The Dallas County Health and Human Services Department said Tuesday it is concerned about the number of dangerous mosquitoes they're trapping this season.
None of the insects in last week's round of testing carried the potentially deadly West Nile virus, but the volume of mosquitoes presents a problem for health workers looking to focus their spraying efforts.
Zachary Thompson with the Dallas County Health and Human Services told county commissioners his inspectors are still working to identify where the mosquitoes are breeding.
The southern house mosquito is the specific kind of bug most likely to transmit the West Nile virus. In May, health workers trapped more than 17,000 of them.
In May of 2012, they found less than 1,000.
Thompson pointed out for commissioners that the health department is doing more testing and spraying than in years past.
"I want to be very clear. They're not positive for WNV, we're just looking at mosquito counts and we want to target them," Thompson said.
In 2012, 20 people died in Dallas County alone after contracting West Nile virus. Throughout North Texas last year, more than 1,000 human cases were confirmed and 40 people died.