West Nile virus spreads when a mosquito bites an infected bird and then bites a person, researchers suggest. Culex Pipiens and Culex perexiguus have been the main mosquitoes which help in spreading of the virus.

The count of the West Nile virus affected cases has been less as compared to the previous years. The reason could be the cool temperature of the month of June which does not suits the mosquitoes. However, the mosquito season may continue till the end of autumn season this year.

The symptoms of the virus could be like of mild temperature that includes fever, headaches, weakness, joint and muscle pain, rashes, conjunctivitis around the eyes, and diarrhea and nausea. Sometimes meningitis and encephalitis occur in rare cases.

No vaccine has been developed against the virus so the people with weak immune system should protect themselves from the mosquitoes. People with higher risk of infection should cover themselves with proper clothes and should apply insect repellent on exposed skin.

The District of Columbia Department of Health (DOH) stated, "Residents should take caution as mosquitoes have the potential to transmit West Nile Virus to humans, and it is important for residents to take the necessary steps to avoid contracting the virus".