A West Nile virus outbreak in Dallas County on Wednesday forced Mayor Mike Rawlings to declare a state of emergency.
"The number of cases, the number of deaths are remarkable, and we need to sit up and take notice," Rawlings said. "We do have a serious problem right now."
Bloomberg Bussinessweek reports Dallas and other North Texas cities will implement aerial spraying of insecticides to combat the mosquito-borne illness that has now killed 16 people. About 336 cases have been reported, according to the Center for Disease Control.
Dr. Lon Kightlinger, a disease specialist in South Dakota, told CBS News "the actual number of West Nile cases is probably much higher, because most people don't know they have the virus."
The last time Dallas used aerial spraying was in 1966.
Slate says it’s not clear why the virus is spreading now. However, some experts say warm weather may be one of many contributing factors.
“The [West Nile] pathogen — the warmer the temperature, the faster it moves from the blood to being transmitted," Marm Kilpatrick, an assistant professor in ecology and evolutionary biology at the University of California, Santa Cruz, told gristmill. It usually takes a while for the virus to get into the mosquito’s salivary glands. The biting rate also gets faster. So those things are all going to give you more transmission.”
After residents voiced concern about insecticides sprayed over their homes, State Health Commissioner Dr. David Lakey said, "The risk of air-based spraying is minimal versus the ongoing spread of West Nile."