By Chris Woolston, M.S.
What is rabies?
Rabies is one of the oldest diseases known to mankind, and it used to be cause for panic and hysteria. A Spanish neurologist even speculated that rabies may have spurred legends of vampires. Until recently, being bitten by a rabid animal was a death sentence. Even now, we can only prevent the disease, not treat it. Once symptoms appear, rabies is almost always fatal.
Thanks to effective vaccinations and treatments, only a handful of people die of rabies in the United States each year. But the danger isn't just a myth: About 40,000 Americans get rabies shots each year after possible exposure to rabies. Rabies is present everywhere in the country except for Hawaii, which is the only rabies-free state. Around the world, an estimated 55,000 people die of rabies each year, mostly in rural areas of Africa and Asia.
Now we know that rabies is caused by a virus, commonly known as the rabies virus, which can infect all warm-blooded animals. The main carriers are carnivores (meat eaters) and rodents. Once in the body, the rabies virus travels up the nerves to the central nervous system and causes an inflammation in the brain. This explains why the hallmark symptoms of rabies are mental, such as hallucinations and agitation.
How do people catch rabies?
Most cases of rabies in humans start with an animal bite. If the animal has the rabies virus in its saliva, the wound can become infected. Once in the body, the virus spreads quickly to the spinal cord and brain. It is possible to catch the disease without getting bitten. A person could, for example, be licked by an infected animal and pick up the virus if saliva gets into an open sore, but this almost never happens.
Most people associate rabies with dogs, but more than 90 percent of rabies-infected animals in the U.S. live in the wild. Raccoons are the most commonly reported animals with rabies, and bats are a close second, followed by skunks and foxes. Even rabbits and small rodents can be rabid, but the virus is more common in larger rodents like raccoons. Domestic animals -- including dogs, cats, and cows -- can carry the virus, too.
From 1995 to 2006, there were only 37 human deaths from rabies in the U.S. In 75 percent of cases, the patient was bitten by a bat. In certain parts of Africa, Asia, and Latin America, dogs are still the most common sources of rabies in humans.
How can I tell if an animal is rabid?
Animals can carry the rabies virus for three to 12 weeks before ever showing any symptoms, so you can't always tell if an animal has rabies just by looking at it.
Once symptoms do kick in, an animal may foam at the mouth -- a classic sign of rabies that has been recognized for centuries. Rabid animals may also be unusually aggressive and lose their normal fear of humans. Alternatively, an animal with rabies may become extremely sluggish and reclusive. Paralysis in muscles may cause the animal to hang its head or drag its hind limbs.
But remember: Even if an animal appears completely healthy, it could still carry the rabies virus. Unless you know an animal is up-to-date on vaccinations, you have to treat every bite as a possible rabies risk.
What are the symptoms of rabies in humans?
Humans infected with rabies usually don't show any symptoms for one to three months, but this window can range from days to years. During this time, the virus can hide inside nerves, where the immune system can't find and destroy it. Once symptoms appear, it's too late -- rabies is almost always fatal no matter what kind of treatment a person gets.
In its early stages, rabies feels like lots of other illnesses. At first, there may be a tingling, twitching, itchy, or painful feeling around the site of the bite. A person may have a fever, headache, and a vague sick feeling, nothing that would cause much alarm. This period may last for about two to 10 days.
Once the virus reaches the brain, the acute phase begins. Possible symptoms include insomnia, hallucinations, trouble swallowing, fear of water (due to difficulty swallowing), confusion, convulsions, muscle spasms, anxiety, and excitation. About 20 percent of rabies cases develop into the paralytic form, without the typical symptoms of the more common "furious" form. In either form, the patient eventually slips into a coma and dies.
How should you treat an animal bite?
If you've been bitten or scratched by an animal that might carry rabies, immediately wash the wound thoroughly with soap and water and disinfect with either alcohol or iodine. Then call your doctor promptly. If the animal is a healthy domestic pet, it may be put under confinement for several days and observed for symptoms of the disease. Wild animals will be captured, if possible, and euthanized to test for definitive evidence of rabies in their brains.
If there's been any physical contact with a bat -- with or without evidence of a bite -- your doctor may want to start rabies treatment. Bats have tiny teeth which may not leave easily visible marks. In most recent cases of bat-associated viral infection in the U.S., there was no visible bite mark present, and in many cases, there was only casual physical contact, such as removing a bat from the house. Often, patients had no memory of a bat encounter at all.
If the animal can't be found, your doctor will ask questions to get a better sense of your risk of rabies. You'll be asked to describe the encounter: What type of animal was it, and did it bite unprovoked? If your doctor thinks you're at risk for rabies, treatment will start immediately.
Fortunately, the days of getting a series of dozens of rabies shots straight into the stomach are long gone, but there's still no magic pill. If you have not had rabies shots before, you will get a series of five injections over the course of four weeks, typically in the arm (or for children, in the thigh). It takes seven to 10 days to produce an immune reaction, and immunity lasts about two years. If you've had any rabies shots in the past, you may receive only two injections.
You may also receive a single shot of rabies immune globulin that will give you immediate antibodies to fight the infection because once the rabies virus enters the nerves and starts to travel towards the brain, the immune system isn't able to fight it. This shot will be given near the bite mark. If you've been vaccinated for rabies before, you may not need the immune globulin shot but should still get a series of two vaccine injections.
It's extremely rare to catch rabies from another person. The only documented cases in this country were from organ transplants. Still, health-care workers treating a person with suspected rabies should take standard precautions such as wearing protective clothing and masks. Close contacts such as friends and relatives do not require treatment, unless they were bitten by the patient or exposed to the patients saliva through a skin abrasion or contact involving the mucous membranes.
What can be done to reduce exposure to rabies?
The best way to reduce exposure to rabies is to stay away from wild animals, especially raccoons, bats, skunks, and foxes.
If you live in an area with bats, there are ways to prevent them from entering your rooms. If a bat does get into your house, call your local animal control or wildlife agency instead of trying to get rid of it yourself. If a bat flies in the window of a child's room at night or wakes you while you are sleeping, call animal control and get the bat captured and tested for rabies. If it's positive then anyone sleeping in the same room with the bat will need rabies shots. Even if you don't catch the bat, your doctor might advise you to get the shots, just in case.
That said, it's unlikely you'll catch rabies just by being near bats or other animals -- as long as you don't get bitten, a trip through a forest or cave where bats live shouldn't cause any trouble.
You should be careful with domestic animals, too. Although pets and domesticated animals are now required by law to receive rabies vaccinations, they can still be bitten and infected by wild animals. If your vaccinated pet has been exposed to a rabid animal, he should receive veterinary care right away. He will probably be re-immunized and kept under observation for several months. You should also report stray animals to your local animal control department, especially if they seem sick or are acting strangely. Keep up-to-date on rabies vaccinations for your own pets, including cats, dogs, and ferrets.
People who handle animals, like veterinarians, zookeepers, and animal scientists may need preventive vaccination involving three shots over one month, along with booster shots over the years to maintain the vaccinations effectiveness.
If you're traveling to a part of the world where rabies is still common and you're likely to come in close contact with wild animals, your doctor may recommend a preventive series of the rabies vaccine before you go. You should always keep your distance from dogs in developing countries. Even if you're up on your shots, you can bet they aren't up on theirs.
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