Inside the Genesee County Health Department, Mark Valacak gestures to a darkened office that until a few months ago housed a clinic providing free baby formula and diapers to poor mothers. Around a corner is another empty waiting area. It's Tuesday, one of the two days of the week the STD clinic is closed because of budget cuts, and Valacak worries that the service cutback could lead to an increase in syphilis and other sexually transmitted diseases. In cities and counties across the nation, the housing bust has hit health care. In Genesee County, where housing prices have plunged and foreclosures have been widespread, property tax revenues have declined by 15 percent over the past two years. The decrease is hampering efforts by the county, which is 75 miles northwest of Detroit and the birthplace of General Motors Corp., to provide healthcare to the poor as well as public health services.