Graczyk T K, Fayer R, Cranfield M R
Department of Molecular Microbiology and Immunology, School of Hygiene and Public Health, Johns Hopkins University, Baltimore, Maryland 21205, USA.
J Parasitol. 1996 Oct;82(5):748-51.
A recent report suggested that an isolate of Cryptosporidium parvum had established infections in fish, amphibians, and reptiles and raises concern that animals other than mammals might be a potential source of waterborne Cryptosporidium oocysts. To test this possibility, viable C. parvum oocysts, infectious for neonatal BALB/c mice, were delivered by gastric intubation to bluegill sunfish, poison-dart frogs, African clawed frogs, bearded dragon lizards, and corn snakes. Histological sections of the stomach, jejunum, ileum, and cloaca prepared from tissues collected on days 7 and 14 postinoculation (PI) were negative for Cryptosporidium developmental stages. However, inoculum-derived oocysts were detectable by fluorescein-labeled monoclonal antibody in feces of inoculated animals from day 1 to day 12 PI in fish and frogs, and up to day 14 PI in lizards. Snakes did not defecate for 14 days PI. Impression smears taken at necropsy on days 7 and 14 PI revealed C. parvum oocysts in the lumen of the cloaca of 2 fish and 1 lizard on day 7 PI only. Because tissue stages of the pathogen were not found, it appears that C. parvum was not heterologously transmitted to lower vertebrates. Under certain circumstances, however, such as after the ingestion of C. parvum-infected prey, lower vertebrates may disseminate C. parvum oocysts in the environment.
最近的一份报告表明，一种微小隐孢子虫分离株已在鱼类、两栖动物和爬行动物中建立感染，这引发了人们对除哺乳动物以外的动物可能是水源性隐孢子虫卵囊潜在来源的担忧。为了验证这种可能性，将对新生BALB/c小鼠具有感染性的活微小隐孢子虫卵囊通过胃插管接种给蓝鳃太阳鱼、箭毒蛙、非洲爪蟾、鬃狮蜥和玉米蛇。对接种后第7天和第14天收集的组织制备的胃、空肠、回肠和泄殖腔的组织切片进行微小隐孢子虫发育阶段检测，结果均为阴性。然而，在接种后的第1天至第12天，在鱼类和青蛙的粪便中可通过荧光素标记的单克隆抗体检测到接种源的卵囊，在蜥蜴中可检测到第14天。在接种后的14天内，蛇没有排便。仅在接种后第7天的尸检中，对2条鱼和1只蜥蜴泄殖腔腔内容物进行的压片涂片显示存在微小隐孢子虫卵囊。由于未发现病原体组织阶段，似乎微小隐孢子虫没有异源传播给低等脊椎动物。然而，在某些情况下，例如在摄入感染微小隐孢子虫的猎物后，低等脊椎动物可能会在环境中传播微小隐孢子虫卵囊。
