A study of the 1999 outbreak in New York published in the Lancet on Friday shows that up to 13,000 people were infected. A similar infection rate in Florida's elderly population could have severe consequences since the elderly are much more susceptible to the disease caused by the virus.
Mosquitoes transmit the virus.
The analysis of the 1999 outbreak found that between 3500 people and 13,000 people, or an average of 2.6 per cent of the population in the area, were infected. Elderly and immuno-compromised people are most at risk of encephalitis, for which there is no cure or vaccine. A. Mosquitoes become infected when they feed on infected birds, which may circulate the virus in their blood for a few days. After an incubation period of 10 days to 2 weeks, infected mosquitoes can then transmit West Nile virus to humans and animals while biting to take blood. The virus is located in the mosquito's salivary glands.