Hepatitis C prevalence among Australian injecting drug users in the 1970s and profiles of virus genotypes in the 1970s and 1990s.

OBJECTIVES: To examine the seroprevalence of hepatitis C virus (HCV) in the Australian injecting drug-using community in the 1970s, and to compare the profile of HCV genotypes with that seen in the 1990s. DESIGN: Investigation of stored sera that were collected from injecting drug users in the 1970s and comparison with sera collected in the 1990s. SETTING: Inner Sydney, 1974-1975 and 1994-1996. PATIENTS: The 1970s group comprised 141 consecutive injecting drug users who attended the Brisbane Street Methadone Clinic. The 1990s group comprised 88 consecutive, injecting drug users of European origin who were HCV antibody-positive and attended a primary healthcare facility (the Kirketon Road Centre). MAIN OUTCOME MEASURES: HCV antibody prevalence (1970s); profile of HCV serotypes (1970s and 1990s); and serological evidence of hepatitis A and B. RESULTS: 84% of the 1970s group were HCV antibody-positive, of whom 92% were infected with HCV serotype 1 and 1% with serotype 3. In contrast, in the 1990s group, 69% were infected with HCV serotype 1 and 25% with serotype 3. The HCV-positive subjects from the early group were more likely than those from the recent group to have serological evidence of previous HBV infection. CONCLUSIONS: The high prevalence of HCV among injecting drug users in the 1970s in Australia confirms an epidemic that has been present for at least 25 years. Over this period, the proportion of HCV genotype 1 infections has decreased and genotype 3 infections have emerged.

A serological re-evaluation of acute non-A non-B hepatitis from the early 1970s.

BACKGROUND: The epidemiology and natural history of recently discovered viruses, which may be responsible for cases of seronegative infectious hepatitis, are currently being investigated. Retrospective studies of stored sera can provide a historical perspective of these infections. AIMS: To re-evaluate the serological, demographic and clinical characteristics of patients hospitalised in the early 1970s with acute hepatitis. METHODS: The stored sera of 57 patients hospitalised between 1971 and 1974 with acute hepatitis, designated at that time as non-A non-B (NANB) hepatitis, were re-tested using commercially available enzyme-linked immunosorbent assays (ELISAs) for the presence of anti-hepatitis A virus (HAV) IgM, hepatitis B surface antigen (HBsAg), anti-hepatitis C virus (HCV) IgG, and anti-hepatitis E virus (HEV) IgG. Stored sera from a group of 57 patients concurrently hospitalised for other conditions were also tested. Detailed records of the original epidemiological interviews were examined to compare patient demographics, risk factors for infectious hepatitis and clinical data for the NANB hepatitis group and an original control group of 604 hospitalised patients. RESULTS: Serum from 15 of the 57 (26%) previously designated NANB hepatitis cases had elevated anti-HAV IgM and are likely to represent missed cases of hepatitis A. Thirteen (23%) of cases previously designated as NANB hepatitis had positive hepatitis C antibody tests. These patients were younger and significantly more likely to have used intravenous drugs than control patients. Three NANB hepatitis and two hospital control patients were anti-HEV IgG antibody positive. All of these individuals were born in, or had travelled to, developing countries. Serum from 27 (47%) of the NANB hepatitis patients were negative on all tests. These hepatitis non-A-E cases included children and elderly adults, but as a group were significantly more likely to have used intravenous drugs than hospitalised control patients. CONCLUSION: Both HCV and probable non-A-E virus(es) were important causes of acute NANB hepatitis during the early 1970s.

Pertussis vaccines: acellular versus whole-cell.

Acellular pertussis vaccines containing purified Bordetella pertussis antigens have now been extensively field tested. They produce a significantly lower rate of reactions than whole-cell vaccines and their efficacy is either comparable or superior. At least three antigens appear necessary for good protection: pertussis toxoid, filamentous haemagglutinin and pertactin (an outer-membrane protein); fimbrial agglutinogens are probably not needed. It is hoped that a cellular pertussis vaccine will soon be licensed in Australia for both primary and booster vaccination.

Arbovirus infections of humans in high-risk areas of south-eastern Australia: a continuing study.

OBJECTIVES: To determine the current immune status of high-risk populations of New South Wales and Victoria to the arboviral pathogens, Murray Valley encephalitis (MVE) and Kunjin (KUN) viruses, which are associated with Australian encephalitis (AE), and Ross River (RR) and Kokobera (KOK) viruses which are associated with polyarthritis. Further, to estimate seroconversion rates to these viruses in high-risk populations over the 10-year period 1981-1991. DESIGN AND STUDY POPULATION: Blood was taken from 2873 permanent residents, children and adults from previously identified high-risk areas in western NSW and northern Victoria. Samples were tested by the haemagglutination-inhibition (HI) test for antibodies to the four viruses. All sera were also tested for MVE and KUN antibodies by the more specific neutralisation test (NT). Ninety-five of the subjects had been seronegative when sampled 10 years previously. RESULTS: Age standardised prevalence rates for flavivirus HI antibodies (MVE, KUN, KOK) ranged from 66% (Bourke) to 15% (Forbes), and were similar to those observed 10 years previously. However, specific NT antibodies to MVE and KUN were uncommon in all districts except Bourke, indicating a very high level of susceptibility to Australian encephalitis, should a fresh epidemic occur. Whereas KUN virus seems enzootic in NSW and Victoria, MVE did not appear to have been present since the last outbreak in 1974, even in Bourke. Flavivirus antibody rates (as detected by the broadly reactive HI test) greatly exceeded those specifically attributable to MVE and KUN (NT test) or KOK, leading to the speculation that unidentified flaviviruses are responsible for most human infections. Ross River virus antibody prevalence rates exceeded those of flaviviruses in all districts, ranging from 72% (Bourke) to 25% (Cohuna), and were uniformly higher than those observed in 1981. Ten-year seroconversion rates in seronegative panels were 8.5% for flaviviruses and 24.2% for RR virus, and are broadly consistent with the cross-sectional study. CONCLUSIONS: Although flavivirus and alphavirus infections have occurred at a "steady rate"in western NSW and northern Victoria, there is a general lack of immunity to the agents of Australian encephalitis in all centres except Bourke. This needs to be considered in public health policy in these areas.

Prevalence of chronic fatigue syndrome in an Australian population.

An epidemiological study was undertaken to provide the first reported estimate of the point prevalence of chronic fatigue syndrome in an Australian community. After a pilot study in a separate location, the population of the Richmond Valley, New South Wales, was sampled using a structured case-finding technique, which included notification from local medical practitioners, the use of a screening questionnaire and standardised interviews conducted by a physician and psychiatrist. In addition, investigations were performed to exclude alternative diagnoses and to assess cell-mediated immunity. Forty-two patients with chronic fatigue syndrome, with a female:male ratio of 1.3:1.0, were detected in a population of 114,000. The mean age at onset of symptoms was 28.6 years (SD, 12.3 years), and the median duration of symptoms from onset to sampling date was 30 months. The social status of the patients was distributed in accordance with that of the remainder of the population sampled, with no bias towards the middle or upper social classes. The disorder was causing considerable incapacity, with 43% of patients unable to attend school or work. The conservative estimate from this study suggests a prevalence on June 30 1988 of 37.1 cases per 100,000 (95% confidence interval [CI], 26.8-50.2). Chronic fatigue syndrome is an important disorder in this Australian community that affects young individuals from all social classes and causes considerable ill health and disability.

Defined epitope blocking with Murray Valley encephalitis virus and monoclonal antibodies: laboratory and field studies.

In an attempt to develop a specific serological test for Murray Valley encephalitis (MVE) virus antibodies, a panel of MVE monoclonal antibodies was utilised in defined-epitope blocking ELISA tests. In sera of mice immunised singly and in combinations of MVE, Alfuy (ALF), and Kunjin (KUN) viruses, blocking patterns usually distinguished MVE infections from those of the other flaviviruses. When blocking tests with selected MAbs were applied to 468 flavivirus antibody positive sera collected from human subjects throughout New South Wales, sera with blocking patterns consistent with previous MVE infection were found in 18 subjects. All were long-term residents of areas previously frequented by MVE, and all were of an age to have been exposed to the virus in past epidemics. No such sera were found in subjects living in coastal areas of NSW where MVE has never been reported.

Arbovirus infection in humans in NSW: seroprevalence and pathogenicity of certain Australian bunyaviruses.

A sero epidemiological study was carried out on human sera from all regions of New South Wales for the presence of antibodies to nine bunyaviruses viz Aino, Akabane, Belmont, Gan Gan, Kowanyama, mapputta, Peaton, Tinaroo, Trubanaman and the orbivirus Corriparta. Neutralising antibodies were found in titres up to 1280 to Gan Gan and to 640 to Trubanaman viruses, prevalences 4.7% and 1.4% respectively. Neutralisation titres up to 40 were found to Belmont, Aino, Peaton and Corriparta viruses but the significance of these is uncertain since they may represent either non-specific inhibitors or cross reacting antibodies to related but currently unknown viruses. No antibodies were found to Akabane, Kowanyama, Mapputta or Tinaroo viruses in New South Wales sera. Gan Gan virus appeared to be pathogenic for man being associated with an acute epidemic polyarthritic like illness. Trubanaman virus is suspected of being pathogenic. This is the first report of the pathogenicity of these Australian bunyaviruses.

Immunological abnormalities in the chronic fatigue syndrome.

The chronic fatigue syndrome is a disorder of unknown aetiology which is characterized by debilitating fatigue. Recent evidence has suggested that viruses may persist in the tissues of patients with chronic fatigue syndrome. A concurrent immunological disturbance is likely to be associated with the persistence of viral antigens. Therefore, the humoral and cellular immunity of 100 patients who were suffering from chronic fatigue syndrome and that of 100 healthy, age- and sex-matched control subjects were compared. This study documents the frequent occurrence of abnormalities within the cellular and humoral immune systems of patients with well-defined chronic fatigue syndrome. Disordered immunity may be central to the pathogenesis of chronic fatigue syndrome. In patients with chronic fatigue syndrome, a significant (P less than 0.01) reduction was found in the absolute number of peripheral blood lymphocytes in the total T-cell (CD2), the helper/inducer T-cell (CD4) and the suppressor/cytotoxic T-cell (CD8) subsets. A significant (P less than 0.001) reduction also was found in T-cell function, which was measured: in vivo by delayed-type hypersensitivity skin-testing (reduced responses were recorded in 50 [88%] of 57 patients); and in vitro by phytohaemagglutinin stimulation. Reduced immunoglobulin (Ig) levels were common (56% of patients), with the levels of serum IgG3- and IgG1-subclasses particularly (P less than 0.05) affected.

Illness caused by a Barmah Forest-like virus in New South Wales.

Barmah Forest virus, a recently-discovered arbovirus which belongs to the alphavirus genus of the family Togaviridae, has been shown to cause infections in humans in New South Wales. The present report documents three patients in whom Barmah Forest viral infection appears to have resulted in illness. Barmah Forest virus or a closely-related alphavirus may, as are several other alphaviruses, be pathogenic.

Barmah Forest virus infections in humans in New South Wales.

Antibodies to Barmah Forest virus, a member of the alphavirus group, which was first isolated in 1974, have been found to be widespread in humans in New South Wales. Antibody studies showed a higher prevalence in the north coastal zones of the State, and lower rates in individuals who were living in all other biophysical zones. Antibody rates were significantly higher in male than in female subjects. The pathogenicity of the Barmah Forest virus is at present not known.