Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/15/2013
Publication Date: 10/1/2013
Citation: Dubey, J.P., Rosenthal, B.M. 2013. Letter to the editor: Identification of Sarcocystis capracanis in cerebrospinal fluid from sheep with neurological disease. Veterinary Parasitology. 197:407-408.
Interpretive Summary: The host range, pathogenesis, and tissue tropism of parasitic species are issues of considerable interest to veterinarians, pathologists, and epidemiologists. Such determinations can be difficult, especially in circumstances where parasites appear in atypical hosts or tissues. In the case of tissue cyst forming coccidia, diagnoses may be aided by a record of case reports and morphological descriptions, spanning several decades, augmented by more recent literature that also make use of ultrastructural and genetic characterization. In isolation, none of these tools provides perfect diagnostic resolution, especially given gaps in the established literature and in light of the realization that biologically distinct taxa may strongly or even perfectly resemble one another in one or more ways. Here, we reexamine several conclusions reached in a written report to highlight steps that can be taken to better ensure that diagnoses rest on adequate support and that research reports contain details necessary for the readership to assess and verify such data.
Technical Abstract: A recent report (Formisano et al., 2013) identified clinical sacrocystosis in 2 adult sheep. The diagnosis relied primarily on characterization of DNA extracted from cerebrospinal fluid (CSF) and paraffin-embedded heart tissue. Parasites identified as merozoites were identified in CSF smears stained with Giemsa. The infection was attributed to Sarcocystis capracanis, a species otherwise known to cycle through goats (Capra hircus) and dogs (Canis familiaris). We wish to point out several aspects of this work which we fear compromise the validity of that conclusion, motivated by an interest in highlighting for the research and diagnostic communities the care which must be taken before reaching such diagnostic conclusions.