HOUSTON -- A Houston doctor said we probably don't have an accurate picture of how widespread swine flu is, KPRC Local 2 reported Monday.

Dr. Ed Uthman is a pathologist who tests flu samples.

"The question immediately comes up, could this be H1N1?" said Uthman.

For that testing, the specimens are sent to the City of Houston Health Lab.

Uthman said he's been waiting and waiting for answers.

"It's been more than 10 days and still no results," said Uthman.

The Houston Health Department said it has received more than 6,300 samples from 17 counties. Of those, about 2,300 were tested. Fifty-two came back from the Centers for Disease Control and Prevention positive for swine flu.

By our calculations, about 4,000 specimens are still sitting there waiting to be tested.That's quite a backlog -- enough for the health department to add a third shift of lab workers starting Tuesday to get through them all.

"Yes, there is a backlog, but we have prioritized people with symptoms," Houston Health Department spokeswoman Kathy Barton said. "People with no symptoms are tested much later."

Working around the clock, Barton said they should catch up in a few weeks.

"We have always said to doctors, if patients come in with symptoms, treat them for influenza," said Barton. "Don't wait on tests."

Uthman said we can't get an accurate picture of how widespread the problem is until the tests are done.

"The only way we know a case is confirmed, is if they're tested," said Uthman.

The health department also now has the ability to confirm swine flu cases without sending them to the CDC for further testing.