When the anthrax scare hit in the fall of 2001, Karen Becker was among those called in to contain the outbreak. “This beast was already out of the cage, and all we knew was that we had a manipulated, deadlier strain of anthrax. We realized we weren’t going to prevent it, but we could prevent it from going further,” she says. Becker had been working at the Centers for Disease Control at the time, but after the 9/11 attacks her former mentor, D.A. Henderson, who’d coordinated the eradication of smallpox, had been brought in to the U.S. Department of Health and Human Services (HHS) to shore up the nation’s readiness for health emergencies. When anthrax spores appeared in the U.S. mail, Henderson brought in Becker.

Two years later, Becker is a senior health adviser to HHS Secretary Tommy Thompson, collaborating with other public-health officials to strengthen emergency preparedness across the country and abroad. One moment she might be on Capitol Hill talking to Congress; later, she’s meeting with health ministers from other countries or coordinating the emergency plans of such groups as the defense department, the U.S. Food and Drug Administration, and the World Health Organization.

Becker never intended to become a public official. When most of her fellow psychobiology classmates were trotting off to medical school, she chose a path less traveled: vet school. She had spent her teens in rural Minnesota, working on horse farms during the summers. She worked as a vet for twelve years, doing a lot of public health care without realizing it, she says. “Animals are terrific sentinels for disease,” she says, calling it a “no-brainer” that veterinarians are acutely aware of the way epidemics travel because much of their education is herd health.

Becker’s introduction to the human variety of herd health came in 1993, when she won a fellowship to work on health care reform on Capitol Hill. The seed was planted. Becker earned a master’s in public health at Johns Hopkins, where Henderson advised her on bioterrorism issues, then worked in China combating the rise in sexually transmitted diseases and AIDS.

Mother Nature can be the worst terrorist of all, Becker says, offering last year’s SARS outbreak as an example. SARS could have been simmering for years, she says, and in a crowded population like China’s, it can spread rapidly. Chinese health officials “probably didn’t realize they were dealing with a pathogen that was different from the normal respiratory viruses that could be contained within their borders,” she says. Whether disseminated by terrorists or through the overcrowding of human or animal populations, emerging pathogens are the real threat, Becker says. And preparing for one method of dispersal protects against the other. “By strengthening preparedness against bioterrorism,” she says, “we’re also preparing for natural disease outbreaks.”