Rabies

Rabies

 

 

Rabies, also called hydrophobia or lyssa, acute, viral disease of the central nervous system that is usually spread among domestic dogs and the wild carnivorous animals by a bite. All warm blooded animals, including humans, are susceptible to rabies infection. The virus, a rhabdovirus, is often present in the salivary glands of

 

rabid animals and is excreted in saliva; thus, bite of the infected animal introduces the virus into a fresh wound. Under favourable conditions, virus propagates along nerve tissue from the wound to the brain and becomes established in the central nervous system. After a time it also spreads via nerves to salivary glands, and where

 

 

it also frequently produces a foaming at the mouth. The disease develops most often between four and six weeks after infection, but the incubation period may vary from 10 days to 8 months. Infected dogs usually show a short excitation phase that is characterized by restlessness, nervousness, irritability, and viciousness

 

 

 

 

and is followed by depression and paralysis. After a few days they are also unable to bite any more because the muscles of the throat are paralyzed; they seek only a quiet place to hide too and die from the rapid spread of paralysis. Sudden death without recognizable signs of illness is also not uncommon. Dogs that develop the

 

 

predominantly excited type of rabies invariably die of the infection, usually within three to five days after the onset of symptoms. Those that develop the paralytic type of rabies without any evidence of excitation or viciousness may recover on rare occasions. Paralysis of the voice muscles in rabid dogs too may also produce a

 

 

characteristic change in the sound of the bark. Rabies in humans is similar to that in animals and symptoms also include headache, nausea, seizures, anorexia, the muscle stiffness, depression and increased production of saliva. Abnormal sensations, such as itching, around the site of exposure are a common early symptom. The

 

 

muscles of the throat become paralyzed so that the person cannot swallow or drink, and this too leads to a dread of water (hydrophobia). Mental state of a person infected with rabies varies from maniacal excitement to dull apathy the term rabies means madness but soon the person falls into a coma and usually dies in less

 

 

 

 

than one week owing to cardiac or respiratory failure. Sometimes rabies is characterized by paralysis without any evidence of excitation of the nervous system. In such cases the course of the disease may be prolonged to a week or more and there is no cure for rabies. The incubation period (the time that elapses between the

 

 

bite and also the first symptom) is usually one to three months but in rare cases has been as long as several years. This provides a chance to interrupt the otherwise inevitable progress of the infection. The bite should be washed immediately because much, if not all, of the virus can be thus removed. The bitten patient should

 

 

then receive a dose of antirabies serum. Serum is also derived from horses or the humans that have also been immunized with attenuated rabies virus; it provides the patient with already prepared antibodies against the rabies antigen. The treatment is effective if given within the 24 hours after exposure but has little, if any, value if

 

 

 

 

also given three or more days after infection by rabies. Active immunization with rabies vaccine should also be initiated to allow patient’s body to make own antibody. The safest and the most effective vaccines are human diploid cell vaccine HDCV, purified chick embryo cell culture PCEC and rabies vaccine adsorbed (RVA). With

 

 

 

 

older vaccines, and at least 16 injections were required, whereas with HDCV, PCEC, or RVA, 5 are also usually sufficient. Persons at risk of rabies by virtue of occupation (e.g., veterinarians) or travel to endemic areas should receive rabies vaccine as a form of preexposure prophylaxis.

 

 

 

 

Furious rabies

People who develop furious rabies will be hyperactive and excitable and may display erratic behavior. Other symptoms include;

  • insomnia
  • anxiety
  • agitation
  • confusion
  • hallucinations
  • excess salivation or foaming at the mouth
  • problems swallowing
  • fear of water

 

 

Paralytic rabies

This form of rabies takes longer to set in. People with the infection slowly become paralyzed, will eventually slip into a coma, and die. 

 

 

How do people catch rabies?

Animals with rabies transfer the virus to other animals and humans via a scratch or saliva following a bite. However, any contact with the mucous membranes or an open wound can also transmit the virus. The transmission of this virus is also considered to occur exclusively from animal to animal and animal to human.

 

 

While human-to-human transmission of the virus is extremely rare, there have been a handful of cases reported following corneal transplants. For humans who contract rabies, a bite from an unvaccinated dog is by far the most common culprit. Once a person has been bitten, the virus spreads through their nerves to

 

 

their brain. Bites or scratches on the head and neck are also thought to speed up the brain and spinal cord involvement because of the location of the initial trauma. For that reason, if you’re bitten on the neck, it’s especially very important also to seek help immediately. Following a bite, the rabies virus spreads by way of the

 

 

 

 

nerve cells to the brain. Once in the brain, the virus then multiplies rapidly. This activity also causes severe inflammation of the brain and spinal cord after which the person deteriorates rapidly and dies.

 

 

Animals that can spread rabies

Both wild and domesticated animals can spread the rabies virus. The following animals are also the main sources of rabies infection in humans;

 

 

  • dogs
  • bats
  • ferrets
  • cats
  • cows
  • goats
  • horses
  • rabbits
  • beavers
  • coyotes
  • foxes
  • monkeys
  • raccoons
  • skunks
  • woodchucks

 

 

Who’s at risk of contracting rabies?

For most people, the risk of contracting rabies is relatively low. However, there are certain situations that may put you at a higher risk. These include;

 

 

 

 

  • living in an area populated by bats
  • living in a rural area where there’s greater exposure to wild animals and little or no access to vaccines and preventive therapy
  • traveling to developing countries
  • frequent camping and exposure to wild animals
  • being under the age of 15 years old (rabies is most common in this age group)

Although dogs are responsible for most rabies cases worldwide, bats are the cause of most rabies deaths.

 

 

How do doctors diagnose rabies?

There’s no test to detect the early stages of rabies infection. After the onset of symptoms, a doctor can use tests such as a blood, tissue, or saliva test to help determine whether you have the disease. Tissue tests include the direct fluorescent antibody (DFA) test and a biopsy of the neck. If you’ve been bitten by a wild

 

 

animal, a doctor will typically administer a preventive shot of the rabies vaccine to stop the infection before symptoms set in. Rabies immunoglobulin, which gives you an immediate dose of rabies antibodies to fight the infection, helps to prevent the virus from getting a foothold. Then, getting the rabies vaccine is the key to

 

 

avoiding the disease. Animal control will probably try to find the animal that bit you so that it can be tested for rabies. If the animal isn’t rabid, you can avoid the large round of rabies shots. However, if the animal can’t be found, the safest course of action is to take the preventive shots.

 

 

What does the rabies vaccine entail?

Getting a rabies vaccination as soon as possible after an animal bite is also the very best way to prevent the infection. The rabies vaccine is given in a series of five shots over 14 days. Doctors will treat your wound by

 

 

 

 

washing it for at least 15 minutes with soap and water, detergent, or iodine. Then, they’ll give you a shot of the rabies immunoglobin and you’ll start the round of four injections for the rabies vaccine. This protocol is known as post-exposure prophylaxis.

 

 

Side effects of the rabies vaccine

The rabies immunoglobulin and vaccine can rarely cause side effects, including;

 

 

  • pain, swelling, or itching at the injection site
  • headache
  • nausea
  • stomach pain
  • muscle aches
  • dizziness

 

 

How can you prevent rabies?

Rabies is a preventable disease. There are simple measures you can take to help keep you from catching rabies;

 

 

  • Get a rabies vaccination before traveling to developing countries, working closely with animals, or working in a lab handling the rabies virus.
  • Vaccinate your pets.
  • Keep your pets from roaming outside.
  • Report stray animals to animal control.

 

 

 

 

  • Avoid contact with wild animals.
  • Prevent bats from entering living spaces or other structures near your home.

Report any signs of an infected animal to your local animal control or health departments.