Rabies - the name conjures images of stray dogs slinking along, growling, foam dripping from their jaws. It is the thing mothers warn their children about when they want to pet strange animals. It used to trigger the alarm cry "Mad dog", and people would barricade themselves in their homes until the menace was past.
Rabies is an infectious disease of mammals. It is caused by a virus in the order Mononegavirales, family Rhabdoviridae, genus Lyssavirus. It is usually transmitted through the bite of an infected animal, or through contact with its saliva, although other modes of transmission have been reported. These include corneal transplants, mucous membrane contamination, and aerosol transmission.
Rabies is endemic in most areas of the world; in the U.S. the only state in which rabies is not endemic is Hawaii. U.S. cases cluster along the East Coast and in eastern Texas. The main vectors, in 93% of U.S. cases, are wild animals, especially raccoons, skunks, foxes, coyotes, and bats. Only 7% of U.S. cases are due to domestic animals. In 2001, 7,437 cases of rabies or rabies exposure were reported to the CDC. Rabies infection in humans is rare in the U.S., with only one to three cases reported each year. The CDC confirmed three human cases in 2006. On average, 1 to 2 rabies deaths per year occur in the U.S.
The incubation period for rabies varies, and may be as short as a few days, or as long as several years, but generally lasts 3 to 12 weeks. During this time, the victim (human or animal) is infected, but shows no signs of the disease; in the beginning of the incubation period the virus cannot be detected by laboratory testing. The length of the incubation period depends on several factors: the particular strain of virus, how many virii were transmitted, the method of exposure, and the location of the exposure. As a general rule, the closer to the brain the exposure occurred, the shorter the incubation period. During the incubation period, the virus slowly replicates, traveling along nerve fibers towards the brain. The arrival of the virus in the central nervous system is heralded by the onset of symptoms.
Initial symptoms of rabies are generally nonspecific, and include:
These symptoms progress within days to symptoms of cerebral dysfunction
, such as:
There are two forms the disease can take: the furious form and the stuporous form. Animals or people suffering from the furious form will be very agitated, and will attack without provocation. Human patients may scream and curse at the top of their lungs. Sufferers from the stuporous form will simply become very lethargic and slip into a, well, stupor. These are the instances of wild animals that appear tame and fearless and will allow themselves to be petted by humans. In both cases, the symptom that gives rabies its other name, hydrophobia, is the throat spasms that occur when a victim tries to drink. They are very painful and intense, and eventually the thought of drinking alone can bring them on. Animals with this symptom avoid water, and in people the spasms can be caused merely by hearing water being poured.
Once the acute symptoms start, the disease is almost invariably fatal. There have been seven documented rabies survivors to date. EVER.
Six of these survivors had had either pre- or post-exposure prophylaxis. Pre-exposure prophylaxis consists of a series of rabies vaccinations, given to people in high-risk occupations, such as veterinarians, animal control workers, and others whose jobs bring them in frequent contact with wild animals, and also to people whose hobbies put them at risk, such as spelunkers.
Post-exposure prophylaxis involves rabies immune globulin and a series of rabies vaccinations, and is given to those patients with a known rabies exposure, or to those with a high index of suspicion for rabies exposure. Once a victim begins to show the symptoms of rabies, prophylaxis is ineffective.
There is ONLY ONE person who has ever survived rabies without either pre- or post-prophylaxis. Her name is Jeanna Giese, and she is 15. Jeanna was exposed to rabies when she was bitten by a bat during a church service on September 12, 2004. The church members assumed that only healthy bats could fly, so after the bat flew into a window, they picked it up and threw it out the door.
On October 18, 2004 Jeanna was admitted to the hospital with the symptoms of cerebral dysfunction such as change in level of consciousness and slurred speech. She had not had any form of rabies prophylaxis.
Doctors at the Children's Hospital of Wisconsin, faced with their patient's inevitable death, initiated an innovative treatment. They put the girl into a drug-induced coma, and gave her a cocktail of four antiviral medications.
On November 24th, 2004, the CDC announced that Jeanna is the first human ever to survive rabies without a vaccination. Her doctor states that he expects her to make a full recovery. At this time she is responding appropriately to questions by pointing to a message board or nodding her head.
UPDATE: As of February 3rd, 2005, Jeanna is back at school. She used a wheelchair at first, but is now walking and talking. She still has some neurological deficits but is expected to make a full recovery.
Rabies does not kill through causing brain damage, but through paralyzing the brain centers which control vital functions such as breathing and swallowing. The doctors are unsure whether the medications given caused the girl's recovery, or whether the supportive treatment simply allowed the girl's body to heal itself. The girl's father credits the power of prayer with her miraculous recovery. Until the same treatment is used on another patient in the same situation with success, its success is merely another anecdote.