Most people bitten by WNV- infected mosquitoes do not get sick. However, the elderly and people with weakened immune systems are more prone to infections. Symptoms begin 3-15 days after the bite from an infected mosquito. Symptoms may include fever, headache, nausea, rash, stiff neck, muscle weakness, and disorientation. The natural cycle of WNV involves birds and mosquitoes.
Mosquitoes acquire the virus from biting an infected bird.
The infected mosquito is then able to transmit the infection to healthy birds, horses or humans. Encephalitis is sometimes transmitted from adult female mosquitoes to their eggs. Some bird species display no symptoms while other species may get sick and die, notably crows. Not all sick or dead birds will have the disease and there is no evidence that people can contract WNV directly from either live or dead birds. Several species of mosquitoes in Rhode Island can transmit WNV from birds to humans.