What is Anger?
Rabies is a highly lethal zoonosis (ie those affected often die) caused by a virus.
Like all zoonoses, rabies can be transmitted from animals to humans.
Anger affects practically all homeothermic vertebrates ("warm-blooded"), although animals with a well-developed dental apparatus (dogs, foxes) are generally most at risk, as the disease is transmitted mainly through the bite .
Rabies virus
The virus that causes rabies is an RNA virus, which is part of the order of the Mononegavirales ; it belongs to the Rhabdoviridae family and to the genus Lyssavirus . Of this we can recognize 7 genotypes (distinguished on the basis of genetic sequencing) and 4 serotypes (distinguished on the basis of neutralization serum, or with the use of antibodies). The most common serotype in Europe is type 1 (called street virus ), which affects both domestic and wild carnivores.
The virus responsible for rabies resists little outside the host (affected animal); in fact it turns out to be sensitive to different solvents, lipid detergents and sunlight. Furthermore, there are several disinfectants that can inactivate it, including quaternary ammonium salts, 7% iodophores and 1% soaps; these products can also be applied directly to wounds as a first intervention after a bite from a suspect animal.
Contagion
The transmission of the virus occurs mainly through the bite of the infected animal to the healthy one, as the pathogen is localized in the salivary glands and is therefore eliminated with saliva.
Other modes of transmission of the disease (even if rare) can be represented by the contagion by aerosol (possible in closed environments and with a high concentration of the virus), or through the oral route (in this case, micro-lesions are necessary in the mouth as the virus if it reaches the stomach, it is inactivated by the acid pH).
Spread of Anger
Rabies is considered a worldwide disease. It is absent at the poles and in countries such as the United Kingdom, Finland, Sweden, Greece, Norway, Switzerland, Denmark, Spain, Portugal and Italy (although in Veneto, Friuli and Trentino some cases of rabies have recently been found).
Potentially the virus can affect all warm-blooded animals (mammals and birds), but depending on the animal species involved, two different epidemiological (diffusion) cycles of rabies are distinguished: urban cycle and woodland cycle .
The urban cycle is identified among domestic animals (such as cats, but especially the dog) and finds in the phenomenon of stray dogs (dogs that live in the street and often come into contact also with wild animals) the main source of conservation and transmission of virus.
The sylvan cycle, on the other hand, sees different animal species involved in the transmission of the virus, depending on the geographical area concerned: in Europe we mainly have the fox (following rodents and bats ), which keeps the sylvatic rabies cycle active because it transmits the virus before that the symptoms appear, as the disease has a long incubation period (the period between the infection and the onset of symptoms); moreover, the fox is used to making large movements.
The mangosta represents the only reserve of Rabbia in the Caribbean area.
In Russia and the Middle East the reservoir is represented by the wolf, in the USA by coyote, in central / north America by bats and in South America by vampires ; in Africa, finally, the animal of Rabbia is the jackal .
How Anger develops
It has already been mentioned that, apart from the rare possibility of infection through inhalation or ingestion, biting represents the most frequent means of transmitting rabies.
The infected animal, through biting, transfers the virus to the healthy animal being bitten with saliva.
Generally, the penetration point of the virus (corresponding to the point where it is bitten) is a limb, or in any case an area rich in muscles where there is, for a short time, an initial replication of the pathogen.
Subsequently the rabies virus migrates mechanically, through the structures that innervate the affected muscle (the extensions of the neurons that together form the nerve), to reach the spinal cord. From here, after further replication, it reaches the brain. This phase of the infection is called the centripetal migration of the virus, because from the periphery (penetration point), it reaches the central level (brain).
At this point the so-called centrifugal migration begins: that is, the rabies virus, which is localized in the brain, through the nerve that terminates on the salivary glands, reaches them, replicating itself massively. Having reached this stage, the animal, even if it does not show obvious symptoms, can already eliminate the rabies virus with saliva.
To conclude, the virus then spreads to the entire central nervous system, causing paralytic phenomena that will lead to death by asphyxia (impediment to normal respiratory functions), consequent to respiratory paralysis.
