Mosquitoes with the West Nile virus have been detected at all Joint Base San Antonio locations.
On Thursday, three mosquito pool samples tested positive at Camp Bullis. Three sample pools at JBSA-Lackland and one at JBSA-Randolph tested positive on Friday.
A second round of mosquito fogging was administered at JBSA-Fort Sam Houston Friday where several mosquito samples have tested positive for West Nile.
JBSA officials said all precautions are being taken to protect trainees and residents.
"We take no chances," JBSA spokesman Brent Boller said. "We do everything we can to protect the trainees, and those other than trainees, those who are permanent residents and workers of Joint Base San Antonio."
Boller said JBSA officials are exploring treatment options.
"A lot of what we're doing is precautionary because safety is rule number one," he said.