Nile Fever does not usually cause particular problems, but in some cases it can be extremely dangerous
In recent days, the cases of West Nile Virus infection (the name of the virus comes from the area where it was first isolated, that is from the West Nile district in Uganda) that occurred in Italy have caused a sensation. The infection often does not cause particular problems, but in some cases it can be extremely dangerous: it is transmitted through mosquito bites, while human-to-human infection is not possible.
The disease, which has an average incubation ranging from five days to two weeks, is caused by a virus of the flavivirus family: these strains are known for their ability to attack the central nervous system, in particular the brain, so much so that be responsible for Japanese encephalitis and other similar diseases.
The pathogen passes to humans and other animals – such as horses – through the bite of the mosquito. It can spread mainly through migratory birds, which are bitten by insects and carry the virus inside them. Once pinched by mosquitoes, these animals can then release the virus, which in turn is transmitted to a new host.
Mosquitoes then become infected by contact with infected birds, which can circulate the virus in their blood for a few days. Infected insects can transmit West Nile virus to humans and animals, which become the virus's "terminal" hosts when mosquitoes bite to draw blood and feed.
The virus resides in the salivary glands of the mosquito: while these suck blood, they can inject it into animals or humans, where it multiplies and, consequently, lead to disease. Infection from animal to animal does not occur, while transmission between humans, in theory, could only occur in very few cases, such as after an organ transplant.
Remember the flu
Nile fever in humans has an average incubation ranging from five days to two weeks and can have very different manifestations from case to case.
In most cases it begins as a very common parainfluenza syndrome, with fever, headache and muscle aches that tend to go away on their own in a few days. The involvement of the lymphatic glands is also quite common, as well as localized redness of the skin.
Only in some people, especially in the elderly, can the infection lead to encephalitis, which can be fatal or even leave neurological problems as a "legacy" of contact with the virus.
In these cases, the clinical picture is very different: severe headaches, neck stiffness (similar to that of meningitis), muscle weakness and loss of consciousness may be present. The fever is almost always very high and remains so for several days.
However, this is a generally uncommon picture: according to some statistics, less than one person in a hundred of those infected develops encephalitis. On the treatment front, there is no specific antiviral treatment: hospitalization is essential in forms with encephalitis, because it is necessary to support breathing, ensure adequate nutrition and prevent secondary infections, possibly caused by potentially fatal bacteria. In a preventive key, unfortunately there is still no specific vaccine.