Back in 1994, a deadly virus swept through Serengeti National park, killing 30 percent of all wild lions in the region. The cause was later revealed to be canine distemper - a shocking revelation as it had long been suspected that cats couldn't contract the virus. Now, new research has found that not only did dogs likely bring the virus to these cats, but it was then spread further by another unidentified species.

That's at least according to a study recently published in the Proceedings of the National Academy of Sciences (PNAS), which details how an international team of researchers has found that while the initial 1994 infection of lions came from dogs, a subsequent spike in infections clearly did not. This suggests another species, one that likely roams, could still be carrying the disease and may potentially spread it once more.

This was determined after a large team of biologists set out to investigate the Serengeti distemper outbreak, analyzing serelogical (blood, urine, etc.) data obtained from lions in the park between the years 1984 to 2014, and domestic dog samples collected between 1992 and 2012.

True to its name, canine distemper virus (CDV) was first detected in dogs in the early 1900s, and has since been associated with members of the canaidae (fox, wolf, coyote), procyonidae (panda, raccoon, etc.), and mustelidae (ferret, badger, otter) families. It causes gastrointestinal and respiratory trouble, and leads to high fever, swollen eyes and vomiting. It can also help facilitate deadly bacterial infections of the neurosystem, which always proves fatal.

While the fact that infected dogs caused the 1994 outbreak wasn't exactly a surprise, the researchers were still stunned to see that another species played a part. This is a worrisome discovery because, while domestic dog vaccination programs were subsequently implemented to curb the spread of the disease by 2000, this other species may continue to have CDV looming in the background.

The consequence may be a resurgence of the virus at any time, threatening lion populations already at risk by encroaching human populations.

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