How Do Animals And Humans Spread and Contract Rabies?

The vast majority of human rabies cases are contracted via bites from infected animals. If untreated, encephalitis develops and often leads to death,

What Is Rabies?

Rabies is a vaccine-preventable, yet deadly, viral disease that affects humans and other warm-blooded animals. The disease is caused by species of the lyssaviruses which include the rabies virus and the Australian bat virus. Rabies is a contagious disease that is spread from one animal to another or to humans via bites, scratches, or contacts with the saliva of another infected animal. If not treated in time, the disease is almost always fatal in nature. September 28th is celebrated as the World Rabies Day each year, and a day meant to raise awareness regarding the disease and the methods of preventing and eliminating the disease.

Signs and Symptoms

The incubation period of the rabies virus is usually 1 to 3 months, but this also may vary between the extremes of less than one week to more than one year. Several factors, such as the initial viral load at the time of infection and original site of viral entry, determines the incubation period of the virus. The initial response to the infection results in feeling pain or a tickling, burning sensation at the infection site, followed by a mild to high fever. If proper treatment is not received, usually within ten days of the infection's symptomatic onset, the virus starts spreading into the central nervous system (CNS), resulting in potentially fatal inflammation of the brain and spinal cord. Once the virus enters the CNS, it is almost impossible to eliminate the infection. Death follows, preceded by two types of symptoms. The patient might become hyperactive and exhibit excited behavior and "hydrophobia" (a fear of drinking and swallowing), and in some cases patients can develop aerophobia (a fear of flying or falling from heights). Death follows in a few days by way of cardiorespiratory arrest. In the other, less common cases, representing around 30% of the total human cases, the symptoms are less dramatic, wherein a gradual muscular paralysis sets in, followed by coma and then death.

How Common is Rabies in Humans?

Rabies exists in all of the continents of the world except for Antarctica. Usually, children below 15 years of age are most vulnerable to become victims of this disease. Though rabies occurs worldwide, 95% of rabies-related deaths occur in Asia and Africa. The most likely to die of this disease are people living in extreme poverty who are unable to afford the expensive post-exposure prophylactic treatment protocol, which costs as much as $40 USD in Africa and $49 USD in Asia, places where people living below the extreme poverty line may earn only $1 to $2 USD per day. Today, Rabies is most problematic in southern Africa, while many developed countries in East and Southeast Asia, the European Union, and Oceania are considered to be "rabies free".

Rabies Transmission

Rabies is a contagious diseases which affects all types of warm-blooded species, though it is more common in certain species of animals, including dogs, cats, bats, monkeys, wolves, raccoons, foxes, skunks, and mongooses. 99% of the cases of animal-to-human transmission of rabies involve dogs, especially children being bitten by rabid dogs. Rabies might also be spread to humans from cats, farm animals, groundhogs, and weasels. Bites or scratches by a symptomatic infected animal or contact with the saliva of such an animal might manifest in rabies in humans. Bites from mice, squirrels, rats, and other smaller animals, meanwhile, hardly signify a threat of rabies infection, as these are highly unlikely given that these animals rarely manage to survive an encounter with a larger rabid animal so as to act as carriers of this disease themselves. The transmission of rabies between humans is also rarely known to occur.

Prevention and Treatment

Rabies has an extremely high fatality rate, with almost no treatment options being available once the virus has hijacked a patient’s "brain machinery", thereafter initiating the full-blown symptoms of the disease. The first thing to do to prevent rabies is to wash a wound thoroughly immediately after a bite or scratch from a suspected rabid animal. This helps to decrease the viral load entering the bloodstream of an individual. There is also an immediate need to receive a prescribed dose of human rabies immunoglobulin and rabies vaccine in order to stop the multiplication of the rabies virus within the body. If this post-exposure prophylaxis is not administered to the victim, the rabies viral infection will almost surely develop, and likely claim the life of the individual. Even though rabies is highly lethal, hope was seen in 2004 when an American teenage girl from Wisconsin named Jeanna Giese survived rabies in the absence of any post-exposure prophylaxis treatment. After symptoms developed in her, she was put into a state of induced coma by an administration of anesthetics, and also kept under the treatment of antivirals. Surprisingly, like a miracle come true, she survived rabies, with only some movement difficulties after her recovery. This mode of treatment, now known as the Milwaukee protocol, has now been applied to treat many other patients who have developed rabies, and 5 of the 43 patients treated with this method have survived the disease.

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