The West Nile virus is a mosquito-borne virus that can cause a wide variety of diseases in the human body. The virus currently has no vaccine, with over 75% of infected people having little or few symptoms. The most common symptoms include fever, headache, vomiting or rashes. In rare cases, diseases such as encephalitis or meningitis may occur, with seizures, delirium and neck stiffness being associated with the disease. The virus was first detected in Uganda in 1937.
The virus is usually carried by infected mosquitoes who themselves become carriers while feeding on infected birds. It is rarely transmitted through blood transfusions, organ transplants or from the mother to the baby during pregnancy and breastfeeding. The disease is usually diagnosed on the basis of symptoms and blood tests. It is common to large parts of the world including Africa, the Middle East, India, South-East Asia, Europe and North America.