New Orleans has confirmed a second case of neuroinvasive West Nile virus, with a third under investigation. Mosquito spraying begins tonight.

West Nile virus is the leading cause of mosquito-borne disease in the continental U.S. Most people who are infected with the virus are asymptomatic, but others can develop fever, and about 1 in 150 people who are infected develop a serious and sometimes fatal illness.

West Nile virus cases are on the rise across the country as mosquito season begins, according to public health officials. The Arkansas Department of Health is currently reporting fewer than five cases of the virus.

Due to the spread of tiger mosquitoes, France is now reporting rising numbers of cases of what were previously considered to be 'tropical' diseases such as chikungunya, Zika, dengue fever and West Nile virus.

To prevent West Nile, health experts recommend using insect repellent and avoiding going outdoors during dusk and dawn, as mosquitoes are the most active during those times.

An American crow from Walnut Creek is the second bird to test positive for West Nile virus, the Contra Costa Mosquito and Vector Control District said. Birds are the main reservoir for the virus, which is transmitted to humans and animals through the bite of an infected mosquito.