For four itchy and irritating months, police and fire dispatchers fought a flock of pesky fleas to a standoff inside Fairfax County's emergency communications nerve center.

The usual doses of insecticide by county exterminators didn't seem to work. So this week the county moved in once again for the kill, but the battle plan backfired.

Bringing up their big guns on Thursday night, authorities sprayed insecticide in the Emergency Operations Center. The effect on the bloodsucking parasites has not been fully assessed. The effect on many of the personnel who dispatch police officers and firefighters, however, was all too obvious.

Complaining of headache, nausea and light-headedness, they were forced to flee the center and take up temporary positions outside.

"It's nothing but plain stupidity for something like this to happen. . . ," said one dispatcher. "This is ridiculous."

The outcome was "completely unexpected," said Larry Spaine, director of the county's department of facilities management, who led the raid on the fleas.

"We wanted to give it a good going over," he explained, adding that this was the first time such a problem had occurred during an extermination.

No one was hospitalized and officials said they do not believe any serious illnesses will result.

The center's services, which involve taking the county's 911 calls and dispatching police, firefighters and ambulance personnel, were not disrupted, police spokesman Warren Carmichael said.

But the center's operations did proceed on a kind of emergency footing. The actual dispatching was carried on in two mobile communications units parked behind the center's offices in the county's Massey Building at 4100 Chain Bridge Rd.

A special telephone line linked operators taking 911 calls to dispatchers outside.

Employes began complaining about 10 p.m. Thursday, shortly after the petroleum-based insecticide was sprayed in the EOC. Spaine said the spray was trained on the dispatch center's rug, which was thought to be the fleas' stronghold.

By midnight Thursday authorities began rotating the dispatchers' assignments. After 30 minutes of taking 911 calls inside the dispatch center, employes were scrutinized by medics for 30 minutes. Then they were sent outside for 30 minutes' duty in the mobile units.

By 3 p.m. yesterday, operations were back to normal.

After the smoke and spray of battle had cleared, Dave Petersen, operations chief for facilities management, was asked whether sufficient firepower had been used to wipe out the fleas.

"I hope so," he said.