COSTA MESA

They infiltrated City Hall two weeks ago and began taking out scores of city workers. The bugs--most commonly appearing in the form of the stomach flu, bronchitis and the ubiquitous cold--hobbled more than a quarter of the city’s 660 employees last month, according to the city’s personnel department. Sick employees missed an average of 2 1/3 workdays because of their illnesses in January. City Manager Allan L. Roeder was knocked out of his frenetic routine with bronchitis for a few days in late January. He tried coming back to work earlier this week but had a relapse. Roeder’s assistant, Chris Herendeen, caught the bug and called in sick Tuesday. And Deputy Dist. Atty. Donald Lamm was out all week with the stomach flu. The Building and Safety Department was hit pretty hard, said Cheryl Hansen, a receptionist for the Planning Department down the hall. She didn’t know how many people from the department were out sick Tuesday. And the two supervisors from the department who would normally know were home sick themselves.