Search

Ross River virus (RRV) is a mosquito-borne alphavirus indigenous to Australia and the Western Pacific region and is responsible for several thousand cases of human RRV disease (RRVD) per annum. The disease primarily involves polyarthritis/arthralgia, with many patients also presenting with rash, myalgia, fever, and/or lethargy. The symptoms can be debilitating at onset, but they usually resolve within 3-6 months. Recent insights into the RRV-host relationship, associated pathology, and molecular biology of infection have generated a number of potential avenues for improved treatment. Although vaccine development has been proposed, the small market size and potential for antibody-dependent enhancement (ADE) of disease make this approach unattractive. Recent insights into the molecular basis of RRV-ADE and the virus's ability to manipulate host inflammatory and immune responses create potential new opportunities for therapeutic invention. Such interventions should overcome virus-induced dysregulation of protective host responses to promote viral clearance and/or ameliorate inflammatory immunopathology.

Detection of flavivirus seroconversions in sentinel chicken flocks located throughout Australia is used to provide an early warning of increased levels of Murray Valley encephalitis (MVE) and Kunjin virus activity in the region. During the 2001/2002 season low levels of flavivirus activity were detected in northern Australia compared to previous years. MVE and Kunjin virus activity was detected in the Kimberley and Pilbara regions of Western Australia and the Northern Territory but not in north Queensland, New South Wales or Victoria. This is in contrast to the previous season when MVE activity was detected both in northern Australia and, for the first time in over 20 years, in New South Wales. Two cases of Murray Valley encephalitis were reported from the north of Western Australia during the 2001/2002 wet season.

Objectives: To estimate the prevalence of serological evidence of immunity to measles and rubella in preschool children in central and southern Sydney (NSW, Australia) and the prevalence of immunity in children with either documented or parentally reported immunization. Methods: Geographical cluster random sampling was used to select children aged between 18 and 60 months to participate in the present study. Standardized interviews obtained information on each child’s reported (by parents) immunization status and documentary evidence of immunization was recorded from the Personal Health Record. Venous blood was collected, serum was separated and stored frozen until tested. Measles and rubella antibodies were measured using ELISA, with either immunofluorescence or haemagglutination inhibition being used to clarify equivocal results. The study was conducted from 1992 to 1994 in conjunction with surveys of blood lead concentrations, iron status and micronutrient status. Results: Parents of 726 of 953 children identified between 9 and 60 months of age agreed to participate in the lead, immunization, iron status and micronutrient studies. Sufficient blood for antibody testing was obtained from 580 children, aged 18 to 62 months at the time of collection. Parents reported that 94.7% (95% confidence interval (CI) 92.7–96.5%) of children had received a measles–mumps or measles–mumps–rubella (MMR) immunization. General practitioners administered 72.8% of these immunizations. The prevalence of serological evidence of immunity to measles and rubella was 88.8% (95% CI 86.2–91.4%) and 91.9% (95% CI 89.6–94.2%), respectively. There was documented evidence of measles and rubella immunization for 88.4% (95% CI 85.7–91.2%) and 86.4% (95% CI 83.4–89.3%) of children, respectively. Of children with documented measles immunization, 91.6% (95% CI 89.2–94.0%) had detectable measles antibody. Of children with documented rubella immunization, 97.2% (95% CI 95.8–98.6%) had detectable rubella antibody. Conclusions: Measles and rubella immunization rates in central and southern Sydney are relatively high and most of these immunizations are provided by the private sector. Immunity to rubella in children with documented rubella immunization is at the level that would be expected from seroconversion studies. Immunity to measles in children with documented measles immunization is slightly lower than expected from seroconversion studies, highlighting the need for the second MMR immunization in preschool children, as well as making near universal immunization imperative if this disease is to be eradicated.

mosquito samples and/or detecting seroconversion to MVEVin sentinel chicken flocks. These surveillance systemsare intended to provide an early warning of MVEVactivity. Monitoring of meteorological events can alsogive a broad indication of likely vector and host activity,while climatic indices can be used in epidemic predictivemodelling.

The frequency of high (greater than 256) IgG anti-human herpesvirus type 6 (HHV-6) titers in sera known to be positive for IgM anti-cytomegalovirus (CMV) or IgM anti-Epstein Barr virus (EBV) was significantly greater than in sera from healthy controls or from a group of ill patients who were CMV and EBV IgM-negative (15/25 and 17/25 vs. 1/25 and 2/25, respectively, P less than .001). There was serologic evidence of simultaneous HHV-6 infection or reactivation (a rise in IgG anti-HHV-6 titer or the presence of IgM anti-HHV-6) in sera from 14 of 17 primary CMV infections. In 5 of the 10 patients with concurrent rises in IgG titers to both viruses, the rise in IgG anti-HHV-6 preceded that of IgG anti-CMV. Complete removal of IgG anti-CMV reactivity from 5 sera from patients who had a primary CMV infection with a rise in IgG anti-HHV-6 titer had no effect on the IgG anti-HHV-6 titer of those sera, demonstrating that the rise in HHV-6 IgG titer was not a consequence of anti-CMV antibodies cross-reacting in the HHV-6 IgG assay.

The earliest known reports of dengue fever, a mosquitoborne disease, are from China in 992 AD. During the 18th and 19th centuries, both the slave trade and increases in shipping and commercial trade saw the disease spread throughout the world via sailing ships. This spread was largely due to the water supplies stored on board ships, which provided an effective means of travel for the virus and vector that cause dengue fever.

West Nile virus is an arbovirus that has caused large outbreaks of febrile illness, meningitis and encephalitis in Europe, North America and the Middle East. We describe the first laboratory-confirmed human case of West Nile virus infection in Australia, in a 58-year-old tourist who was almost certainly infected in Israel. The case is a reminder of the need to consider exotic pathogens in travellers and of the risk of introducing new pathogens into Australia.