Rabies (pronounced /ˈreɪbiːz/. From ) or hydrophobia is a viral neuroinvasive disease that causes acute encephalitis (inflammation of the brain) in warm-blooded animals. It is zoonotic (i.e. transmitted by animals), most commonly by a bite from an infected animal, but occasionally by other forms of contact. It is fatal if left untreated. In some countries it is a significant killer of livestock.

The rabies virus makes its way to the brain by following the peripheral nerves. The incubation period of the disease depends on how far the virus must travel to reach the central nervous system, usually taking a few months. Once the infection reaches the central nervous system and symptoms begin to show, the untreated infection is usually fatal within days.

In the beginning stages of rabies, the symptoms are malaise, headache, and fever, while in later stages it includes acute pain, violent movements, uncontrolled excitements, depressions, and the inability to swallow water (hence the name hydrophobia). In the final stages, the patient begins to have periods of mania and lethargy, and coma. Death generally occurs due to respiratory insufficiency.

Etymology

The term is derived from the Latin rabies, "madness". This, in turn, may have come from the Sanskrit rabhas, "to do violence". The Greeks derived the word "lyssa", which is derived from "lud" or "violent", this terminology is used in the name of the genus of rabies lyssavirus.

Virology

main: Rabies virus

The rabies virus is the type species of the Lyssavirus genus, which encompasses other similar viruses. Lyssaviruses have helical symmetry, with a length of about 180 nm and a cross-sectional diameter of about 75 nm. These viruses are enveloped and have a single stranded RNA genome with negative-sense. The genetic information is packaged as a ribonucleoprotein complex in which RNA is tightly bound by the viral nucleoprotein. The RNA genome of the virus encodes five genes whose order is highly conserved. These genes are nucleoprotein (N), phosphoprotein (P), matrix protein (M), glycoprotein (G) and the viral RNA polymerase (L).

From the point of entry, the virus travels quickly along the neural pathways into the central nervous system (CNS), and then further into other organs. The salivary glands receive high concentrations of the virus thus allowing further transmission.

Transmission

main: Rabies transmission

Any warm-blooded animal, or human may become infected with the rabies virus and develop symptoms. If human, the infected human will become taken over by vicious animal symptoms. Which will cause bitting other people and too infecting that person. Rabies has no treatment. The only known way to stop rabies is to kill the infected person, or animal.). Indeed the virus has even been adapted to grow in cells of poikilothermic vertebrates though natural transmission has only been documented among mammals.Fact: date=April 2009 Most animals can be infected by the virus and can transmit the disease to humans. Infected bats, monkeys, raccoons, foxes, skunks, cattle, wolves, dogs, mongoose (normally yellow mongoose) or cats provide the greatest risk to humans. Rabies may also spread through exposure to infected domestic farm animals, groundhogs, weasels, bears and other wild carnivores. Rodents (mice, squirrels etc) are seldom infected.