Experimentally Induced Clinical Cystoisospora canis Coccidiosis in Dogs with Prior Natural Patent Cystoisospora ohioensis-like or C. canis Infections

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Date
2013-10
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American Society of Parasitology
Abstract

Diarrhea caused by intestinal coccidia (Cystoisospora species) is a common problem in pet dogs and in dogs in animal shelters. Cystoisospora canis has the largest oocysts of the 4 named species of coccidia infecting dogs. The present study examined an isolate of C. canis obtained from a dog from Sa o Paulo, SP, Brazil. Oocysts sporulated within 2 days at room temperature, and 20 sporulated oocysts were measured at 37.6 by 28.6 lm (range 35-42 by 26-31 lm). Most sporulated oocysts contained 2 sporocysts, each with 4 sporozoites, although a few (, 1%) were Caryospora-like and contained 1 sporocyst with 8 sporozoites. Two experiments using a total of 11 female 6-wk-old beagles were conducted to determine the pathogenicity of oral infection with 5 3 10 4 sporulated oocysts of this isolate of C. canis. Five of the 11 dogs had natural infections with Cystoisospora ohioensis-like (n 4) or C. canis (n 1) species prior to the predicted patent period of 9-10 days. Ten of the dogs developed diarrhea with occasional blood, and 3 dogs were affected to the extent that clinical treatment for coccidiosis using sulfadimethoxine was recommended. Dog CRU had a natural C. canis infection and did not develop clinical disease after oral infection with C. canis oocysts. This dog had a prepatent period of 9 days and a patent period of 3 days, corresponding to experimental infection with the new isolate of C. canis. It excreted fewer C. canis oocysts than did the other dogs. The 4 dogs with natural C. ohioensis-like infection all developed clinical disease, and 1 required treatment. The prepatent period was 9-10 days, and the patent period was 10-11 days in these dogs. All 6 dogs not naturally infected with Cystoisospora developed clinical disease, and 2 required treatment. The prepatent period was 9-10 days, and the patent period was 8-12 days. The present study confirms that C. canis is a primary pathogen for young dogs. It demonstrates that prior infection with C. canis but not C. ohioensis-like coccidia confers some resistance to clinical disases and a decrease in oocyst production in dogs challenged with C. canis.

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Keywords
phylogenetic analysis, isospora-canis, oocysts, sporogony, nemeseri, field, parasitology
Citation
Alice E. Houk, Thomas O'Connor, Hilda F. J. Pena, Solange Maria Gennari, Anne M. Zajac, and David S. Lindsay (2013). "Experimentally Induced Clinical Cystoisospora canis Coccidiosis in Dogs with Prior Natural Patent Cystoisospora ohioensis-like or C. canis Infections," Journal of Parasitology, Vol. 99, No. 5, pp. 892-895. doi: http://dx.doi.org/10.1645/13-197.1