Rabies Alert

Q&A

Dr. Charles Rupprecht, Chief, Rabies Program, Centers for Disease Control and Prevention

Outpost: Why is the incubation period for rabies so variable?

Charles Rupprecht: With many things in rabies we say ‘it depends’—on the dynamic between agent, host and environment, on how much virus is being inoculated [introduced into the body], on where it’s being inoculated, on if the exposure is a bite or a lick. The variables are dose, route, severity, proximity [of the bite] to the central nervous system [and brain] and host susceptibility, which varies.

OP: What animals should travellers be most wary of?

CR: Most human cases are due to dogs—dogs are the global reservoir for rabies….But the two major reservoirs we’re concerned about are carnivores, particularly of the canine family—dogs, foxes, coyotes, jackals, but also raccoons and skunks—and bats, which form a reservoir for rabies all over the world. We’re more concerned about the unprovoked bite by an obviously ill animal in a hyperendemic country, than we are by a bite where rabies hasn’t been reported.

OP: Is it also true rabies can surface in livestock, such as cows?

CR: Yes, we believe all mammals are susceptible…cows, horses, sheep, goats, just about any mammal that has a risk of exposure to the reservoirs—meaning carnivores and bats. [But cows] don’t have the same kind of teeth and hence are unlikely to cause the same degree of damage—to drive the virus deep into tissue. So I’m less concerned about cows than dogs with rabies.

OP: The quality of biologicals in many countries is not always guaranteed. Is this a concern for post-exposure rabies treatment?

CR: We have three major concerns here: one, the availability of biologicals at all; two, the availability of quality biolgicals; and three, counterfeit biologicals. And we have had human deaths from counterfeit rabies biologicals. We had a situation with somebody on a [school] semester at sea, where they found a bat on the deck of the boat and made a pet of it. Then [he/she was] bitten! The bat died, was sent to us, where we found out it was positive [for rabies]. The poor student had to fly home from Latin America to North America just to receive rabies prophylaxis, at undue cost, ruining [his/her] semester. Don’t provoke exposures, and find out whether you should have pre-exposure. Have a plan of action in case you’re bitten in a country where rabies is a concern.

OP: Pre-exposure and post-exposure medication is the same, correct?

CR: Pre-exposure vaccination and post-exposure vaccination is the same. [But] the post-exposure vaccine also contains rabies immunoglobulin [antibodies], because when you’re exposed to the virus it takes a while for you to respond to the vaccine. And we want you to have a preformed response, preformed antibodies, that attack the virus immediately.

OP: If a short-term traveller is bitten, but has taken pre-exposure vaccine, should they seek treatment while abroad, or is it safe to wait until they get home?

CR: I’m never happy saying one is safe, because you’re gambling. Once you’ve given the advantage to the virus, your chances for intervention go down. Rabies [is always] a medical emergency.

When to Ask About Vaccination

• If you’ll be in a country identified by a public health agency as hyperendemic for rabies; a place where dog rabies is known to occur.
• If you’ll be in a remote area where: wild rabies likely exists; animals roam free; post-exposure treatment may be an issue; repeated exposure to animals and wildlife is possible.
• If you’ll be on a longer trip, where multiple opportunities for exposure exist.
• If you’ll be doing an activity like hiking, cycling, camping or spelunking where you may be exposed to rabid animals, particularly bats.
• If you’re travelling with children, who like to pet animals and may not tell you if they’ve been scratched or bitten, and who account for the largest portion of human rabies deaths worldwide.

Rabies Risks While Travelling

• Provoking an animal to bite by petting or encouraging physical contact.
• Getting bitten, scratched or licked by an infected animal, since it’s excreted through saliva; scratches transmit rabies because
 animals lick paws.
• An unprovoked animal attack, especially by a dog, which can indicate rabies.
• Contact of infected animal saliva on mucous membranes of the eyes, mouth, nose (though rare).

Rabies Vaccine and Treatment

• CDC says thorough, vigorous washing of any animal bite or scratch (and licked skin) with copious amounts of soap and water
 for several minutes (and iodine, if possible) substantially reduces
 risk of getting rabies, as this physically dislodges the virus;
 remove any clothes you were wearing when bitten.
• Pre-travel vaccine: three weekly doses; confers some protection
   if you’re unknowingly exposed.
• Post-exposure treatment: five weekly doses, as soon as possible.

Note: This information is a guideline only. Always get individual medical advice from a travel health doctor. For more info on rabies and country prevalence go to: Public Health Agency of Canada, www.phac-aspc.gc.ca; CDC’s Yellow Book on International Travel 2008 (Chapter 4); WHO www.who.int/rabies. Dr. Terill Udenberg is a breeder, member of The Canadian Kennel Club and canine competition judge.

This entry was posted on Wednesday, July 30th, 2008 at 3:23 pm and is filed under Health. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a comment, or trackback from your own site. Add to del.icio.us.