The West Nile Virus causes the West Nile Encephalitis. The family that this virus belongs to also consists of viruses that cause other illnesses like Japanese encephalitis and the dengue fever. These viruses are known to be present primarily in birds; seventeen species of birds carry this virus. The Culex, Aedes, and Anopheles mosquitoes basically bite on and suck this infected blood from the birds and transmit the virus when they then bite a human being. Show More
Mosquitoes are responsible for transmitting this virus from birds to mammals. However, mammals do not make ideal hosts. The disease, because of this, seldom transmits from one human being to the other. Around 70-80 % of those who have this virus display no symptoms at all and about 20-25 % show symptoms of a fever. However, around 1 % of people with the West Nile Virus end up developing a neurological disease, or WNE.