West Nile virus is a mosquito-borne infection transmitted primarily by Culex mosquitoes. The virus circulates between mosquitoes and infected birds, with people becoming infected through mosquito bites.
Most people who contract West Nile virus do not develop symptoms. Around 80% remain asymptomatic, while approximately 20% experience a mild illness. Fewer than 1% develop serious neurological disease, which can be life-threatening.
Symptoms and severity
About 80% of infected people show no noticeable symptoms.
Around 20% develop a mild, flu-like illness. Symptoms can include fever, headache, muscle and joint pain, vomiting, diarrhoea and a mild skin rash.
In rare cases, West Nile virus can cause severe neurological disease, including encephalitis or meningitis. Warning signs may include high fever, a stiff neck, confusion, disorientation, tremors, seizures, muscle weakness or paralysis.
Older people and those with weakened immune systems are at greater risk of developing severe disease.
How is West Nile virus transmitted?
West Nile virus is mainly spread through the bite of an infected mosquito.
Rare forms of transmission include blood transfusions, organ transplants and transmission from mother to child during pregnancy or breastfeeding.
The virus does not normally spread through casual contact between people.
Treatment and prevention
There is currently no specific antiviral treatment for West Nile virus and no human vaccine routinely available.
Treatment focuses on relieving symptoms and providing supportive care. People who develop severe neurological disease may require hospitalisation and intensive medical treatment.
The risk of infection can be reduced by limiting exposure to mosquitoes. Health authorities recommend using approved insect repellents, wearing long sleeves and trousers, particularly around dawn and dusk, and removing standing water where mosquitoes can breed.
Window and door screens, as well as air conditioning, can also help keep mosquitoes out of homes.
Also read: 74-year-old man in critical condition with West Nile virus
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