An outbreak of irritating insect bites among federal employees in Clarksville, Tennessee last year turned out to be due to a bedbug infestation in the building where they worked, according to a U.S. Centers for Disease Control and Prevention report.

At least 35 workers suffered bedbug bites. Although the bites don't carry disease or cause serious health problems, they do cause welts, itching and swelling. Investigators found that one woman had bite bugs all over her body.

The infestation was confirmed by a bedbug-detecting German Sheherd.

Bedbug infestations have skyrocketed in the U.S. since 2000, affecting large urban areas and small towns, luxury hotels, apparel stores and yes, workplaces.

A 2011 survey of U.S. pest control companies found that 38 percent had responded to infestations at office buildings, up from 17 percent the year before. Treatments at schools and day-care centers rose to 36 percent from 10 percent, and visits to hospitals jumped from 12 percent of their jobs to almost one-third.

This data contradicts the previous perception of bedbugs as biting people only at night, only in beds.

In the Tennessee outbreak, employees began reporting bites and itching last June, leading state health department inspectors to investigate. They considered -- then excluded -- the possibility that the bites were being caused by scabies and fleas. The canine bedbug expert was able to nail down the actual cause in September. He detected the insects in a number of cubicles and offices in the building,

His diagnosis was confirmed by dermatologists.

CDC epidemic intelligence officer Dr. Jane Baumblatt said more than half of the employees interviewed suffered from bites, often on their legs. "It wasn't that severe. It was more of a nuisance than anything," Baumblatt said. "The anxiety was that people didn't know what it was," she said. "Once people figured out they were bedbugs, they were relieved."

A pest control company was hired to perform perform steam cleaning of theoffice.

Dr. Michael Potter, professor ofentomology at the University of Kentucky, said bedbugs do prefer beds and stationary furniture such as couches and recliners because they don't like disruption when they feed on people. But they may be transported to offices, day-care centers or myriad other locations in personal belongings such as backpacks, briefcases and purses.

Once an office becomes infested, managers may not want to tell workers in order to avoid a panic, he said. "In the best of all worlds, the office would inform the employees that some bedbugs have been spotted and they have a pest control company that's hopefully involved in dealing with things," he said.

However, Potter added, "nothing is easy when it comes to bedbugs."