Background Hepatitis C (HCV) is a public health threat of unknown magnitude. There is a huge potential future expenditure in terms of diagnostic, treatment, and transplant costs. It is likely that this will seriously impact both the private and public health care sectors. But it is difficult to make accurate estimates because so little is known about the characteristics of this disease in San Mateo County. It is known that HCV is the most prevalent blood-borne infection in the country. It is estimated that at least four times as many people are infected with HCV as with HIV in the US. Investigators also report that perhaps 15-40% of people with HIV, and as many as 90% of needle drug users with HIV, may be co-infected with HCV. Our best estimate is that 13,000 San Mateo County residents are infected. HCV screening tests are available to county residents free of charge for a limited time. Please call 573-2346 for details. Updated: 12/06/06