While parasites are not all disease causing organisms per se, they all possess varying degrees of pathogenicity, depending upon how the various life cycles of the organism behave within the host.
"Biologically, it doesn't make sense for a parasite to destroy its host," said Lindsay, a parasitologist who specializes in studying the molecular interactions between parasites and hosts. "A parasite doesn't want to cause disease. It just wants to maintain itself. If the parasite kills the host, then it is threatening its own survival in the long run."
In the case of Neospora caninum, sporozoites, a life stage which follows oocysts, spread out throughout the body systems of the host, penetrating intestinal walls in some cases and central nervous system tissues in others.
Humans are not believed to be susceptible to Neospora, Lindsay says, although experimentally infected primates have demonstrated their suitability as host organisms.
Besides domestic and stray dogs, coyotes and foxes are also believed to harbor the organism, Lindsay said.
While the discovery provides sound scientific justification for the new cattle management recommendations, Lindsay says the true value of the work is the foundation it provides for future scientific research.
Those efforts might include work on the development of an immuno-parasitic approach to containing the parasitic disorder, where host animals are challenged to develop an immunological response to the parasites. Lindsay estimates such an approach could take five to ten years to develop.
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Contact: David S. Lindsay
lindsayd@vt.edu
540-231-6302
Virginia Tech
30-Oct-1998