Viral Hepatitis B, 2006

In 2006, 32 cases of clinically symptomatic acute hepatitis B virus (HBV) infection (0.6 per 100,000) were reported, with no deaths. In addition to the 32 cases, seven 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 received 1,136 reports of newly identified cases of chronic HBV infection.

Acute cases ranged in age from 12 to 71 years (median, 37 years). Twenty-three (72%) of the 32 cases were residents of the metropolitan area, including 16 (50%) in Hennepin County and three (9%) in Ramsey County. Twenty (63%) cases were male, and 17 (53%) were adolescents or young adults between 13 and 39 years of age. Seventeen (53%) were white, six (19%) were black, and three (9%) were American Indian; race was unknown for six (19%) cases. Two (6%) case-patients were of Hispanic ethnicity. Although the majority of cases were white, incidence rates were higher among American Indians (5.3 per 100,000), blacks (2.7 per 100,000), and Hispanics (1.0 per 100,000) than among non-Hispanic whites (0.4 per 100,000).

Twelve (38%) of the 32 case-patients were interviewed regarding possible modes of transmission. A case-patient may report more than one risk factor. Of the 12 case-patients interviewed, 10 (83%) reported having sexual contact with one or more partners within 6 months prior to onset of symptoms. Two of the 10 case-patients reporting sexual activity reported having sexual contact with a known carrier of hepatitis B surface antigen (HBsAg). Three of the 10 case-patients reporting sexual activity reported sexual contact with two or more partners. Of seven males reporting sexual activity, four (57%) males reported only female partners, and three (43%) reported only male partners. All three of the females reporting sexual activity reported only male partners. One (8%) of the 12 case-patients interviewed reported being incarcerated for more than 24 hours. Two (17%) case-patients reported no risk factors.

Hepatitis B vaccine has been available since 1982, yet it continues to be underutilized in persons at greatest risk of infection. A large proportion of hepatitis B case-patients identified risk factors for sexual transmission; therefore, health care providers should discuss the need for HBV testing and vaccination with at-risk patients, including all unvaccinated adolescents, young adults, and patients seen for other sexually transmitted diseases. It is also recommended that all adults wishing to obtain immunity be vaccinated without requiring them to acknowledge a specific risk factor (CDC. A comprehensive immunization strategy to eliminate transmission of hepatitis B virus infection in the United States:Recommendations of the Advisory Committee on Immunization Practices [ACIP] Part II: Immunization of adults. MMWR 2006;55[No. RR-16]:1-25).

In addition to the 32 hepatitis B cases, six perinatal infections were identified in infants who tested positive for HBsAg during post-vaccination screening performed between 9 and 15 months of age. One perinatal case-patient was born in 2004 and five were born in 2005. All six 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. The 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 (i.e., were treatment failures). Despite these treatment failures, the success of the public health prevention program is demonstrated by the fact that an additional 430 infants born to HBV-infected women during 2005 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, 2006