Dear Doctor Dysphoric:

Dear Dr. Dysphoric:

I have a slightly unusual question. Today a llama bit me. It was lying on the ground and I decided to try to ride it. The bite almost proved fatal as the shock of being bitten and the speed with which the llama jumped up nearly caused me to fall off of the side of the mountain. My skin was not broken, but the area is red and swollen. Can you catch rabies from a llama? If so, what should I do about it?

--Not Ready For Rabies


Dear Not Ready For Rabies:

I have to admit that llama bites and rabies are not exactly routine here Washington Heights. In fact, rabies is actually rare now in the United States. But once acquired, rabies is one of the most fatal infectious diseases. According to a 2003 article from the Journal of Clinical Infectious Diseases, there is only one case report of a person who has developed rabies who has actually survived!

Rabies is caused by an RNA virus from the Rhabdoviridae family. The virus is transmitted by the saliva of an infected animal entering a wound. [There have been a few cases of transmission from non-bites, but these were in caves with zillions of infected bats flying around spitting down travelers throats, and other weird stories.] From the bite wound, the virus climbs into peripheral nerve cells. The nerve cells have tails ("axons") which stretch way up to the brain. The virus deposits itself in the brain, the brainstem, and the spinal cord. It eventually spreads via other nerves to the heart, salivary glands, and other organs. [The pic on the above right is the "negri bodies," or collection of virus particles, on a piece of brain tissue stained with H&E. Courtesy of CDC.]

Besides it's impressive fatality rate, rabies causes a horrific clinical syndrome. It has been immortalized in literature for hundreds of years, including the character Tea Cake in Zora Neale Hurston's classic There Eyes Were Watching God. Patients complain of hypersalivation and throat spasms, then become progressively hyperactive and generally nutso. This is topped off by the pathopneumonic hydrophobia (fear of water). Eventually the patient falls into a coma and dies. [The pic on the right is of a rabies patient who required physical restraints. Courtesy of CDC.]

There are two kinds of rabies prophylaxis: pre-exposure prophylaxis (vaccine) and post-exposure prophylaxis. Many travelers are counseled by their doctors to get the vaccine before going to countries where rabies is endemic. If you have not had the rabies vaccine, post-exposure prophylaxis (PEP) is your only option. PEP includes both "active" and "passive" immunization. Active immunization is five gigantic shots of the rabies vaccine into to the deltoid muscle, on days, 0,3,7,14, and 28 after exposure. Passive immunization is a shot of Rabies Immune Globulin (RIG) around the bite wound.

I think we likely agree that PEP is not a walk in the park. In your case, there are several variables to consider when making your decision. First, did you actually have an exposure? If the bite did not break the skin, I think the likelihood is low. Second, what is the likelihood that the llama actually has rabies? Rabies is certainly endemic in Peru, but is usually in bats and dogs, not llamas. Even if llamas can harbor rabies, the likelihood that your llama has rabies is also quite low.

In summary, rabies is both an unpleasant and fatal disease. It can be prevented by post-exposure vaccination, even if you have not had the rabies vaccine prior to the bite. The PEP is an ordeal, however, and you do not want it if the likelihood of rabies exposure is close to nil. My advice is to go to a local doctor and ask about the prevalence of rabies in that part of Peru, and whether they have seen rabid llamas. If the prevalence of rabies in llamas is low, your likelihood of acquiring rabies without a true bite is close to zero. If they have seen a sudden outbreak of rabid llamas at Machu Picchu, you can consider PEP under the supervision of a doctor.

Hope this helps--

Doctor D