"It's been a rough flu season this winter in the United States and Europe, but it could be worse. A lot worse," science writer Carl Zimmer states in National Geographic's "Phenomena: The Loom" blog. In other parts of the world, including Egypt, India and Cambodia, the H5N1 avian influenza strain is "lurking," and according to official estimates, the disease has a case-fatality rate of 59 percent, he notes, adding that "may be a serious overestimate." Zimmerman continues, "[E]ven if the true rate was only half as high, H5N1 would not be a virus you'd want to cross paths with," and notes that the Spanish flu outbreak of 1918 had a case-fatality rate of about two percent and killed 50 to 100 million people worldwide.