The U.S. Department of Health and Human Services said 37 cases have been reported.
The department said those who tested positive before their arrival in the U.S. came in on a separate plane and were being isolated on a separate floor at the convention center.
Approximately 500 girls between 13 and 17 years old were brought to the 616,000-square-foot facility over the weekend.
Meanwhile, the Biden administration is not requiring FBI fingerprint background checks of caregivers at its rapidly expanding network of emergency sites to hold thousands of immigrant teenagers, alarming child welfare experts who say the waiver compromises safety.
Biden staffer blocks Ted Cruz from recording video at migrant facility in Texas
In the rush to get children out of overcrowded and often unsuitable Border Patrol sites, President Joe Biden's team is turning to a measure used by previous administrations: tent camps, convention centers and other huge facilities operated by private contractors and funded by U.S. Health and Human Services. In March alone, the Biden administration announced it will open eight new emergency sites across the Southwest adding 15,000 new beds, more than doubling the size of its existing system.
These emergency sites don't have to be licensed by state authorities or provide the same services as permanent HHS facilities. They also cost far more, an estimated $775 per child per day.
The Associated Press contributed to this report.