Heterosexual transmission may not be an important risk factor for hepatitis C (HCV) in the United States, according to a survey of health departments in five states conducted by the Centers for Disease Control and Prevention. Their findings were reported at the 50th Interscience Conference on Antimicrobial Agents and Chemotherapy in Boston. R. Monina Klevens, DDS, MPH, a medical epidemiologist with the Healthcare Outcomes Branch, was principal investigator. The researchers surveyed health departments in Colorado, Connecticut, Minnessota, Oregon, and New York, which themselves conducted surveillance of HCV infection from 2005 to 2009. The cases met clinical (acute illness with discrete onset of >/=1 sign or symptom of viral hepatitis and either jaundice or elevated serum alanine aminotransferase) and laboratory (a positive antibody to HCV with confirmation by RIBA, RNA, or high signal-to-cutoff ratio) criteria. Standard demographic and clinical data were collected for each case. The state investigators determined the presence of 21 potential HCV risk behaviors from two weeks to six months prior to symptom onset from a provider or the patient; cases could have one risk factor or more. According to Dr. Klevens, a total of 575 acute HCV cases were reported; 63 (11.0%) had no risk factors reported and were excluded. Of thse remaining, 247 (48.2%) reported using drugs, 202 (39.5%) reported heterosexual exposure, and 20 (3.9%) reported a same sex partner. Most heterosexual (126/202) and same sex partner cases (14/20) also used drugs. Drug use increased with the number of partners: 79.0% with >5 partners, 76.5% with 2-5 partners, 54.6% with 1 partner (P<0.01) used drugs. Forty-two out of 202 (20.8%) reported sexual contact with a person confirmed or suspected of HCV infection. Only 19/202 heterosexuals reported no other risks. Heterosexual cases with no other risks were not significantly different from those with >/=1 other risk by sex (P=0.07) and race (P=0.9) but were significantly older (43.2 vs 34.7 years, P<0.01). This study confirms prior research that suggests heterosexual transmission may not be an important risk factor for HCV in the US. However, the new CDC finding quantifies the extent to which increased age, increased number of sexual partners, and drug use are risks for HCV.