Viral Hepatitis B, 2007

In 2007, 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, six 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 1,022 reports of newly identified cases of chronic HBV infection.

Acute cases ranged in age from 23 to 79 years (median, 47 years). Twelve (48%) of the 25 cases were residents of the metropolitan area, including five (20%) in Hennepin County and two (8%) in Ramsey County. Fourteen (56%) cases were male and 10 (40%) were adolescents or young adults between 13 and 39 years of age. Ten (40%) were white, two (8%) were black, and one (4%) was Asian; race was unknown for 12 (48%) cases. Two (8%) case-patients were of Hispanic ethnicity. Although the majority of cases were white, incidence rates were higher among blacks (0.9 per 100,000), Hispanics (0.9 per 100,000), and Asians (0.5 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. Five (20%) case-patients reported illicit drug use. Of these, two (40%) case-patients reported injection drug use. Ten (40%) case-patients reported having sexual contact with one or more partners within 6 months prior to onset of symptoms. Of these, three (30%) case-patients reported sexual contact with two or more partners, three (30%) case-patients were males who reported having at least one male sexual partner, and one (10%) case-patient reported having sexual contact with a known carrier of hepatitis B surface antigen (HBsAg). Two (8%) of the 25 total case-patients reported having household contact with a known carrier of hepatitis B (HBsAg). No risk factor was identified for eight (32%) cases.

In addition to the 25 hepatitis B cases, one perinatal infection was identified in an infant who tested positive for HBsAg during post-vaccination screening performed between 9 and 15 months of age. The perinatal case-patient was born in 2006. The perinatal infection occurred in an infant identified through a public health program that works to ensure appropriate prophylactic treatment of infants born to HBV-infected mothers. The infant was 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 (i.e., was a treatment failure). Despite this treatment failure, the success of the public health prevention program is demonstrated by the fact that an additional 325 infants born to HBV-infected women during 2006 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, 2007