It is possible that dogs and cats could become infected by eating dead infected animals such as birds, but this is unproven. The extent to which West Nile virus is present in wild game is unknown. The chances that any one bite will be from an infected mosquito are very small. Even if you are bitten by an infected mosquito, your chances of developing illness are roughly one in 150 to one in 300. Symptoms West Nile virus can cause a spectrum of illness which ranges from no symptoms to mild illness to fatal encephalitis.
Most infections are mild.
Symptoms in humans include fever, headache, and body aches, often accompanied by skin rash and swollen lymph glands. More severe infections may include high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness and paralysis. Although rare, WNV can cause death in humans. At its most serious, it can cause permanent neurological damage and can be fatal. Once infected by a mosquito, the virus multiples in the blood and crosses the blood-brain barrier to reach the brain.