Dengue or Kokobera? A case report from the Top End of the Northern Territory

In early April 1998, the Centre for Disease Control in Darwin was notified of a possible case of dengue which appeared to have been acquired in the Northern Territory. Because dengue is not endemic to the Northern Territory, locally acquired infection has significant public health implications, particularly for vector identification and control to limit the spread of infection. Dengue IgM serology was positive on two occasions, but the illness was eventually presumptively identified as Kokobera infection. This case illustrates the complexity of interpreting flavivirus serology. Determining the cause of infection requires consideration of the clinical illness, the incubation period, the laboratory results and vector presence. Waiting for confirmation of results, before the institution of the public health measures necessary for a true case of dengue, was ultimately justified in this case. This is a valid approach in the Northern Territory, but may not be applicable to areas of Australia with established vectors for dengue

An outbreak investigation of paediatric severe acute respiratory infections requiring admission to intensive care units - Fiji, May 2016

Introduction Influenza-associated severe acute respiratory infections (SARI) are a major contributor to global morbidity and mortality. In response to a cluster of SARI cases and deaths in pregnant women, with two deceased cases testing positive for influenza A(H1N1)pdm09, an investigation was initiated to determine whether there was an increase of paediatric SARI cases admitted to divisional hospital intensive care units in Fiji in may 2016 compared to May 2013-2015. Methods Retrospective case finding was conducted at the paediatric intensive care units (PICUs) in Fiji's three divisional hospitals. Data were collected from 1 January 2013 to 26 May 2016. Cases were identified using a list of clinical diagnoses compatible with SARI. Results A total of 632 cases of paediatric SARI with complete details were identified. The median age of cases was 6 months (Interquartile range: 2-14 months). Children aged less than 5 years had a higher rate of paediatric SARI requiring admission to a divisional hospital PICU in May 2016 compared to May 2013-2015 (Incidence rate ratio: 1.7 [95% CI: 1.1-2.6]). This increase was not observed in children aged 5-14 years. The case-fatality ratio was not significantly different in 2016 compared to previous years. Conclusion The investigation enabled targeted public health response measures, including enhanced SARI surveillance at divisional hospitals and an emergency influenza vaccination campaign in the Northern Division

Evaluation of the early warning, alert and response system after Cyclone Winston, Fiji, 2016

To assess the performance of an early warning, alert and response system (EWARS) developed by the World Health Organization (WHO) – EWARS in a Box – that was used to detect and control disease outbreaks after Cyclone Winston caused destruction in Fiji on 20 February 2016

Murray Valley encephalitis virus surveillance and control initiatives in Australia.

Mechanisms for monitoring Murray Valley encephalitis (MVE) virus activity include surveillance of human cases, surveillance for activity in sentinel animals, monitoring of mosquito vectors and monitoring of weather conditions. The monitoring of human cases is only one possible trigger for public health action and the additional surveillance systems are used in concert to signal the risk of human disease, often before the appearance of human cases. Mosquito vector surveillance includes mosquito trapping for speciation and enumeration of mosquitoes to monitor population sizes and relative composition. Virus isolation from mosquitoes can also be undertaken. Monitoring of weather conditions and vector surveillance determines whether there is a potential for MVE activity to occur. Virus isolation from trapped mosquitoes is necessary to define whether MVE is actually present, but is difficult to deliver in a timely fashion in some jurisdictions. Monitoring of sentinel animals indicates whether MVE transmission to vertebrates is actually occurring. Meteorological surveillance can assist in the prediction of potential MVE virus activity by signalling conditions that have been associated with outbreaks of Murray Valley encephalitis in humans in the past. Predictive models of MVE virus activity for south-eastern Australia have been developed, but due to the infrequency of outbreaks, are yet to be demonstrated as useful for the forecasting of major outbreaks. Surveillance mechanisms vary across the jurisdictions. Surveillance of human disease occurs in all States and Territories by reporting of cases to health authorities. Sentinel flocks of chickens are maintained in 4 jurisdictions (Western Australia, the Northern Territory, Victoria and New South Wales) with collaborations between Western Australia and the Northern Territory. Mosquito monitoring complements the surveillance of sentinel animals in these jurisdictions. In addition, other mosquito monitoring programs exist in other States (including South Australia and Queensland). Public health control measures may include advice to the general public and mosquito management programs to reduce the numbers of both mosquito larvae and adult vectors. Strategic plans for public health action in the event of MVE virus activity are currently developed or being developed in New South Wales, the Northern Territory, South Australia, Western Australia and Victoria. A southern tri-State agreement exists between health departments of New South Wales, Victoria and South Australia and the Commonwealth Department of Health and Aged Care. All partners have agreed to co-operate and provide assistance in predicting and combatting outbreaks of mosquito-borne disease in south-eastern Australia. The newly formed National Arbovirus Advisory Committee is a working party providing advice to the Communicable Diseases Network Australia on arbovirus surveillance and control. Recommendations for further enhancement of national surveillance for Murray Valley encephalitis are described

Usefulness of a self-reported history of chickenpox in adult women in the Top End

Early determination of immune status is essential for the prevention and/or amelioration of disease following exposure to chickenpox. This is of particular significance for pregnant women because of the additional risks to the foetus or newborn.1 To determine the usefulness of a self-reported history of chickenpox in adult women in the Top End, we compared it with serological evidence of immunity

Ross River virus transmission in Darwin, Northern Territory, Australia

The alpha virus Ross River virus (RR) is responsible for most of the confirmed cases of arbovirus disease in Australia and is responsible for periodic outbreaks of arbovirus disease in the NT (Whelan et al. 1994, Merianos et al. 1992, Tai et al. 1993). A mosquito monitoring program utilising CO2 baited traps has been in place in Darwin since 1979. There are currently 17 traps set weekly in various positions in the Darwin suburban area between sources of mosquitoes and urban areas. The usual pattern of adult abundance is high Ae. vigilax (Skuse) numbers from September to January and high Cx. annulirostris Skuse numbers from January to June. This paper outlines the annual incidence of RR disease in the 3 residential regions of Darwin and examines the vector and environmental variables in various suburban groupings of urban Darwin to determine if they could help explain the distribution of cases and hence assist in the prediction of risk periods for proactive mosquito control or disease awareness programs

Ross River virus transmission in Darwin, Northern Territory, Australia

The alpha virus Ross River virus (RR) is responsible for most of the confirmed cases of arbovirus disease in Australia and is responsible for periodic outbreaks of arbovirus disease in the NT (Whelan et al. 1994, Merianos et al. 1992, Tai et al. 1993). A mosquito monitoring program utilising CO2 baited traps has been in place in Darwin since 1979. There are currently 17 traps set weekly in various positions in the Darwin suburban area between sources of mosquitoes and urban areas. The usual pattern of adult abundance is high Ae. vigilax (Skuse) numbers from September to January and high Cx. annulirostris Skuse numbers from January to June. This paper outlines the annual incidence of RR disease in the 3 residential regions of Darwin and examines the vector and environmental variables in various suburban groupings of urban Darwin to determine if they could help explain the distribution of cases and hence assist in the prediction of risk periods for proactive mosquito control or disease awareness programs.Date:199

The challenges of global case reporting during pandemic A(H1N1) 2009

During the 2009 A(H1N1) influenza pandemic, the World Health Organization (WHO) asked all Member States to provide case-based data on at least the first 100 laboratory-confirmed influenza cases to generate an early understanding of the pandemic and provide appropriate guidance to affected countries. In reviewing the pandemic surveillance strategy, we evaluated the utility of case-based data collection and the challenges in interpreting these data at the global level. To do this, we assessed compliance with the surveillance recommendation and data completeness of submitted case records and described the epidemiological characteristics of up to the first 110 reported cases from each country, aggregated into regions. From April 2009 to August 2011, WHO received over 18000 case records from 84 countries. Data reached WHO at different time intervals, in different formats and without information on collection methods. Just over half of the 18000 records gave the date of symptom onset, which made it difficult to assess whether the cases were among the earliest to be confirmed. Descriptive epidemiological analyses were limited to summarizing age, sex and hospitalization ratios. Centralized analysis of case-based data had little value in describing key features of the pandemic. Results were difficult to interpret and would have been misleading if viewed in isolation. A better approach would be to identify critical questions, standardize data elements and methods of investigation, and create efficient channels for communication between countries and the international public health community. Regular exchange of routine surveillance data will help to consolidate these essential channels of ommunication