No 47 - 2011

Acute and chronic hepatitis B 2010

Acute hepatitis B 2010

2010 saw 27 notifications of acute hepatitis B virus (HBV) infection, including 21 males, Table 1.

The median age was 40 years (range 20-81 years). Among the notified persons, 22 (81%) were Danish-born and five (19%) were immigrants.

A total of 18 (67%) were infected in Denmark; among these, 14 were Danish-born, while four were immigrants. Four cases (15%) were infected abroad, all Danish-born. In five cases, four Danes and a foreigner, the country of infection was not stated. Twelve of the 27 cases were infected by heterosexual contact, five by homosexual contact, and for ten persons the route of infection was unknown.

Chronic hepatitis B 2010

In 2010, a total of 136 cases of chronic HBV infection were notified, Table 2.
A total of 79 (58%) were women, Table 3, including 29 (37%) pregnant women. The median age was 33 years (range 1-65 years). Among the notified cases, 15 (13%) were of Danish origin and 121 (87%) of foreign origin. The immigrants were spread across 42 nationalities, and 55 (46%) were from Asia.

The most frequent route of infection was mother-to child transmission, Table 4.

One child with foreign parents was notified as HBV-infected in Denmark by birth. The child was born before the introduction of general HBV screening of pregnant women. A total of four cases were notified as nosocomially infected; one of these stated having been infected in Denmark. The person in question was presumably infected through blood products before the introduction of donor-blood screening.

General screening, pregnant women

In 2010, the general screening of pregnant women identified a total of 205 HBsAg positives, including sev-en (3%) of Danish origin, Table 5.

Only 105 of the 205 pregnant women (51%) were notified to the Department of Epidemiology on Form 1515 in accordance with physicians' obligation to notify infectious diseases.

Among the 105 pregnant women notified, 29 were notified in 2010 and four in 2011. Consequently, among all the notified cases, the share of newly notified was 31%. The remaining 72 had previously been diagnosed with chronic HBV infection and notified before the introduction of pregnancy screening.

Commentary

In 2010, the number of cases notified with acute HBV infection was in line with the low level observed in recent years. The number of persons notified with chronic HBV infection was lower than any other year since the infection became notifiable in 2000, Figure 1.

HBV infection acquired by birth is the primary cause of chronic HBV infection. In Denmark, children of immigrants from highly endemic areas have a higher risk of infection than all other groups.

Screening of pregnant women is therefore the primary task in the prevention of chronic HBV infection in Denmark.

A child born by a HBV carrier mother may be protected against transmission if vaccinated immediately after birth, and subsequently at 1, 2 and 12 months of age. It is essential that midwives and obstetricians check if the pregnant women's hepatitis B status is ticked in the pregnancy and hospital record, respectively. It is also important that GPs check if the patient has a positive HBsAg test result and that positive results are followed up in accordance with the National Board of Health guidelines on general screening of pregnant women, see www.sst.dk (Danish language).

(B. Søborg, S. Cowan, Department of  Epidemiology)

23 November 2011