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Thanks to widespread vaccination campaigns across most of the developed world, very few people or their dogs in those areas contract rabies, which is almost always fatal in humans.

But in parts of the world where vaccination rates remain far lower, rabies claims tens of thousands of human lives a year. Fortunately, one such case in China has a silver lining.

As scientists report in the Journal of Venomous Animals and Toxins Including Tropical Diseases, a 25-year-old pregnant woman in Henan province who was infected by a dog she didn't know had rabies gave birth to a healthy, uninfected boy—just before the virus claimed her own life.

Researchers posit that the placenta played a protective role, but they note there were still ample opportunities for the virus to pass to the child, particularly during delivery.

"The prompt administration of vaccines and anti-rabies immunoglobulin to the infant may have also contributed to his survival," they write. The rabies virus has a "well-earned reputation for its brutal ingenuity," Medical Daily notes.

After taking over most any warm-blooded mammal's central nervous system, causing excessive salivation and aggression, it then hides out in the salivary glands, where it provokes its host to bite or scratch another creature and keep the vicious cycle alive.

And while the researchers report that there are only six other documented cases of a pregnant woman with full-blown rabies delivering a baby, five of those six newborns did survive.

Their mothers weren't so fortunate. (This girl became only the third person to survive rabies without the vaccine.)

This article originally appeared on Newser: Rabies Kills a Pregnant Woman; Son Finds Better Fate

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