Pathogenicity of Isospora ohioensis infection in dogs
Dubey, J.P.
Journal of the American Veterinary Medical Association 173(2): 192-197
1978
ISSN/ISBN: 0003-1488 PMID: 681223 Document Number: 137956
Six 7-day-old puppies were infected with sporulated oocysts of I. ohioensis (106 by mouth) and four 17-day-old puppies were infected with tissue from mice inoculated with oocysts (5 X 105 by mouth) 17 days before. Puppies were killed at intervals up to 120 hours after infection and their intestines were divided into 1 cm sections for histological examination. In oocyst-infected puppies diarrhoea and intestinal lesions occurred in puppies killed at 96, 114 and 120 but not at 16, 48 and 72 hours after infection. In mouse tissue-infected puppies diarrhoea and lesions occurred at 72 and 96 but not at 24 and 48 hours. The main lesions were necrosis and desquamation of the tips of the villi. Other lesions were atrophy of the villi and cryptitis in ileum and caecum. In six further experiments puppies of different ages (6 to 384 days) were infected with 105 or 106 oocysts or with tissue from mice infected with the same number of oocysts. Some puppies were re-inoculated 6 to 45 days after the first inoculations. All of 13 weaned puppies remained clinically normal. The patent periods (oocyst shedding) were longer in 6 to 10-day-old puppies (3 to 5 weeks) than in 40 to 384-day-old puppies (1 to 2 weeks). Puppies over 40 days old acquired immunity, which lasted for one to two months, within one week of infection.