Saturday, August 29, 2009
What Is The Rabies Disease
Rabies is a disease humans may get from being bitten by an animal infected with the rabies virus. Rabies has been recognized for over 4,000 years. Yet, despite great advances in diagnosing and preventing it, today rabies is almost always deadly in humans who contract it and do not receive treatment.
Rabies can be totally prevented. You must recognize the exposure and promptly get appropriate medical care before you develop the symptoms of rabies.
Where rabies is found: Human rabies is quite rare in the United States. Only 27 cases have been reported in people in the United States since 1990. Yet in some areas of the world (for example, Southeast Asia, Africa, and Latin America), human rabies is much more common.
The incidence of rabies in people parallels the incidence in the animal kingdom. The great strides that have been made in controlling the disease in animals in the United States and in other developed countries is directly responsible for this decline in human rabies.
Although rabies in humans is very rare in the United States, between 16,000 and 39,000 people receive preventive medical treatment each year after being exposed to a potentially rabid animal. Some regions of the country have more cases of rabies than others do. Rabies in wildlife accounts for greater than 85% of animal rabies in the United States.
Animals that carry rabies: Raccoons are the most common wild animals infected with rabies in the United States. Skunks, foxes, bats, and coyotes are the other most frequently affected.
Bats are the most common animals responsible for the transmission of human rabies in the United States, accounting for more than half of human cases since 1980, and 74% since 1990. Rabid bats have been reported in all states except Hawaii.
Cats are the most common domestic animals with rabies in the United States. Dogs are the most common domestic rabid animals worldwide. Almost any wild or domestic animal can potentially get rabies, but it is very rare in small rodents (rats, squirrels, chipmunks) and lagomorphs (rabbits and hares). Large rodents (beavers, woodchucks/groundhogs) have been found to have rabies in some areas of the United States. Additionally, fish, reptiles, and birds are not known to carry the rabies virus.
For a human to get rabies, 2 things must happen. First, you must have contact with a rabid animal. Second, the contact must allow for the transmission of infected material, which will involve exposure to the saliva of the infected animal usually through a bite or scratch.
Contaminated tissue in the rabid animal includes saliva. Other potentially infectious tissue is in the brain or nerve tissue. The virus is transmitted only when the virus gets into bite wounds, open cuts in your skin, or onto mucous membranes (for example, into your eyes or your mouth). The virus then spreads from the site of the exposure to your brain and eventually spreads throughout your body's major organs.
Moreover, bites are the most common source of transmission. Scratches by infected animals are far less likely to cause infection but are still considered a potential source of rabies transmission. Bites or scratches are often not confirmed in cases of human rabies traced to bats. Therefore, treatment might be necessary after a close encounter with a bat.
In the 20 cases (since 1990) of human rabies associated with a bat, a definite history of a bat bite could be confirmed in only 1 case. It is unclear how the virus was transmitted in the other cases perhaps by an undetectable bite.
Rabies has rarely been transmitted by other means. Examples include inhaling a large amount of bat secretions in the air of a cave by 2 cave explorers and inhaling the concentrated virus in laboratory workers studying rabies.
Animals infected with rabies may appear sick, crazed, or vicious. This is the origin of the phrase "mad dog." However, animals infected with rabies may also appear overly friendly, docile, or confused. They may even appear completely normal.
Seeing a normally nocturnal wild animal during the day (for example, a bat or a fox) or seeing a normally shy wild animal that appears strange or even friendly should raise suspicion that the animal may have rabies.
Furthermore, the average incubation period (time from infection to time of development of symptoms) in humans is 30-60 days, but it may range from less than 10 days to several years.
Most people first develop symptoms of pain, tingling, or itching shooting from the bite site (or site of virus entry). Nonspecific complaints of fevers, chills, fatigue, muscle aches, and irritability may accompany these complaints. Early on, these complaints may seem like any virus, except for the shooting sensations from the bite site. Gradually, however, you will become extremely ill, developing a variety of symptoms, including high fever, confusion, agitation, and eventually seizures and coma.
Typically, people with rabies develop irregular contractions and spasms of the breathing muscles when exposed to water (this is termed hydrophobia). They may demonstrate the same response to a puff of air directed at them (termed aerophobia). By this point, they are obviously extremely ill. Eventually, the various organs of the body are affected, and the person dies despite support with medication and a respirator.
A rarer form of rabies, paralytic rabies, has been linked to vampire bat bites outside of the United States. In this form, the person who was bitten develops a paralysis, or inability to move the part of the body that was bitten. This spreads gradually throughout the body, and the person ultimately dies. Hydrophobia is less common in paralytic rabies than in classic rabies.
By. Alisha Dhamani
Posted by Timotius Budiman at 12:02 AM