NewsDesk @bactiman63

Arboviruses are zoonoses caused by viruses transmitted by arthropod vectors (arthropod-borne viruses, such as mosquitoes, ticks and sandflies) by bite/sting. They affect both humans and animals. At present there are over 100 viruses classified as arboviruses, capable of causing disease in humans. In Italy, arboviruses can cause both imported and locally transmitted (autochthonous) infections and can cause diseases with different clinical manifestations.


In Italy, the following arboviruses are subject to special surveillance: Chikungunya, Dengue, Zika, West Nile, Usutu, Tick encephalitis (TBE) and the neuro-invasive infections by Toscana virus, with West Nile currently the most widespread.

The confirmed cases of West Nile Virus (WNV) infection in humans in Italy have risen to 133 since the beginning of May; of these 74 manifested themselves in the neuro-invasive form (13 Piedmont, 20 Lombardy, 10 Veneto, 26 Emilia-Romagna, 2 Puglia, 1 Sicily, 1 Sardinia) 1 case imported from Hungary, 36 cases identified in blood donors ( 6 Piedmont, 23 Lombardy, 1 Veneto, 6 Emilia-Romagna), 23 cases of fever (5 Piedmont, 8 Lombardy, 8 Veneto, 2 Emilia-Romagna). Among the confirmed cases, 6 deaths were notified (2 Piedmont, 3 Lombardy, 1 Emilia-Romagna). The first human case of WNV infection of the season was reported from Emilia-Romagna in July in the province of Parma. In the same period, 2 cases of Usutu virus were reported in Piedmont (1 Novara, 1 Cuneo).

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West Nile fever is a disease caused by the West Nile virus (West Nile Virus, WNV), a virus of the Flaviviridae family isolated for the first time in 1937 in Uganda, precisely in the West Nile district (from which it takes its name). The virus is widespread in Africa, Western Asia, Europe, Australia and America.

The reservoirs of the virus are wild birds and mosquitoes (most frequently of the genus Culex), whose bites are the main means of transmission to humans. Other documented means of infection, though much rarer, are organ transplants, blood transfusions, and mother-to-fetus transmission during pregnancy. West Nile fever is not transmitted from person to person through contact with infected people. The virus also infects other mammals, especially horses, but in some cases also dogs, cats, rabbits and others. In Italy for several years now, a few dozen cases of West Nile have occurred in the summer period (up to a few hundreds in the years with higher incidence), transmitted by mosquito bites, while no cases of transmission by transfusion or transplant have ever been documented.

The incubation period from the moment of the bite of the infected mosquito varies between 2 and 14 days, but can be as long as 21 days in subjects with deficits in the immune system. Most infected people show no symptoms. Among the symptomatic cases, about 20% have symptoms such as fever, headache, nausea, vomiting, enlarged lymph nodes, skin manifestations. These symptoms can last a few days, in rare cases a few weeks, and can vary greatly depending on the age of the person. A mild fever is more frequent in children, while in young people the symptomatology is characterized by a moderately high fever, redness of the eyes, headache and muscle pain. In the elderly and in debilitated people, however, the symptoms can be more serious. The most serious symptoms occur on average in less than 1% of infected people (1 in 150 people) and include high fever, severe headache, muscle weakness, disorientation, tremors, vision disturbances, numbness, convulsions, up to paralysis and coma. Some neurological effects may be permanent. In the most severe cases (about 1 in a thousand) the virus can cause lethal encephalitis.