Viral Hepatitis B, 2009

In 2009, 39 cases of symptomatic acute hepatitis B virus (HBV) infection (0.7 per 100,000 population) were reported, with no deaths. In addition to the 39 cases, four individuals with documented asymptomatic seroconversions were reported. Prior to 2006, both symptomatic cases and asymptomatic seroconvertors were counted as incident cases. This change in case counting criteria should be considered when examining case incidence trends.

MDH also received 567 reports of newly identified cases of confirmed chronic HBV infection in 2009. Prior to 2009, confirmed and probable chronic cases were reported in the year in which they were first reported. Beginning in 2009, only confirmed cases are reported, and cases are reported in the year in which case confirming data are available. A total of 18,519 persons are assumed to be alive and living in Minnesota with chronic HBV. The median age of chronic HBV cases in Minnesota is 41.

Acute cases ranged in age from 14 to 77 years (median, 40 years). Twenty-nine (74%) of the 39 cases were residents of the metropolitan area, including 11 (28%) in Hennepin County and 12 (31%) in Ramsey County. Thirty (77%) cases were male and 18 (46%) were adolescents or young adults between 13 and 39 years of age. Fifteen (38%) were white, 5 (13%) were black, 4 (10%) were Asian, and 1 (3%) was of other race; race was unknown for 14 (36%) cases. One case was known to be of Hispanic ethnicity (0.5 per 100,000). Although the majority of cases were white, incidence rates were higher among blacks (2.0 per 100,000) and Asian Pacific Islanders (2.0 per 100,000) than among non-Hispanic whites (0.3 per 100,000).

MDH attempts to ascertain risk factor information and possible modes of transmission by collecting information reported by the case to his/her health care provider and by interviewing the case directly, if possible. A case may report more than one risk factor. Seven (18%) cases reported having sexual contact with one or more partners within 6 months prior to onset of symptoms. Of these, 3 (43%) reported sexual contact with two or more partners, 3 (43%) were males who reported having one or more male sexual partners, 1 (14%) was a male who reported sexual contact with one female partner, and 3 (43%) cases were females who reported one or more male sexual partners. One (3%) case reported having sexual contact with a known carrier of hepatitis B surface antigen (HBsAg). No risk factor was identified for 28 (72%) cases.

In addition to the 39 hepatitis B cases, 4 perinatal infections were identified in infants who tested positive for HBsAg during post-vaccination screening performed between 9 and 15 months of age. The infants were born in 2008. The perinatal infections were identified through a public health program that works to ensure appropriate prophylactic treatment of infants born to HBV-infected mothers. All four infants were born in the United States and had received hepatitis B immune globulin and 3 doses of hepatitis B vaccine in accordance with the recommended schedule and were therefore considered treatment failures. Despite these treatment failures, the success of the public health prevention program is demonstrated by the fact that an additional 321 infants born to HBV-infected women during 2008 had post-serologic testing demonstrating no infection.

• For up to date information see>> Hepatitis B
• Full issue>> Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2009