West Nile: Why it's called that, the symptoms, and how it's transmitted

West Nile disease (WND) is caused by an RNA virus belonging to the Flaviviridae family, Flavivirus genus, called West Nile Virus (WNV); the disease is generally transmitted to people and animals through the bite of infected mosquitoes of the Culex genus.

Why is it called West Nile?

The virus was first isolated in 1937 in Uganda from the blood of a woman with feverish symptoms from the West Nile district (hence the name West Nile disease). It is currently widespread in Africa, the Middle East, North and South America, Western Asia, and Europe, where it has been reported since 1958.

How it is transmitted

A flyer containing measures to prevent West Nile virus, the virus that is alarming Italy, was produced by the Campania Region and posted on the regional civil protection agency's social media pages.

The flyer states that "West Nile Disease (WND) is caused by a virus that lives in wild birds and can be transmitted through mosquito bites to mammals, birds, and reptiles. In rare cases, humans can contract the virus, but they cannot infect other people."

Incubation and symptoms

The incubation period from the moment of the bite of an infected mosquito varies between 2 and 14 days, but can be up to 21 days in subjects with immune system deficiencies.

Most infected people show no symptoms. Of those who do, about 20% have mild symptoms: fever, headache, nausea, vomiting, swollen lymph nodes, and skin rashes. These symptoms can last a few days, or in rare cases, a few weeks, and can vary greatly depending on the person's age. A mild fever is more common in children, while in young people, symptoms include moderately high fever, red eyes, headache, and muscle aches. In the elderly and debilitated, however, symptoms can be more severe.

The most severe symptoms occur in an average of less than 1% of infected people (1 in 150) and include high fever, severe headache, muscle weakness, disorientation, tremors, visual disturbances, drowsiness, convulsions, and even paralysis and coma. Some neurological effects can be permanent. In the most severe cases (about 1 in 1,000), the virus can cause fatal encephalitis.

How to prevent the spread of the virus

Here are some ways to prevent it : "Cover cisterns and containers where rainwater is collected with airtight lids, sheets, or mosquito nets; use insect repellent outdoors; treat manholes and rainwater drainage wells, drainage and stagnant areas with larvicides approximately every 15 days; screen doors and windows with mosquito nets; eliminate any shelters from buildings and homes where infected birds can nest; remove sources of stagnant water and change the water in animals' bowls frequently; check that gutters are clean and not blocked; keep children's pools empty and covered when not in use." Finally, some recommendations : "If you have any of the symptoms mentioned, contact your doctor or pediatrician. If you find dead birds, call the regional civil protection number 800232525."