10 Deadly Agents the CDC Works With

Eight-year-old Precious Reynolds, pictured here at the UC Davis hospital in Sacramento, California, became the sixth person to survive rabies without receiving a vaccine. © Michael Macor/San Francisco Chronicle/San Francisco Chronicle/Corbis

As kids, we used to live in fear of dog bites because, beyond the painful snap and crunch, we knew something far more horrifying waited: rabies shots, 20-some-odd punctures with giant needles, delivered straight to the abdomen. Utterly cringeworthy, true, but little did we know that, next to the alternative, they were a walk in the dog park.

Following an incubation period of typically three to 12 weeks, the first sign of rabies is often a numb or tingly sensation around the bite, growing worse over the days to come. This prodromal or early symptom stage can last 0-10 days before giving way to two to seven days of acute symptoms, beginning with fever, headache, weakness and discomfort. These then progress to such effects as anxiety, confusion, insomnia, hallucinations, partial paralysis, hypersalivation and difficulty swallowing. Once acute symptoms appear, coma and death follow rapidly, usually within a week.

Rabies kills more than 55,000 people annually, mainly in Africa and Asia, but is 100 percent preventable with proper early treatment. As for post-exposure vaccinations, doctors no longer deliver them to the stomach. Typically, victims receive several rabies vaccine shots over four days, spaced out, along with a few doses of human rabies immune globulin, one at the bite site and the rest pumped in intramuscularly at another site distant from it [source: CDC].