Epidemiology of acute and chronic hepatitis B virus infection in Norway, 1992-2009

Abstract

BackgroundNorway is classified as a low prevalence country for hepatitis B virus infection. Vaccination is only recommended for risk groups (intravenous drug users (IDUs), Men who have Sex with Men (MSM), immigrants and contacts of known carriers). We describe the epidemiology of reported cases of hepatitis B in Norway, during the years 1992-2009 in order to assess the validity of current risk groups and recommend preventive measures.MethodsWe used case based data from the national surveillance system on acute and chronic hepatitis B. The Norwegian Statistics Bureau provided population and migration data and the Norwegian Institute for Alcohol and Drug Research the estimated number of active IDUs between 2002-2007. Incidence rates (IR) and incidence rate ratios (IRR) for acute hepatitis B and notification rates (NR) and notification rate ratios (NRR) for chronic hepatitis B with 95% confidence intervals were calculated.ResultsThe annual IR of acute hepatitis B ranged from 0.7/100,000 (1992) to 10.6/100,000 (1999). Transmission occurred mainly among IDUs (64%) or through sexual contact (24%). The risk of acquiring acute hepatitis B was highest in people aged 20-29 (IRR = 6.6 [3.3-13.3]), and in males (IRR = 2.4 [1.7-3.3]). We observed two peaks of newly reported chronic hepatitis B cases in 2003 and 2009 (NR = 17.6/100,000 and 17.4/100,000, respectively). Chronic hepatitis B was more likely to be diagnosed among immigrants than among Norwegians (NRR = 93 [71.9-120.6]), and among those 20-29 compared to those 50-59 (NRR = 5.2 [3.5-7.9]).ConclusionsIDUs remain the largest risk group for acute hepatitis B. The observed peaks of chronic hepatitis B are related to increased immigration from high endemic countries and screening and vaccination of these groups is important to prevent further spread of infection. Universal screening of pregnant women should be introduced. A universal vaccination strategy should be considered, given the high cost of reaching the target populations. We recommend evaluating the surveillance system for hepatitis B as well as the effectiveness of screening and vaccinating immigrant populations.

Hepatitis B prevalence in Denmark – an estimate based on nationwide registers and a national screening programme, as on 31 December 2007

“…Private practitioners participating in the study on pregnant women reported that 58% of cases had been known before the survey, and using this proportion, our national estimate would rise to 12,626 [8]. Correspondingly, an estimate from the United States (US) reported only 35% diagnosed HBV patients [22].…”

Detection of hepatitis B virus in the cerumen of patients with chronic hepatitis B infection

“…1 Two billion people have been exposed to HBV, 5 million cases of acute HBV infection occur annually and over 350 million people have a chronic infection. 2,3 Approximately 75 per cent of chronic carriers live in Asia and the Western Pacific region. 3 Hepatitis B virus is transmitted parenterally by contaminated blood or other body fluids through blood vessels, skin or mucous membranes.…”

Should Europe have a universal hepatitis B vaccination programme?

“…26 27 Therefore, family members, especially newborns of mothers from middle or high endemic countries, should be vaccinated, 24 as is done, for example, in Norway. 28 Screening of immigrants is not essential in preventing HBV transmission from immigrant children to other children, 22 23 29 but it does allow treatment of possible chronic infections. New antiviral drugs are effective and result in a sustained response in most patients, reducing the disease burden and also the risk of further transmission.…”