The old saying is "when you hear hoof-steps, think horses, not zebras." In a medical context, it means common things occur commonly, so don’t start off thinking about wild and bizarre conditions before you’ve ruled out the usual suspects. Along that line, when I hear "rabies," I think "bats, raccoons, dogs, cats, foxes…" I don’t think about… zebras.
Considering there aren’t that many zebras in Ontario, and even in places where there are zebras, most people don’t have a lot of contact with them, it makes sense that zebras don’t typically make the rabies suspect list. But that doesn’t mean zebras can’t get rabies.
A Letter in Emerging Infectious Diseases (Lankau et al, 2012) describes one such unusual scenario. In January of 2011, an orphaned zebra foal was taken in by a safari lodge (that’s probably not too unusual of an occurrence), and not surprisingly, tourists were allowed to handle and feed the foal. Unfortunately, the foal was bitten by a dog at the end of July. The dog was suspected of being rabid but it doesn’t seem like any changes were made to how the baby zebra was handed. Unfortunately, the foal died at the end of August and rabies was confirmed. Lodge staff tried to contact people who had visited during the July-August time period, mainly through emails to travel-booking agents who (it was hoped) forwarded the information to travelers.
Several US travelers contacted CDC after getting the email and their risk of rabies exposure was investigated.
- CDC obtained names of 243 travelers who were at the lodge, 136 of whom were from the US.
- They worked with the assumption that the outside window for rabies virus shedding by the zebra was a 14 day period leading up to its death. Seventy-seven (57%) of the US visitors had been there during that period.
- Twenty-eight of those visitors had already started post-exposure treatment for rabies. None of those individuals had high-risk exposures, 2 had moderate-risk exposure while the rest had low or no-risk exposures, so treatment would not have been recommended for most of them. That’s probably because the information went from the lodge to travel agents to travelers, and then to the peoples’ general physicians (who are generally less well versed in rabies exposure issues) rather than through public health.
- The cost of rabies post-exposure treatment is at least $4000/person in the US (although I know of cases where the cost was much higher), so at least $100 000 was wasted, in addition to stress and other factors.
Some take home messages
- People need to think about animal contacts when on vacation. Travelers that go to rabies-endemic areas need to pay particular attention to avoid high-risk contact with animals.
- Facilities that allow animal contact need to protect the public. Rabies vaccination of this foal might have prevented its infection and the subsequent human exposures.
- If an animal has been attacked by a rabid animal, don’t let people come into contact with it!
- Rabies exposure is a medical urgency, not an emergency. There’s time to make sure things get done right, and public health personnel should be involved in discussions of exposure and treatment.