Rabies

Rabies is a viral zoonosis found in domestic and wild animals. It is transmitted to other animals or to human beings in saliva (for example from bites, scratches or licking onto excoriated skin or through the mucosal membranes). Once the symptoms of the disease develop it is fatal in both animals and human beings.

The initial symptoms are generally relatively non-specific and suggest respiratory digestive or central nervous system disease. In the acute stages, the predominant signs are of severe agitation (furious rabies) or paralysis (paralytic rabies). In both forms the paralysis ultimately becomes complete leading to coma and invariably to death usually due to respiratory failure. Without intensive care death occurs within the first seven days of the disease.

Transmission

The main reservoir hosts for rabies nowadays in developed countries are wild animals, from which the disease spreads to domestic animals and human beings. Bats have recently emerged as an epidemiological important reservoir in some regions of the world (the Americas and Australia). Most documented fatal cases of rabies in human beings in North America have followed infection from a strain of virus from the silver-haired bat and at least two deaths in human beings have been reported in Australia following exposure to an as yet unknown rabies virus. Rabies has been increasing in wild animals in South America, particularly bats. There were more deaths from rabies following wild animal bites than after dog bites for the first time on this continent in 2003. Nevertheless, wild animals remain the main host in Africa and Asia responsible for deaths from rabies and throughout the world too.

Rabies is usually transmitted to human beings by a bite from an infected animal: dogs, cats, wild carnivores such as foxes, raccoons, skunks, jackals, wolves, or otherwise insect-eating or vampire bats. Cattle, horses, sheep, and goats and other herbivores can contract rabies although the virus is only transmitted to other animals or human beings and although this can occur, it does so rarely.

Treatment after exposure

The most effective way of protecting against rabies is washing and rinsing the injury or contact point with soap and water, using a detergent or just water and then applying ethanol or iodine (in a tincture or aqueous solution). In category 2 and 3 exposures the anti-rabies vaccine must be administered as early as possible and following the WHO recommended protocols. Anti-rabies immunoglobulins must be administered after any category 3 exposure and after category 2 exposure in immunodeficiency. Wound suturing can be deferred although if it is essential, initially immunoglobulins should be applied. Where appropriate, anti-tetanus treatment is given and antimicrobials or other medicines are administered to combat infections other than rabies.

The use of highly purified equine immunoglobulins should at least bring a partial solution to the problems of cost and supply of human immunoglobulins. More details about pre- and post- exposure treatments can be found in the WHO guidance notes on post-exposure treatment of rabies.

If a human being is exposed to an animal suspected of having rabies, the animal should be identified immediately, captured or killed. In category 3 exposure, treatment must be started as soon as possible after exposure and can be stopped if the animal is a cat or dog and still healthy after 10 days. Tissue samples are taken from dead animals and sent for diagnosis to accredited laboratories. The veterinary services involved must be notified and information must be obtained about the epidemiological situation in the region.