Rabies is an acute viral disease, manifesting on the central nervous system and routinely transmitted to humans through a bite from an infected animal. The rabies virus is an RNA rhabdovirus from the Rhabdoviridae family.
The virus is contained in the saliva of an animal with rabies and is introduced into the skin through a bite or, much more rarely, through a recent skin abrasion. Airborne spread has been demonstrated in caves where numerous bats live.
The virus, after having infected the nervous system of wild and domestic animals, is present in the saliva of the sick animal even before the onset of symptoms and can be transmitted through a bite or contact with the saliva of the animal infected with the mucous. The incubation period varies widely from 2 weeks to one year, depending on the species affected, the inoculation point and the amount of virus inoculated.
The presence and spread of rabies in Europe is linked in particular to foxes, but other wild animals (badgers, martens, wild herbivores) are also involved to a lesser extent. When animals are affected by the disease their behaviour changes; wild animal lose their natural distrust of humans, domestic animals can become aggressive, with problems walking, paralysis and finally death.
Symptoms and complications
The virus, after multiplying around the inoculation point, spreads following the peripheral nerve fibres to the spinal cord and subsequently reaches the brain. The incubation period is generally 3 to 8 weeks. During incubation there may be symptoms including pain at the wound site, a sense of uneasiness, motor agitation, hallucinations, and hydrophobia (aversion to water) due to painful spasmodic contractions of the larynx and pharynx, followed by drowsiness, fever, collapse, and death. Diffuse, symmetrical paralysis sometimes develops. Without therapeutic interventions, death occurs in about 6 days, usually due to respiratory paralysis.
Impact on the population
Rabies is a disease found all over the world, with an estimated 65,000-87,000 deaths a year, almost all in developing countries, particularly in Asia (with an estimated number of deaths of 38,000-60,000) and in Africa (27,000 deaths). Most deaths in humans result from a rabid dog bite, which was not followed by adequate prophylaxis. In Italy, the last case of rabies reported in humans was a case imported from Nepal in 1996.
In February 1996 a case of human rabies was recorded in Veneto. A 32-year-old man travelling with his wife in Nepal was bitten by a stray pup on 21 January 1996. The doctor consulted in the city of Pokara (Nepal), after examining the patient's vaccination status for tetanus, did not consider it necessary to recommend any treatment apart from cleaning and disinfecting the wound. Approximately 30 days after the bite, the man suffered symptoms of high fever accompanied, starting from February 23rd, by laryngeal spasms and hydrophobia (aversion to water). His death occurred on February 25th, one day after admittance to the Hospital for Infectious Diseases in Venice.
Sources / Bibliography
- Bartolozzi G. Vaccini e vaccinazioni. Edizioni Masson Seconda edizione
- David L et. All Manuale per il Controllo delle Malattie Trasmissibili
- Ministero della Sanità Dipartimento della Prevenzione Malattie infettive e profilassi internazionale Osservatorio Epidemiologico Nazionale
- Ministero della Salute
- Signorelli C. Igiene Epidemiologia Sanità Pubblica .Società Editrice Universo IV edizione 2008