Rabies
Rabies is a viral illness spread via the
saliva of an infected animal. This occurs usually through biting a human or
another animal. Transmission can also occur through saliva touching an open
wound or touching mucous membranes. In the United States,
between 1 and 3 people contract rabies each year. From 2008 to 2017, the
U.S. saw 23 human cases, eight of which were contracted outside the country.
Advances in medicine, awareness, and vaccination programs have reduced the
incidence of rabies since the 1970s. However, globally, it remains a problem, and tens of thousands of deaths result from rabies
each year, mostly in rural areas of Southeast Asia and Africa. Over 95 percent
of infections are caused by dogs.
Symptoms
The first
symptoms of rabies may be very similar to the flu and may last for days. Later
signs and symptoms may include:
·
Fever
·
Headache
·
Nausea
·
Vomiting
·
Agitation
·
Anxiety
·
Confusion
·
Hyperactivity
·
Difficulty
swallowing
·
Excessive
salivation
·
Fear
of water (hydrophobia) because of the difficulty in swallowing
·
Hallucinations
·
Insomnia
·
Partial
paralysis
Cause
Rabies is
caused by the rabies virus. The virus infects the brain and ultimately leads to
death. After being bitten by a rabid animal, the virus is deposited in the
muscle and subcutaneous tissue. For most of the incubation period (which is
usually one to three months), the virus stays close to the exposure site. The
virus then travels via peripheral nerves to the brain and from there, again via
peripheral nerves, to nearly all parts of the body.
Any
mammal can spread rabies. In the United States, rabies is most often
transmitted via the saliva of bats, coyotes, foxes, raccoons, and skunks. In
the developing world, stray dogs are the most likely animal to transmit rabies.
The virus has also been found in cows, cats, ferrets, and horses.
The local
health department will usually have information on which animals in the area
have been found to carry the rabies virus.
Transmission
Rabies is
most common in countries where stray dogs are present in large numbers, especially
in Asia and Africa. It is passed on through saliva. Rabies can develop if a
person receives a bite from an infected animal, or if saliva from an infected
animal gets into an open wound or through a mucous membrane, such as the eyes
or mouth. It cannot pass through unbroken skin.
In the
U.S., raccoons, coyotes, bats, skunks, and foxes are the animals most likely to
spread the virus. Bats carrying rabies have been found in all 48 states that
border with each other. Any mammal can harbor and transmit the virus, but
smaller mammals, such as rodents, rarely become infected or transmit rabies.
Rabbits are unlikely to spread rabies.
Risk factors
Factors
that can increase your risk of rabies include:
·
Traveling
or living in developing countries where rabies is more common, including
countries in Africa and Southeast Asia.
·
Activities
that are likely to put you in contact with wild
animals that may have rabies, such as exploring caves where bats live or camping
without taking precautions to keep wild animals away from your campsite.
·
Working
in a laboratory with the rabies virus.
·
Wounds
to the head or neck, which may help the rabies virus travel to your brain more
quickly.
Diagnosis
At the
time of a bite, there is usually no way to tell for sure whether an animal is
rabid, or whether it has passed on an infection. Lab tests may show antibodies,
but these may not appear until later in the development of the disease. The
virus may be isolated from saliva or through a skin biopsy. However, by the
time a diagnosis is confirmed, it may be too late to take action. For this
reason, the patient will normally start a course of prophylactic treatment at
once, without waiting for a confirmed diagnosis. If a person develops symptoms
of viral encephalitis following an animal bite, they should be treated as if
they may have rabies.
Treatment
If a
person is bitten or scratched by an animal that may have rabies, or if the
animal licks an open wound, the individual should immediately wash any bites
and scratches for 15 minutes with soapy water, povidone
iodine, or detergent. This might minimize the number of viral particles.
Then they
must seek medical help at once.
After
exposure and before symptoms begin, a series of shots can prevent the virus
from thriving. This is usually effective.
Prevention
To reduce
your risk of coming in contact with rabid animals:
Vaccinate your pets. Cats, dogs and ferrets can be
vaccinated against rabies. Ask your veterinarian how often your pets should be
vaccinated.
Keep your pets confined. Keep your pets inside and
supervise them when outside. This will help keep your pets from coming in
contact with wild animals.
Protect small pets from predators. Keep rabbits and other small
pets, such as guinea pigs, inside or in protected cages so that they are safe
from wild animals. These small pets can't be vaccinated against rabies.
Report stray animals to local
authorities. Call your local animal control
officials or other local law enforcement to report stray dogs and cats.
Don't approach wild animals. Wild animals with rabies may
seem unafraid of people. It's not normal for a wild animal to be friendly with
people, so stay away from any animal that seems unafraid.
Keep bats out of your home. Seal any cracks and gaps where
bats can enter your home. If you know you have bats in your home, work with a
local expert to find ways to keep bats out.
Consider the rabies vaccine if
you're traveling.
If you're traveling to a country where rabies is common and you'll be there for
an extended period of time, ask your doctor whether you should receive the
rabies vaccine.