The prevalence, epidemiology and consequences of delta infection were analysed in 60 patients attending the Roslagstull Hospital for Infectious Diseases, Stockholm, Sweden, between 1972 and 1982. All of the patients had biopsy-documented chronic hepatitis B. Using radioimmunoassay techniques, sera from all patients were tested for antibodies to hepatitis A virus, for hepatitis B surface antigen and the corresponding antibody, for antibodies to hepatitis B core antigen, for hepatitis B e antigen and the corresponding antibody and for antibodies to delta antigen. All 60 patients underwent a liver biopsy which was repeated in 28 patients. 32% of the patients (19/60) were found to be anti-delta positive. The majority of the anti-delta positive patients were either immigrants from non-European countries or addicts (both 9/19 or 47%). Infections with delta agent were found to have already occurred in the Stockholm region in the early 1970s. During the study period, four of the patients developed clinical and laboratory signs of acute hepatitis in association with a delta infection. Among the anti-delta positive patients, 63% (12/19) were classified as having chronic active hepatitis, with or without cirrhosis, as against 39% (16/41) of the anti-delta negative patients. Histological progression to cirrhosis was observed in two of the four anti-delta positive patients with initial chronic active or chronic persistent hepatitis.
Three strains of nephropathia epidemica (NE) virus were isolated from lung tissues of bank voles (Clethrionomys glareolus) and a grey-sided vole (C. rufocanus) trapped in Västerbotten county, Sweden. Two of these isolates were serially passaged in seronegative laboratory-bred bank voles. Experimentally infected animals developed a subclinical infection characterized by virus persistence, particularly in lung tissue. Attempts to infect other species of colonized rodents with NE virus and to isolate NE virus from acute phase patient blood were unsuccessful. The serial propagation of NE virus in colonized bank voles provides opportunities to study experimental infection in its reservoir rodent host.
Sixty patients with liver biopsy documented chronic hepatitis B attending Roslagstull Hospital for Infectious Diseases, Stockholm, Sweden, were followed during a mean period of 53 months (range 7-133 months) in order to evaluate the frequency of delta infection and HBeAg seroconversion as well as the histological outcome as assessed by liver biopsy. Spontaneous HBeAg clearance and development of anti-HBe occurred among 17 of 36 initially HBeAg positive patients (47%), corresponding to an annual seroconversion rate of 11%. Biochemical improvement was noted in 7/17 patients (41%) after seroconversion as against in 2/19 patients (10.5%) with HBeAg persistence. Superinfection with the delta agent was seen to be associated with severe liver injury among drug addicts and immigrants with chronic hepatitis B. In the absence of a delta infection, progressive liver disease seemed to be associated with persistence of HBeAg. Although none of the homosexual men studied were delta superinfected, 71% developed chronic active hepatitis (CAH) with or without cirrhosis (CI).