Vítovec J, Koudela B
Institute of Parasitology, Czechoslovak Academy of Sciences Ceské Budĕjovice.
Vet Parasitol. 1992 Jun;43(1-2):25-36. doi: 10.1016/0304-4017(92)90045-b.
The pathogenesis of intestinal cryptosporidiosis was studied in 52 conventionally reared and 20 gnotobiotically reared piglets by inoculation with different doses of Cryptosporidium parvum oocysts. The prepatent period of C. parvum in both groups of animals were variable, depending on the number of oocysts administered. The patent period of C. parvum in conventionally reared piglets was 8 or 9 days; in gnotobiotic piglets cryptosporidia were found in feces until Day post infection (DPI) 16, when the last piglet was necropsied. Cryptosporidiosis in conventionally reared piglets is a self-limited diarrheal disease associated with morphological changes within the intestine. The most severe lesion was seen in the posterior jejunum and ileum from DPI 3 to DPI 7, and consisted of villous atrophy, crypt hyperplasia and inflammatory infiltration in the lamina propria. In gnotobiotic piglets cryptosporidia induced severe enterocolitis which occurred at least until DPI 16. The characteristics of enteric lesions were similar to those found in conventionally reared piglets. Intestinal cryptosporidiosis in both groups of animals shifted in the course of infection in the caudal direction and terminated in the large intestine. Examination by scanning electron microscope showed that infected absorptive cells had thicker and longer microvilli than those on non-infected cells; neighboring non-infected cells were hypertrophic, bulbously protuberant with minute microvilli with no distinct intercellular borders. Numerous cryptosporidia in the heterotopic glandular epithelium in the submucosa of cecum and colon on DPI 9 and 10 were found. No differences in the location and degree of cryptosporidial infection between colostrum-fed and colostrum-deprived conventionally reared piglets were found. Sow's colostrum does not appear to protect piglets from C. parvum infection. The role of intestinal microflora in the pathogenesis of cryptosporidiosis in piglets is discussed.
通过接种不同剂量的微小隐孢子虫卵囊，对52头常规饲养和20头无菌饲养的仔猪进行了肠道隐孢子虫病发病机制的研究。两组动物中微小隐孢子虫的潜伏期各不相同，这取决于接种的卵囊数量。常规饲养仔猪中微小隐孢子虫的排虫期为8或9天；在无菌饲养仔猪中，直到感染后第16天（最后一头仔猪进行尸检时），粪便中仍可发现隐孢子虫。常规饲养仔猪的隐孢子虫病是一种自限性腹泻疾病，与肠道内的形态学变化有关。在感染后第3天至第7天，空肠后段和回肠出现最严重的病变，包括绒毛萎缩、隐窝增生和固有层炎症浸润。在无菌饲养仔猪中，隐孢子虫引起严重的小肠结肠炎，至少持续到感染后第16天。肠道病变的特征与常规饲养仔猪相似。两组动物的肠道隐孢子虫病在感染过程中都向尾端转移，并在大肠中终止。扫描电子显微镜检查显示，感染的吸收细胞的微绒毛比未感染细胞的更厚更长；相邻的未感染细胞肥大，呈球状突出，有微小的微绒毛，细胞间边界不明显。在感染后第9天和第10天，在盲肠和结肠黏膜下层的异位腺上皮中发现了大量隐孢子虫。初乳喂养和未喂养初乳的常规饲养仔猪在隐孢子虫感染的位置和程度上没有差异。母猪初乳似乎不能保护仔猪免受微小隐孢子虫感染。讨论了肠道微生物群在仔猪隐孢子虫病发病机制中的作用。
