Cats and dogs: Of parasites and viruses

A pair of unrelated studies sheds some light on a parasite spread by cats, and a canine virus that could help understand the human virus hepatitis C.

Researchers at the University of Illinois studied the prevalence of the parasite Toxoplasma gondii within a large park in central Illinois. T. gondii reproduces only in cats, but it is the cause of toxoplasmosis, which can have serious or deadly effects on other mammals including humans, most notably the fetuses of pregnant women.

Using several detection methods, the scientists found dozens of feral cats in the area, and trapped 18 of them. They found that one-third of the cats were infected with T. gondii, and large numbers of other wild animals in the park that were tested also carried the parasite.

They found that animals with large home-ranges had an overall higher prevalence of T. gondii antibody. Small-home-range animals were more likely to have the antibody if they lived in an area with a lot of cats.

"Small-home-range mammals are an essential part of T. gondii-antibody prevalence studies and can be used as sentinels for risk of disease exposure to humans and wildlife in natural areas," the authors wrote. "This study improves our understanding of ecologic drivers behind the occurrence of spatial variation of T. gondii within a natural area."

The study, "Prevalence of antibody to Toxoplasma gondii in terrestrial wildlife in a natural area," was published in the Journal of Wildlife Diseases.

Canine virus related to hepatitis C

Researchers from a variety of institutions have published a paper on a canine homolog of the human hepatitis C virus (HCV). In the study, the scientific team show that canine hepacivirus (CHV) is "the most genetically similar animal virus homolog of HCV."

According to the study, the canine and the human version of this virus diverged between 500 and 1,000 years ago, long after the dog was domesticated. The researchers hope that the identification of this canine virus as related to HCV will help provide insight into the virus’ origin and evolution, and eventually help to prevent and treat diseases associated with it.

The paper, "Characterization of a canine homolog of hepatitis C virus," was published in the Proceedings of the National Academy of Sciences.

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