SAN ANTONIO, Texas -

Hand-held mosquito fogging will begin at Ft. Sam Houston after further sample pools came back positive for West Nile Virus.

Bexar County officials are increasing their efforts to control the mosquito population.

Officials at Joint Base San Antonio announced plans to treat areas at Fort Sam Houston with hand-held mosquito foggers after 13 more sample pools came back positive for West Nile Virus, adding to the three original positive tests the week of July 18.

"We've been laying down the larvicide, the bacteria that kills the larva, and now we're going after the adult mosquitoes with this fogging," said JBSA spokesman Brent Boller, adding that hand-held foggers are more directed and specific than aerial spraying.

The fogging is planned for Thursday and Friday between midnight and 3 a.m. and will focus on areas near the post golf course and the honor guard horse stables, where the first three positive samples were found.

"We're not alarmed but we are taking this very seriously because it's an issue," said Boller. "Certainly we've heard about the issue in north Texas and we don't have that nearly to that degree here in San Antonio area or in JBSA Fort Sam Houston, but we're taking every precaution possible."

This summer MetroHealth has seen only two confirmed cases of the virus in its jurisdiction. But its working closely with Bexar County Public Works to avoid an outbreak.

"We're going to begin to trap the mosquitoes so that we can get them tested and work with the health department," said Public Works director Renee Green.

The county is in the third round of spraying the 1,188 miles of roadways and 4,200 acres of ditches and drains in its jurisdiction to treat both adult mosquitoes and larva. The county has upgraded the larvicide bricks it set in waterways, using bricks that last up to 90 days instead of the previous version, which would last 30.

"We've decided to go ahead and ramp up the activities," said Green. "We're going to treat the county parks as well, treat them as needed."

Emergency Manager Kyle Coleman also informed Commissioners Court today about the creation of a task force of several departments that will meet to devise a new response and outreach plan in case more cases of West Nile Virus appear in Bexar County.