Metro-area health officials are hunting down mosquitoes this summer to prevent the spread of West Nile virus.
The Oklahoma City-County Health Department initiated a new mosquito trapping and surveillance program in response to last year's record-breaking West Nile numbers, state Epidemiologist Kristy Bradley said.
In 2012, 15 Oklahomans died from the disease, and 144 were hospitalized.
West Nile virus arrived in Oklahoma in 2002 and has taken 36 lives since. The numbers have been as low as no deaths reported in 2008 and as high as 15 deaths in 2012.
Bradley said it's impossible to determine why some years are worse than others, but outbreaks seem to occur once every three to four years. Although scientists can't predict when an outbreak will occur, they can take steps to help prevent one from happening.
During the past year, officials brainstormed ideas for avoiding another outbreak. A mosquito trapping and testing program that started in May could prove to be the most effective technique to combat the virus, environmental field supervisor Troy Skow said.
West Nile is spread to humans primarily through bites from mosquitoes that acquire the virus from infected birds. By placing 10 traps outside fire stations throughout Oklahoma City and Edmond, technicians are capturing mosquitoes that could carry the virus.
The traps are filled with carbon monoxide, which attracts mosquitoes trying to lay their eggs, Skow said. As mosquitoes approach the device, they are sucked into a netted compartment, where they remain unharmed until retrieval.
“It's kind of a mosquito soup that traps the mosquito in,” he said.
The preserved mosquitoes are collected weekly and brought to a Health Department laboratory to test for West Nile, said Phil Maytubby, chief of public health protection.
Technicians separate harmless mosquitoes from culex mosquitoes — a genus of mosquito that is the primary carrier of West Nile. Only females bite and spread diseases, so males are removed from the testing group. If a positive result is found, health officials determine what steps need to be taken to keep the virus from spreading.
“We try to eliminate mosquitoes and larvae where the infected mosquito was found by reducing habitats in the area,” Maytubby said.
Culex mosquitoes breed in standing, stagnant water, such as in unused swimming pools or in clogged drain pipes, Bradley said. When an infected mosquito is identified, an extermination team goes to the area where it was trapped and applies a chemical larvicide to possible breeding grounds. If the larvicide isn't applied in time and the larvae mature, another chemical is used to kill free-flying adult mosquitoes.