The most severe type of disease due to a person being infected with the West Nile virus is called "neuroinvasive disease" because it affects a person’s nervous system. It is characterized by:
- High Fever
- Neck Stiffness
- Stupor and Other Serious Symptoms
Symptoms can last weeks to months, and can even result in death. West Nile neuroinvasive disease (WNND) only infects approximately 1% of people who have been bitten by a West Nile fever (WNF) - carrying mosquito. West Nile fever is another type of illness that can occur in people who become infected with the virus. It is characterized by:
- Tiredness and Sometimes Rash
Although the illness can be as short as a few days, even healthy people have been sick for several weeks. WNF infects approximately 20% of people who have been bitten by a WNF - carrying mosquito.