On June 26 my daughter Sophia picked up the phone. It was her friend Kara McGowan. "We all need to get rabies shots," Kara said. It was not the typical coda to a sleepover, with the caller saying something like: "I found one of your socks under my bed."
Three days earlier Sophia and another friend, Emily, had a slumber party at Kara's house to mark their completion of seventh grade. The next day, after their guests had left, the McGowans spotted a bat fluttering between bedrooms on the upper floor of their suburban New York City home. Several hours later, they spied it again in the bedroom where the girls had slept. A local animal control officer outfitted with leather gloves and a coffee can failed to capture the bat, which meant it couldn't be tested for the disease.
Each of the girls' doctors, as well as one from Kara's and Emily's camp, said they should get what is known as post-exposure prophylaxis (PEP) for rabies. It's a series of five vaccine shots over the course of 28 days, plus additional jabs of rabies immune globulin on the day vaccination begins. The rationale: A bat with tiny, razor-sharp teeth could nip the girls without waking them or leaving any distinct mark. Sanofi-Aventis (SNY), maker of the Imovax brand of vaccine, notes on its Rabies.com Web site that there's an "eerie ring of truth" to the horror tale Dracula. "Like Dracula," the site says, "bats have crept up on sleeping people, bitten them, and flown off."
The advice of four doctors and a rabies researcher I contacted was not something my wife and I were going to argue with. Rabies is always fatal, and, according to the U.S. Centers for Disease Control, bat bites have been the source of 92% of the 37 human cases in this country since 1990, based on testing that can trace variants of the virus to a particular species. The vaccine is expensive -- about $1,500 for the full treatment -- but that is generally covered by insurance. Some 40,000 Americans receive PEP every year for bites or suspected bites from bats, dogs, raccoons, and other critters. (Because rabies has an incubation period ranging from a few weeks to many months, the vaccine is effective if given immediately after exposure.)
Something about this race to vaccinate strikes me as a bit nuts. Face it, bats are everywhere. An estimated 1.5 million live under a single bridge in downtown Austin, Tex. You may see them at dusk whirling over the lake in New York City's Central Park. Yes, they get into houses, and about 5% of the bats found indoors have tested positive for rabies. Still, just one or two people a year die in the U.S. from an undocumented bat bite, the Sanofi Dracula scenario. In New York, 82% of the 1,799 encounters with bats that led to vaccinations in 2005 were based merely on suspicion of exposure, rather than a known bite. Is it possible my wife and I let the horror stories hamper our ability to take a hard-nosed look at the numbers? Have our health providers become infected with hysteria?
As I drove Sophia to get her second injection, I thought about traffic deaths: 0.8 per 100 million passenger miles. I suggested that Sophia take ibuprofen to alleviate the anticipated soreness, then recalled data I'd seen on an often-fatal skin disorder the drug triggers in some people. It's extremely rare, but is it any more so than getting rabies from a bat with no sign of a bite?
Meanwhile, the risk decisions seemed to branch out endlessly and inconclusively. Sophia was about to get on a plane (0.02 deaths per 100 million passenger miles) for Israel(!), where she would need to get her last three shots. The package insert for the vaccine said it needed to be kept between 35 and 46 degrees, but not frozen. Would it suffice for her to transport it with cold packs in an insulated bag? And if it got confiscated by security or customs, would it be O.K. for her to continue with the only brand of vaccine available in Israel, which is made by a different company using a different method? Scientists I spoke with sounded varying degrees of caution on both of these questions. (My wife and I ended up answering yes to both.)
The issue that vexed me most was the premise that set us down this whole path: that post-exposure rabies prophylaxis is advisable just because a person may have slept in a room with a bat. It turns out that since 1999, CDC guidelines have stated that PEP "can be considered" when "a sleeping person awakens to find a bat in the room or an adult witnesses a bat in the room with a previously unattended child" and "rabies cannot be ruled out by testing the bat."
When New York State began publicizing this seven years ago, says Dr. Brendan C. Brady, a physician in Canandaigua, N.Y., his county saw a "huge spike in the money we were doling out for something that basically never happened." The guidelines, he says, are "pretty reasonable," but the interpretation has become "like the Chicken Little story." Now "you'll never get a doctor to tell you not to get vaccinated," Brady says, because they have nothing to gain by advising against it. A 1998 study by Oregon health officials estimated that, because unrecognized bat bites are so rare, it would cost the state $180 million to prevent a single case of rabies from such an incident if the guidelines were fully followed.
I got on the phone with Charles E. Rupprecht, chief of the CDC's rabies section, who acknowledged that the guidelines often fall prey to defensive medicine. Doctors should ask detailed questions to see if PEP is necessary, he says, such as inquiring about where the bat really was and how heavily a person sleeps. (Out of curiosity, he tested his own kids when they were young by pinching them with forceps; they did not awaken.) But "everyone's risk-averse," Rupprecht says, so they "equate what CDC is saying with every time you have a bat in your house you have to get prophylaxis." In some cases, it goes beyond even that. Camps in New York have sent busloads of kids to get vaccinated, simply because bats have flown through their cabins or dining halls -- while the campers were awake.
Bat experts scoff at this. Merlin D. Tuttle, founder and head of Bat Conservation International in Austin, thinks people know if a bat has bitten them. He suspects that many bat rabies cases for which the CDC has found no bat exposure might be shown to involve a bite if more investigation were done. That's because the CDC classifies bat rabies cases as being of "unknown" origin unless it can get a credible account of exposure to a bat from the victim or his family. The victims are often dead or deranged by rabies by the time an inquiry is begun.
So where did my reporting lead me on our decision to get Sophia vaccinated? There certainly seems to be controversy about whether to act on a bite that may never have taken place. And the ultraconservative impulse of doctors to proceed with PEP at even the hint of proximity between person and bat seems hard to justify as a matter of health economics.
But in a matter of life and death, I look for consensus, not controversy. I make decisions as a parent, not as a health economist. Faced with the same circumstances in the future -- an infinitesimal chance of mortal harm vs. a guaranteed way to avoid it -- I'm pretty sure I would do the same thing all over again. One thing I do know: If we find a bat in our house, I'm sending Sophia to catch it.
By Michael Orey