Graczyk T K, Cranfield M R
Department of Molecular Microbiology and Immunology, School of Hygiene and Public Health, Johns Hopkins University, Baltimore, MD 21205, USA.
Vet Res. 1998 Mar-Apr;29(2):187-95.
Groups of four to five, 3-month-old rat snakes (Elaphe obsoleta) were separately gastrically inoculated with 2.0 x 10(6) viable oocysts of Cryptosporidium muris (mice and calves), C. muris-like (Bactrian camels), C. wrairi (guinea pigs), C. baileyi (chickens), C. meleagridis (turkeys), Cryptosporidium sp. (turtles, tortoises, chameleons and lizards) and C. serpentis from clinically (fatal case) and subclinically infected snakes. None of the snakes inoculated with oocysts originating from homothermous vertebrates developed infection as determined by histology and serology, whereas all snakes challenged with reptilian oocyst isolates were infected with Cryptosporidium on weeks 6 and 10 post-inoculation (PI). One week 10 PI, the snakes displayed mild to serve, multifocal to widespread, thinning and disorganization of gastric epithelium and nine out of twelve snakes infected by oocysts originating from reptiles other than snakes displayed severe gastric hyperplasia. Three out of ten snakes infected oocysts originating from snakes had ELISA-detectable Cryptosporidium-specific antibody (Ab) titers on week 6 PI; all snakes were Cryptosporidium-seroconverted on week 10 PI and their serum Ab titer significantly increased. The study demonstrated that Cryptosporidium infections in snakes maintained on the diet of rodents or birds cannot be initiated via ingestion of an infected food item; however, snakes can void ingested oocysts. Lack of host specificity among reptiles to this pathogen, demonstrated for the first time in the present study, indicates that snake-attributed C. serpentis is not distinct from Cryptosporidium sp. infecting reptiles other than snakes, and that clinical manifestations and virulence of Cryptosporidium in snakes in modulated by the species of the host. Housing of snakes with other reptiles can enhance transmission of Cryptosporidium to snakes, and therefore should be avoided.
将4至5条3月龄的鼠蛇（锦蛇）分为一组，分别经胃接种2.0×10⁶个来自小鼠和小牛的微小隐孢子虫、双峰驼的类微小隐孢子虫、豚鼠的瓦氏隐孢子虫、鸡的贝氏隐孢子虫、火鸡的火鸡隐孢子虫、龟、陆龟、变色龙和蜥蜴的隐孢子虫属以及临床（致死病例）和亚临床感染蛇的蛇隐孢子虫的活卵囊。经组织学和血清学检测，接种来自恒温脊椎动物卵囊的蛇均未发生感染，而所有用爬行动物卵囊分离株攻击的蛇在接种后第6周和第10周均感染了隐孢子虫。接种后第10周，蛇表现出轻度至重度、多灶性至广泛性的胃上皮变薄和紊乱，12条被来自蛇以外爬行动物的卵囊感染的蛇中有9条表现出严重的胃增生。10条接种来自蛇的卵囊的蛇中有3条在接种后第6周ELISA检测到隐孢子虫特异性抗体（Ab）滴度；所有蛇在接种后第10周均发生隐孢子虫血清转化，其血清Ab滴度显著升高。该研究表明，以啮齿动物或鸟类为食的蛇不能通过摄入受感染的食物引发隐孢子虫感染；然而，蛇可以排出摄入的卵囊。本研究首次证明爬行动物对该病原体缺乏宿主特异性，这表明蛇源性蛇隐孢子虫与感染蛇以外爬行动物的隐孢子虫属没有区别，并且蛇中隐孢子虫的临床表现和毒力受宿主物种的调节。将蛇与其他爬行动物饲养在一起会增加隐孢子虫向蛇的传播，因此应避免。
