West NIle virus is a misquito born virus, and it does effect humans. Symptoms may include fever, headaches, feeling tired, muscle pain or aches, nausea, loss of appetite, vomiting, and rash. Less than 1% of the cases are severe and result in neurological disease this is when the central nervous system is affected.
The symptoms may not show up for up to 15 days, so this makes this a very contagious disease, especially in warmer, moist areas. currently there is no vacination, except for antibiotics. In sever cases, people need to be hospitalised and given supportive treatment, such as intravenious fluids, nursing care, and sometimes pain medication.
Here is a map of the reported cases in the USA