Rabies baiting is a highly effective way to reduce rabies in wildlife populations. As we’ve discussed before, in Ontario this involves air-dropping edible rabies vaccine. These baits are dropped in key rural areas, but there is the potential for curious people to come into contact with the vaccine if they handle baits that they come across. It is recommended that people avoid contact with the baits and wash their hands if they do come into contact with one, because the baits contain a live virus. They do NOT contain live rabies virus. Rather, they contain a vaccinia virus that has been manufactured to produce immunity to rabies virus. The risk of human infection is low, but as we constantly get reminded with infectious diseases, low doesn’t mean zero.
Today’s MMWR reported a case of human vaccinia infection associated with a rabies bait. In August, a 35-year-old Pennsylvania woman was picking berries and her dog and found a rabies bait. The dog punctured the bait packaging and the woman subsequently handled the bait. It took around 30 minutes for the woman to reach somewhere she could wash her hands, which she then did. This person had a few factors that put her at higher risk of developing an infection, including some skin lesions on her hands from berry thorns, and she was on multiple immunosuppressive drugs.
The day after exposure, her doctor took blood samples for rabies and vaccinia virus antibodies and examined her hands. Skin lesions (papules, i.e. little bumps) developed three days later. These lesions were tested and vaccinia virus was found in them. The skin lesions progressed and she was hospitalized a couple of days later. She was treated with antibodies against vaccinia virus because of the progression of disease and her compromised immune system. She went on to develop muscle aches, headache and a swollen lymph node. She was treated with more antibodies and an experimental antiviral drug. She ultimately responded to treatment and was discharged from the hospital on day 19.
This is the second reported human infection associated with a rabies bait. Considering the millions of baits that have been dropped and the presumably relatively large number of people that have had some contact with the baits, the overall risk of disease is still very low. This person was at high risk because of her immunocompromised status, and it’s likely that an otherwise healthy person would not have developed an infection like she did. The big problem here was her contact with the bait. She did everything right after that: washed her hands as soon as she could, called the Department of Health, went to her physician and ensured that testing was done, but she still got sick.
Avoid rabies baits. The risks are low but why take any risk? People that have compromised immune systems or skin diseases should take particular care. If you’ve been exposed to a rabies bait, wash your hands ASAP and contact the local health authorities to determine if anything else should be done.