Rabies: A Nearly 100 Percent Fatal, But Also Nearly 100 Percent Preventable, Viral Zoonotic Infection

So, you've heard of rabies, and you know it's bad — right? Many people will never have a real practical reason to find out more about this disease, but others will unfortunately have an up-close-and-personal encounter with rabies. For everyone else, it's always good to be familiar with the basics of such a dangerous infection.

What exactly is rabies — what does it do to the human body?

Rabies is a zoonotic viral infection, which means it is spread by certain mammals, in this case through the saliva a person can come into contact with when bitten by a rabid animal. The infection usually reaches the brain and spinal cord around 30 to 50 days after the bite, though this incubation period can also take a matter of days or be delayed as long as one whole year. Once rabies reaches this stage, it is fatal in nearly 100 percent of cases — only 14 people are reliably known to have survived rabies after symptoms appeared, ever.

The first rabies symptoms in humans include:

• Fever
• Headache
• General feelings of illness
• Increasingly bizarre behaviors, from restlessness to excitement, confusion, and behaviors related to the hallucinations they may also have.
• Excess saliva
• Spasms around the throat area that render a rabies victim unable to speak, eat, or drink.
• For some people, the symptoms of rabies start around the site of the animal bite, where they may feel tingling sensations followed by paralysis.

As the infection reaches the brain, seizures, paralysis, coma, extreme confusion and irritability, an inability to breathe, coma, and eventually death can be expected. 

Doctors will kick-start the diagnostic process for rabies if they notice a combination of symptoms that points to possible rabies, and though having been bitten by an animal would push rabies higher on the list of suspected diagnoses, it's essential to note that many people who develop rabies don't remember being bitten. Therefore, rabies cannot be ruled out in people who don't recall an animal bite.

The diagnostic process involves tests of the person's saliva, spinal fluid, and skin. In recent times, you will already have become familiar with the term "polymerase chain reaction (PCR)" test. This kind of test is also used to pinpoint the specific DNA of the rabies virus.

Which animals can spread rabies?

Only mammals are able to be infected with and spread rabies, and infected animals can pass the virus on only once they become symptomatic. The infection is usually spread though bites, but in much rarer cases, rabies can also be spread through other means, such as scratches. For this to happen, the infected animal's saliva has to reach a person's bloodstream.

Globally, 99 percent of rabies cases in humans are caused by rabid dogs, and most of those cases occur in Africa and Asia. In Europe, North America, and some Latin American countries, as well as Japan, rabies is almost never spread by dogs, however. In America, but not in Europe, bats are the cause of most human deaths to rabies. Wild animals are most likely to spread rabies in developed nations, and these animals include raccoons, foxes, skunks, and ferrets.

Signs of rabies in animals are similar to those also seen in humans:

• General malaise
• Excess saliva production, often noticeable to observers
• (Partial) paralysis
• Wild animals that seem friendlier than they should be but also those that attempt to bite everything warrant special caution

Rabies: A preventable infection

Pets and livestock that can get infected with rabies, such as cats, dogs, ferrets, and horses, should regularly be vaccinated for rabies. The fact that this vaccine is mandatory in modern countries explains why domesticated animals almost never get rabies there, but some efforts are now also being made in places like the US to vaccinate wild animals like raccoons, which quite often come into close contact with humans. When animals are vaccinated, rabies cases will rapidly dwindle. 

Pet owners should make efforts to keep their pets away from wild animals, or vice versa. All humans should also stay away from wild animals — a wild animal, like a fox, that seems to be friendly may seem cute and cuddly, but keep in mind that it could pose a fatal risk. If you observe this kind of thing, it's best to call your local health department or animal control. 

Humans who were bitten or scratched by a wild animal, or by any mammal exhibiting odd behavior, should seek immediate medical attention. If the animal's location is known, it too should be brought in for observation and testing. If the doctor believes that there is a chance you have been exposed to rabies, you will be given postexposure prophylaxis. This consists of immune globulin and four doses of rabies vaccine, given over the course of two weeks. 

Note that some bites, like bat bites, may be painless and not very obvious. This is another reason to see a doctor as soon as possible even if you aren't totally sure you were bitten — the sooner you get medical help, the easier it will be for your health care provider to look at your wound. 

Some people who have an especially high risk of contracting rabies should also get a preexposure vaccine. These people may include veterinarians, lab workers, people who often travel to regions of the world where there are many cases of rabies, and also wildlife or outdoor enthusiasts.