Viral Hepatitis B, 2008

In 2008, 25 cases of symptomatic acute hepatitis B virus (HBV) infection (0.5 per 100,000 population) were reported, with no deaths. In addition to the 25 cases, two 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 911 reports of newly identified cases of chronic HBV infection in 2008.

Acute cases ranged in age from 12 to 79 years (median, 43 years). Sixteen (64%) of the 25 cases were residents of the metropolitan area, including eight (32%) in Hennepin County and three (12%) in Ramsey County. Nineteen (76%) cases were male and 10 (40%) were adolescents or young adults between 13 and 39 years of age. Ten (40%) were white, nine (36%) were black, and three (12%) were Asian or Pacific Islander; race was unknown for three (12%) cases. No case-patients were known to be of Hispanic ethnicity. Although the majority of cases were white, incidence rates were higher among blacks (3.6 per 100,000) and Asians and Pacific Islanders (1.6 per 100,000) than among non-Hispanic whites (0.2 per 100,000).

MDH attempts to ascertain risk factor information and possible modes of transmission by collecting information reported by the case-patient to his/her health care provider and by interviewing the case-patient directly, if possible. A case-patient may report more than one risk factor, and may report different information to his/her health care provider than to MDH. Four (16%) case-patients reported illicit drug use. Of these, one (25%) reported injection drug use. Seven (28%) case-patients reported having sexual contact with one or more partners within 6 months prior to onset of symptoms. Of these, one (14%) reported sexual contact with two or more partners, one (14%) was a male who reported having one male sexual partner, two (29%) were males who reported sexual contact with one female partner, one (14%) case-patient was a male who reported having one sexual partner but did not report gender, and the remaining two (29%) case-patients reported sexual activity without identifying number or gender of partners. No case-patients reported having sexual contact with a known carrier of hepatitis B surface antigen (HBsAg). No risk factor was identified for 14 (67%) cases.

In addition to the 25 hepatitis B cases, 5 perinatal infections were identified in infants who tested positive for HBsAg during post-vaccination screening performed between 9 and 15 months of age. The perinatal case-patients were born in 2007. The perinatal infections occurred in infants identified through a public health program that works to ensure appropriate prophylactic treatment of infants born to HBV-infected mothers. All five infants were born in the United States and had received hepatitis B immune globulin and three doses of hepatitis B vaccine in accordance with the recommended schedule (ie, were treatment failures). Despite these treatment failures, the success of the public health prevention program is demonstrated by the fact that an additional 300 infants born to HBV-infected women during 2007 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, 2008