rescue. reunite. rehome. rethink.
  • Share to Facebook
  • Twitter
  • Email
  • Print

Rabies: Staying Vaccinated and Informed

Pre-exposure vaccinations are important, but they are only the first step in protecting yourself against the virus

Pre-exposure vaccinations are important, but they are only the first step in protecting yourself against the virus

If you've already had your preexposure rabies vaccinations and think you’re forever immunized, think again. You’ve taken the first important step toward protecting yourself from the deadly virus, but probably not the last.

Many animal care professionals go to the doctor for their pre-exposure series of shots and assume they’re protected indefinitely. “Because they’ve had pre-exposure, most of the time people think, ‘Well, that’s it, I don’t have to worry about it,’ ” says Karon Damewood, chief of zoonotic diseases for the Center for Veterinary Public Health in Maryland.

It’s an understandable conclusion. After all, most of the vaccines we receive and administer to animals provide long-term protection, so it would seem to follow that human rabies vaccines act in a similar way.

But they don’t. Rabies pre-exposure vaccinations are just one part of an overall regimen designed to protect people in at-risk professions—diagnostic laboratory work, shelter and rescue work, and veterinary care—from contracting the disease.

Quick Facts

? The pre-exposure rabies vaccination series consists of three shots administered over the course of three weeks to a month. Pre-exposure vaccines do not preclude post-exposure therapy following a bite; they simply make that therapy shorter. Other benefits include the possibility of increased protection for those unable to get to post-exposure therapy immediately, as well as for those who are unaware they have been exposed at all.

? The post-exposure rabies vaccination series consists of two shots within four days for those who have already been pre-exposed. For those who’ve never received preventive therapy, the post-exposure series includes an injection of human rabies immune globulin at the site of the bite to neutralize the virus, plus five shots over a month-long period.

? The recommended course of action immediately following a bite or scratch is to vigorously wash and scrub the wound area. Then call your doctor and the local health department. Depending on the circumstances—for instance, whether the bite was “provoked,” whether the biter has had a rabies vaccination, and whether the animal can be quarantined for observation—you could end up either skipping post-exposure shots or having to undergo the full series.

Consisting of three shots administered within three to four weeks of each other, the pre-exposure series induces production of antibodies to the rabies virus. How long that production lasts, however, will depend on the person—which is why people who have received pre-exposure shots need to have their blood tested every two years to ensure sufficient levels of antibodies are still present, according to the Centers for Disease Control and Prevention (“Human Rabies Prevention—United States, 1999: Recommendations of the Advisory Committee on Immunization Practices,” Morbidity and Mortality Weekly Report, January 8, 1999). Booster shots are given any time tests show that antibodies have waned.

But, contrary to popular belief, pre-exposure vaccines and boosters do not provide full protection; they just reduce the number of shots you have to get once you’ve been exposed to a potential rabies carrier. Bite victims who’ve been vaccinated with the pre-exposure series need only two shots over the course of four days, but the regimen is much more intense for people who haven’t been preexposed: an initial injection of human rabies immune globulin at the site of the bite to try to neutralize the virus, plus a full series of five vaccinations over the course of a month.

Aside from the reduction in post-exposure shots, pre-exposure therapy has practical protective benefits, according to the CDC. It may enhance immunity in people who experience delays in obtaining post-exposure treatment, and it may help safeguard those who aren’t even aware they’ve been exposed to rabies.

Though cases of human rabies in the United States are rare, each year an estimated 18,000 people receive the pre-exposure series and 40,000 receive post-exposure vaccinations. And for good reason—there are only three documented cases of human survival post-infection, says Damewood, and the victims in those cases suffered permanent and severe neurological damage.

Rabies virus is carried in the saliva of mammals. The incubation period for the virus in humans can vary from several weeks to several months, according to the CDC, which includes charts in its report that provide a basis for analyzing if and when postexposure shots are necessary following an incident. Exposure can occur through either a bite or a scratch, but many variables affect whether the situation is merely cause for quarantine and observation of the animal or immediate grounds for beginning post-exposure treatment of the human. Each incident of potential exposure must be analyzed individually to decide on the most appropriate course of action, says Damewood.

Where scratches are concerned, “first off it’s significant to know whether it’s a scratch with a tooth as opposed to a claw,” she says. “Number one, a tooth scratch is obviously of more concern because of the potential for saliva. However, if a cat that is rabid was just licking its paw and it scratches the goody out of you, then that would be of concern. So you see how many shades of gray there are? And that’s why we must do a risk assessment with each and every case.”

Sometimes rabies cases don’t make themselves readily apparent. Recently in Maryland, the staff of a veterinary clinic treated a “nasty eye” of a cat who came to them, watched the cat’s condition steadily improve, began preparing him for adoption, and tried to find him a home—all the while encouraging interaction between the cat and dozens of different people. Suddenly, in the midst of it all, the cat died. “The veterinarian had enough sense to test it, and it was hotter than a firecracker,” Damewood says. “And so we had about 96 to 100 or so people that had to get post-exposure [shots] as a result of . . . indirect exposure.”

Anyone who has been scratched or bitten should immediately wash the area with soap and water, according to CDC guidelines. “Scrub it. Wash it out. Even to the point of where it’s bleeding and hurting even more, wash it well,” says Damewood. “That’s your first line of defense because you want to dilute and get rid of as much virus as you can.”

Next, potential exposures should be reported immediately to a private doctor and to the local health department like the one Damewood works for. Because of the rarity of human rabies cases, physicians don’t have a lot of experience with them and often depend on municipal and state health departments for the latest information. “That’s why we are here, just to point them to [CDC guidelines] and to help them sort through the pieces of information that will help them make an informed and reasonable decision to protect the health and safety of their patients,” says Damewood.

For more information on both human and animal rabies vaccination protocols, visit the website of the Centers for Disease Control and Prevention at www.cdc.gov. The 1999 Human Rabies Prevention report is available at www.cdc.gov/mmwr/preview/mmwrhtml/00056176.htm.

 

Powered by Convio
nonprofit software