by Dr. Robert C. Reiser
The recent attacks on U.Va.’s Grounds by a fashion-loving fox (she also stole a sweater) and the subsequent hysteria got me thinking about rabies. The bizarre decision to kill a randomly trapped and healthy gray fox suggests to me that some education on the nature of rabies is in order.
Rabies is an ancient disease. Records of it in Mesopotamia date back over four thousand years ago, but it is still a modern scourge; 55,000 people die of rabies every year, mostly in the developing world.
I visited one the hot spots of this epidemic recently; Vietnam has the second largest number of cases in the world (India is number one). The overwhelming majority of these cases are from domestic and feral dog bites.
However, in Vietnam another mode of transmission from dogs has been well-recorded. Cooks can get rabies while preparing dog for dinner. Dog is considered a delicacy and some restaurants serve it exclusively. We avoided those restaurants but not for fear of rabies. Fully cooked dog is safe at least as far as rabies is concerned.
The most terrifying thing about rabies is its extraordinary lethality. It is essentially 100 percent fatal once symptoms appear and nothing is going to save you. So I understand the hysteria, but to keep it in perspective, it is also 100 prevent preventable with proper post-exposure vaccination and we do an extraordinary job at this. In the USA, the number of deaths from rabies averages three per year, and two of those are acquired outside the USA during travel to the developing world. In order to achieve this, we massively overtreat potential exposures; each year in the U.S. we give 39,000 patients post-exposure vaccines at a cost approaching $600 million dollars.
Rabies is transmitted through the saliva of an infected and sick mammal across broken skin. Intact skin will not allow transmission.
If the animal can be watched for ten days and it does not sicken, it did not have rabies in its saliva at the time of the bite. No treatment is needed and no foxes need to be killed. Any mammal can potentially transmit rabies although some, such as rabbits, mice and squirrels, have never been documented to transmit rabies to humans.
Some controversy exists when it comes to bedroom bat exposures, i.e., waking up to find a bat in your bedroom. From 1980 to 1999, there were 21 cases of bat rabies in the U.S., of which only two had a documented bite, 12 had physical contact with a bat without a recognized bite, and 7 had no documented bat exposure at all. Thus the recommendation developed that all bedroom exposures should receive the 6-shot series of rabies vaccine. There were some problems with the data collection in these 21 cases however.
A more careful analysis this year by a group of Canadian researchers revealed that bedroom exposures to bats are surprisingly common; 1 in 1,000 people reported one. Less than 5 percent of those people sought treatment. Applying those numbers to the population at large and the incidence of bat rabies means that we would have to treat (with 6 shots) 2.7 million people to prevent one case of bat rabies. This is upwards of 2 billion dollars to prevent one case. This is probably the least cost-effective public health preventative measure ever devised.
Ah, but what if it is you? The virus travels from the bite site up your nerves to your brain. This can take anywhere from several days to several years. The average is 1 to 3 months. You are not sick at all. The virus replicates in your brain and travels back down your nerves throughout your body. For about a week you have a low-grade fever and feel like you have the flu. When the virus reaches your salivary glands it reproduces massively. Now you begin acting strangely, gagging and foaming at the mouth at the sight of water (thus rabies’ other name, hydrophobia), rushing around furiously snapping and biting, lapsing in and out of consciousness alternating with severe agitation for a few days before succumbing to coma and death within a week or two. Alternatively, a small percentage of cases skip the “furious rabies” classic presentation and become progressively paralyzed, comatose and dead. This is called “dumb rabies.”
I’ll take the shots!
On a final note, only one person is known to have survived rabies without the post-exposure vaccination. In 2005, a 15-year-old Catholic schoolgirl picked up an injured bat in the church at her school in Fond du Lac, Wisconsin and was bitten. She and her mother washed out the bite after school but did nothing else. One month later, after typical rabies symptoms developed, she lapsed into a coma and only then was diagnosed with rabies. Her doctor at Children’s Hospital of Wisconsin had never treated rabies but put together an experimental protocol based on some reading. After a month in a medically induced coma with near total cessation of brain activity they woke her up and she survived with some severe neurologic deficits. She is now 19, fully recovered, and hoping to be a veterinary tech someday. After all she still loves animals and is now naturally immune to rabies to boot.
Since that time the ‘Milwaukee Protocol” that was used has been tried on multiple patients with no further success. Everyone else has died. So if you suspect rabies exposure, call your doctor or the health department for advice about vaccination.