Rabies in Maine

So far in 2010, there have been 30 documented cases of animal rabies in Maine. This is up from recent past years (see graph from Maine Center for Disease Control [CDC]). And Kennebec and Cumberland counties have had the most (MeCDC map), probably because they have the highest human population, so more rabid animals are identified. What is rabies and when should you worry about it? Here is a quick summary.

Rabies is caused by the rabies virus which infects nerve tissues. When a mammal, including a human, is exposed, usually by the bite of an infected animal, the virus gradually travels up the peripheral nerves from the exposure site, eventually to the brain. This takes from 2 weeks to 2 months, depending on how far from the brain the bite/exposure was.  In the brain it causes an encephalitis, brain inflammation which results in confusion, fever, and eventual death. But this is very rare; fewer than 5 people die from rabies in the US each year. But over 20,000 are vaccinated yearly because they may have been exposed to a rabid animal.
Bats, raccoons, skunks and foxes are the most common transmitters of the disease (see CDC table 1 for 2010). The latter 3 act strangely when infected, so the usual story is that a raccoon, fox or skunk bites a person after seeming unusually unafraid of people. Only bats are not killed by the disease and so are thought to be the principle reservoir. Worldwide, dogs transmit it frequently. But, since the extensive immunization of pets, especially dogs, they rarely catch or transmit the disease in North America now. Cat bites are now the most common domestic animal exposure requiring post bite preventive treatment, mainly because they are less often vaccinated and because they are less easy to catch and confine if they bite a person. If a domestic animal does not get sick after a 2 week confinement, then they did not have rabies and the person they bit does not need vaccination. Wild animals rarely can be so confined but they can be killed and their brain quickly studied by the Maine CDC. Bats are a special case. They don’t have to bite to transmit the disease, but there has to be substantial close exposure. Their presence in a room with you is not enough. But if one sleeps with you or you go spelunking in bat caves, you should be immunized. Other wild or domestic animals are very rare transmitters.

Other animals (woodchucks, squirrels, cows, etc) can very rarely transmit the disease if they are infected

Vaccination is done now with human diploid cell vaccine in a 5 shot series done on days 1, 3, 7, 14 and 28. In the old days, we used a duck egg based vaccine which required more doses and was more painful. The vaccine is expensive ($700 for the series) and not available free but given no matter ability to pay by most hospitals in Maine, if necessary. An additional shot of human immunoglobulin is usually also given into the leg muscle and into the wound of high risk bites or extensive bat exposures.

So, vaccinate your pets before hand; avoid strangely tame wild animals and bats . But if you or your family is bitten or intimately exposed to bat(s):
•confine the domestic animal that bit you (dog or cat); or kill the wild animal, and refrigerate it (at least it’s head) until it can be gotten to the state lab in Augusta for study. Or ask the Vienna animal control officer, Donald Tibbetts to help you.
•get treatment for the wound and accept post exposure treatment within a few days if it is appropriate.
• Or call me for advice or help.

Dan Onion, Vienna Health Officer, 293-2076

Table 1. Current quarter and year-to-date animal rabies by county, town and species in Maine 2010