Viral Hepatitis B, 2002
In 2002, 52 cases of acute hepatitis B virus (HBV) infection (1.1 per 100,000 population) were reported, including one death. Forty-five (87%) of these cases had clinical symptoms; the remaining seven had documented asymptomatic seroconversions. Thirtysix (69%) case-patients were residents of the seven-county Twin Cities metropolitan area, including 17 (33%) in Hennepin County. Thirty-one (60%) case-patients were male, and 39 (75%) were adolescents or young adults between 16 and 39 years of age. Twenty-six (50%) case-patients were white, 16 (31%) were black, three (6%) were American Indian, and three (6%) were Asian; race was unknown for four (8%) cases (all were of Hispanic ethnicity). Although the majority of cases were white, incidence rates were higher among blacks (9.3 per 100,000), American Indians (5.5 per 100,000), Hispanics (2.8 per 100,000), and Asians (2.1 per 100,000) than among whites (0.6 per 100,000).
In addition to the 52 reported cases, six perinatal infections were identified in infants who tested positive for hepatitis B surface antigen (HBsAg) during post-vaccination screening. Three of the infants were born in 2000, and three were born in 2001. Four of these six infants were age-appropriately vaccinated with hepatitis B immune globulin (HBIG) and three doses of HBV vaccine. Two infants were delayed in the receipt of the third dose of vaccine.
Forty-four (85%) of the 52 cases were interviewed regarding possible modes of transmission. For 19 (43%) of those cases, the likely mode of transmission was sexual. Ten (23%) case-patients reported heterosexual contact with a known carrier of HBsAg, six (14%) reported heterosexual contact with multiple partners within 6 months prior to onset of symptoms, and three (7%) were men who reported having sex with men. One (2%) case-patient used needles to inject drugs and reported sexual contact with a known carrier of HBsAg. Three (7%) case-patients reported having had surgery within 6 months prior to onset of symptoms. Two (5%) cases involved non-sexual contact with HBsAg-infected persons. No cases were reported as a result of occupational exposure. Risk factors for acquiring HBV infection were not identified for the remaining 19 (43%) cases. These 19 cases and the eight who were unavailable for interviews were between 20 and 80 years of age (median, 34 years).
The Minnesota School Immunization Law requires HBV vaccination of students, unless they are legally exempt. HBV infections continue to occur in high-risk adolescents and adults who were beyond seventh grade when this law came into effect during the 2001-2002 school year. The majority of cases reported in 2002 with an identified risk factor indicated likely sexual transmission; therefore, health care providers should discuss the need for HBV testing and vaccination with at-risk patients, including patients seen for other sexually transmitted diseases.