealand, have high prevalence of T. gondii, and kangaroo meat can be a source of infection for humans if consumed uncooked/undercooked. The genotypes prevalent in kangaroos in Australia and New Zealand were genetically distinct from those isolated or genotyped from most macropods in the USA and other countries. Thus, clinical toxoplasmosis in marsupials imported from Australia is most likely to occur from infections acquired after importation.
背景
刚地弓形虫感染在全球范围内的人类和动物中很常见。在所有刚地弓形虫的中间宿主中，来自澳大利亚和新西兰的圈养有袋动物对临床弓形虫病高度易感。然而，大多数自由放养的有袋动物会建立慢性刚地弓形虫感染。受感染的有袋动物肉可能成为人类感染刚地弓形虫的来源。不同袋鼠和其他有袋动物物种的死亡率模式尚不完全清楚。生活方式、栖息地和刚地弓形虫的基因型被预测为危险因素。例如，考拉很少接触刚地弓形虫，因为它们生活在树梢上，而土地上的沙袋鼠则经常受到感染。
方法
本综述总结了过去十年中在澳大利亚本土栖息地和出口动物中，全世界关于临床和亚临床感染的流行率、流行病学和刚地弓形虫遗传多样性的信息。讨论了刚地弓形虫基因型和临床疾病的作用。
结果
在阿根廷、智利、中国、德国、匈牙利、日本、西班牙、土耳其和美国的圈养澳大利亚有袋动物中已诊断出致命的弓形体病。大多数死亡是由于播散性弓形体病引起的。从致命的有袋动物感染中分离出的刚地弓形虫株的遗传特征鉴定出了 III 型以及非典型、非克隆基因型。在澳大利亚的自由放养袋熊（Vombatus ursinus）中也诊断出致命的弓形体病。从屠宰场宰杀的亚临床淘汰袋鼠的宿主组织中直接扩增 DNA 的遗传特征鉴定出了许多混合感染，其中既有非典型基因型也有重组基因型的刚地弓形虫。
结论
在澳大利亚和新西兰本土的大多数澳大利亚有袋动物中，刚地弓形虫的流行率很高，如果食用未煮熟/未煮熟的袋鼠肉，可能会成为人类感染的来源。澳大利亚和新西兰的袋鼠中流行的基因型与从美国和其他国家的大多数有袋目动物中分离或基因分型的基因型在遗传上有明显区别。因此，从澳大利亚进口的有袋动物的临床弓形体病最有可能是在进口后获得的感染引起的。
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