Achieving high immunisation rates amongst children in the Australian Capital Territory: a collaborative effort.

BACKGROUND: In September 2008 the ACT achieved the highest childhood coverage rates in Australia with rates of 93.5% (12-15-month age cohort), 94.9% (24-27-month age cohort) and 90.58% (60-63-month age cohort). PURPOSE: To analyse the key contributing factors and policy initiatives that have likely to have led to high childhood immunisation rates in the ACT. METHODS: Data used in this report were sourced from the Australian Childhood Immunisation Register (ACIR) held at Medicare Australia, General Practice Immunisation Incentives (GPII) 'calculation' data held at ACT Division of General Practice and internal immunisation databases held at Health Protection Service. OUTCOMES: Although the reasons for the high coverage rates seen in children are multi factorial (including national and consumer factors), key reasons locally in the ACT include: (a) the implementation of an ACT-wide immunisation strategy; (b) proactive follow up of children overdue for immunisation; (c) more sustainable provision of immunisation services across both public and private health providers; and (d) a centralised vaccine delivery service and 'cold chain' monitoring system. CONCLUSIONS: Although nationwide immunisation policy has been successful in increasing childhood coverage rates across all Australian jurisdictions, it is important to also acknowledge local factors that have likely to have contributed to the successful implementation of the Immunise Australia Program at the coal face.

Public health management of increased incidence of meningococcal disease in the Australian Capital Territory: 2003 to 2004.

This paper describes a sudden increase of meningococcal notifications in the Australian Capital Territory within a 3 month period, and the public health strategies used to manage it. There were 15 cases of meningococcal disease notified to the Communicable Disease Control (CDC) section, Australian Capital Territory Health (ACT Health), between 6 November 2003 and 5 February 2004. This was much higher than the annual average of 6 cases. The cases were notified in 2 clusters. The first cluster of 8 cases, all serogroup C, was notified between 6 November to 8 December 2003. Seven of these cases had an identical phenotype C:2a:P1.4 suggesting a common source. The second cluster of 7 cases was notified between 30 December 2003 and 5 February 2004. Of these, 5 were serogroup B, 1 was serogroup W-135 and 1 was serogroup C, whose phenotype (C:2a:P1.4) was identical to the phenotype of the first cluster of serogroup C cases. Phenotypes were not available for the serogroup B cases. There were 4 main interventions developed to manage the increased incidence based on the epidemiology of the cases; these were implemented concurrently. Factors that supported investigation and management were good surveillance systems, quick turnover of laboratory tests, regular communication with relevant health agencies and maintaining public awareness. As the number of cases notified was much higher than the annual average, the possibility of a community outbreak was considered. The Guidelines for the Early Clinical and Public Health Management of Meningococcal Disease in Australia (national guidelines) were consulted to determine whether there was an outbreak and the influence this had on management is also discussed.

Seasonal variation in acute hospital admissions and emergency room presentations among children in the Australian Capital Territory.

AIM: To examine seasonal variation in hospital use for five paediatric conditions of the Australian Capital Territory residents. METHODS: Hospital admissions (1993-2004) and emergency room (ER) presentations (1999-2004) for asthma, croup, bronchiolitis, other respiratory conditions and diarrhoea of children aged <5 years were compared by month and season. RESULTS: The five conditions comprised 14% of admissions and 24% of ER presentations of children aged <5 years. Bronchiolitis (both admissions and ER presentations) were the highest in the 0-1 year age group (>80%) and the other four conditions peaked at 1-2 years. Children aged 0-2 years contributed 66% of diarrhoea, 62% of croup and 44% of other respiratory admissions whereas ER presentations were higher for other respiratory conditions (57%) and lower for croup (47%). Boys showed higher rates of admissions and ER presentations for all conditions except diarrhoea. Strong seasonal associations were apparent. Incident rate ratios of admissions were significantly higher in autumn compared with summer for asthma and croup whereas bronchiolitis and other respiratory conditions admissions were the highest in winter. Diarrhoea admissions were the highest in spring. ER presentations of the five conditions also showed similar associations with season. CONCLUSION: Hospital admissions and ER presentations of these five conditions showed strong seasonal patterns, knowledge of which could contribute to improved resource planning (staffing) to meet expected increases in demand for services and scheduling of elective admissions. These findings could be extended to develop a model for forecasting hospital use and to explore the causes of these diseases to ameliorate seasonal effects.

The epidemiology of pertussis in the Australian Capital Territory, 1999 to 2005--epidemics of testing, disease or false positives?

The increase in pertussis notifications since the 1990s in many countries, including Australia, has been attributed to improved diagnosis. This study aimed to describe the epidemiology of pertussis in the Australian Capital Territory from 1999 to 2005, determine whether the apparent changes could be accounted for by greater recognition and testing, and explore the impact of false positive serology results associated with faulty test kits. The Australian Capital Territory resident notification, laboratory and separation data from 1999 to 2005 were examined and the proportions of positive tests across time periods and age groups compared. Notification rates increased in the years 2000, 2003 and 2005. There was a shift in the age distribution of cases, from children and teenagers in 2000, to teenagers in 2003 and adults in 2005. Testing activity and notification activity were closely related. Comparing the epidemic periods to the preceding inter-epidemic periods, the proportion of positive tests was maintained or increased for all age groups combined and for adults and children (e.g. statistically significant increase from 7.8% to 14.0% in the 2005 epidemic in adults). During each epidemic the proportion of positive tests was statistically significantly higher in the age group with the highest notification activity. Despite similar testing rates in adults in 2003 and 2005, greater disease activity was reported in 2005. Although the numbers were small, polymerase chain reaction and culture positive test results increased in 2003 but not in 2005. The proportion of positive polymerase chain reaction results increased in 2003, providing strong evidence that the apparent epidemic of 2003 was due to a true increase in underlying disease activity. Because of the uncertainty surrounding the timing of the false positive serology results, the study provides weaker support for a true epidemic of pertussis in 2005.

Early warning of Ross River virus epidemics: combining surveillance data on climate and mosquitoes.

BACKGROUND: Ross River virus disease is spread by mosquitoes, and an average of 5000 people are infected each year in Australia. It is one of the few infectious diseases for which climate-based early warning systems could be developed. The aim of this study was to test whether supplementing routinely collected climate data with mosquito surveillance data could increase the accuracy of disease prediction models. METHODS: We focused on a temperate region of Western Australia between July 1991 and June 1999. We developed "early" and "later" warning logistic regression models to test the sensitivity of data on climate (tide height, rainfall, sea surface temperature) and mosquito counts for predicting epidemics of disease. RESULTS: Climate data on their own were moderately sensitive (64%) for predicting epidemics during the early warning period. Addition of mosquito surveillance data increased the sensitivity of the early warning model to 90%. The later warning model had a sensitivity of 85%. CONCLUSIONS: We found that climate data are inexpensive and easy to collect and allow the prediction of Ross River virus disease epidemics within the time necessary to improve the effectiveness of public health responses. Mosquito surveillance data provide a more expensive early warning but add substantial predictive value.

An evaluation of public health interventions during a pertussis outbreak in the ACT, 2003.

OBJECTIVE: To assess whether issuing information alerts increased the proportion of pertussis cases notified within the 21-day infectious period during a pertussis outbreak in the Australian Capital Territory (ACT) in 2003. METHOD: The study included all persons resident in the ACT for whom a notification of pertussis was received with onset of disease between 1 March and 31 December 2003. Cases notified within 21 days of onset were called 'early notifications'. The effectiveness of information alerts was assessed by comparing the proportion of early notifications before and after each alert and over the course of the outbreak. MAIN OUTCOME MEASURE: The proportion of early notifications. RESULTS: The proportion of early notifications ranged from 1/36 (2.7%) prior to the first intervention to 29/52 (55.7%) after the final intervention (p < 0.001). CONCLUSIONS: This study supports the hypothesis that information alerts by ACT Health increase the proportion of cases notified within the infectious period of 21 days. IMPLICATIONS FOR PUBLIC HEALTH PRACTICE: Early diagnosis of pertussis cases (within the infectious period) has the potential to limit transmission and protect susceptible infants.

SARS and biothreat preparedness--a survey of ACT general practitioners.

In late 2003 and early 2004 the ACT Division of General Practice and ACT Health conducted two concurrent surveys designed to identify knowledge, attitudes and practices of Australian Capital Territory (ACT) general practitioners around severe acute respiratory syndrome (SARS) and biothreat preparedness. One survey asked individual general practitioners (GPs) about how they gathered information about SARS in 2003, how they preferred to receive information, current practices, and how they perceived the threat of SARS and other infectious agents. The second survey asked practice principals how they organised their practice to respond to the SARS threat in 2003, any difficulties they had with implementing this response, use of SARS infection control guidelines and current policies. The response rate for the individual GP survey was 48 per cent (184/381) and the response rate for the practice organisation survey was 54 per cent (74/136). GPS used many sources of information on SARS during the 2003 outbreak. Facsimiles from the ACT Division of General Practice were the primary source (17%) and facsimile was the preferred method of receiving information in future outbreaks. The majority of GP respondents felt adequately informed about SARS during the 2003 outbreak, but many general practices did not follow the national guidelines on telephone screening of patients, warning signs and having infection control kits available. The majority of practices reported that they had policies or procedures in place to isolate potentially infectious patients from others in the waiting room. GPs rated an influenza pandemic as a threat to themselves and their patients much more highly than SARS or bioterrorism. Suggestions and comments on how ACT GPs could be better prepared to respond to future outbreaks included the need for timeliness of information, information delivery mechanisms, communication issues, education, the availability of guidelines and protocols, planning, role delineation, the use of response teams, provision of equipment, and vaccination. Planning for future infectious disease outbreak events in the Australian Capital Territory should incorporate general practitioners so that the plans reflect what is a feasible response in the general practice setting.

An outbreak of Legionnaires' disease at the Melbourne Aquarium, April 2000: investigation and case-control studies.

OBJECTIVE: To investigate the source and risk factors associated with Australia's largest outbreak of Legionnaires' disease. DESIGN AND SETTING: Epidemiological and environmental investigation of cases of Legionnaires' disease associated with visits to the Melbourne Aquarium; two case-control studies to confirm the outbreak source and to investigate risk factors for infection, respectively. PARTICIPANTS: Patients with confirmed Legionnaires' disease who visited the Melbourne Aquarium between 11 and 27 April 2000 were compared (i) with control participants from the community, and (ii) with control participants selected from other visitors to the Aquarium during this period. MAIN OUTCOME MEASURES: Risk factors for acquiring Legionnaires' disease. RESULTS: There were 125 confirmed cases of Legionnaires' disease caused by Legionella pneumophila serogroup 1 associated with the Aquarium; 76% of patients were hospitalised, and four (3.2%) died. The Aquarium cooling towers were contaminated with this organism. Visiting the Aquarium was significantly associated with disease (odds ratio [OR], 207; 95% CI, 73-630). The case-control study indicated that current smoking was a dose-dependent risk (multivariable OR for currently smoking > 70 cigarettes/week, 13.5; 95% CI, 5-36), but chronic illness and duration of exposure at the site were not significant risks. CONCLUSIONS: This study showed an association between poorly disinfected cooling towers at the Aquarium and Legionnaires' disease in visitors, and confirmed current smoking as a critical risk factor. The rapid response, publicity, and widespread urinary antigen testing may have resulted in detection of milder cases and contributed to the relatively low apparent morbidity and mortality rates. The urinary antigen test allows rapid identification of cases and may be changing the severity of illness recognised as Legionnaires' disease and altering who is considered at risk.

A review of national legionellosis surveillance in Australia, 1991 to 2000.

A study was undertaken to analyse legionellosis notifications for the period 1991 to 2000 to establish the distribution of legionellosis in Australia with the aim of identifying risk factors amenable to public health intervention. Legionellosis notification rates ranged from 0.6 cases per 100,000 population in 1991 to 2.5 cases per 100,000 population in 2000. Notifications were highest in autumn (March to May). Sixty-nine per cent of cases were males. At-risk population included those aged over 50 years. The upward trend in notification rates of legionellosis indicated that this disease remains a significant public health problem particularly among older people. Seasonal differences in notification rates require further investigation to develop appropriate prevention and control strategies. To have a better understanding of the epidemiology of legionellosis, further information is needed on smoking history, chronic illnesses, whether the notification is outbreak-related and the species of Legionella isolated.

Predicting Ross River virus epidemics from regional weather data.

BACKGROUND: Diseases caused by arboviruses cause extensive mortality and morbidity throughout the world. Weather directly affects the breeding, abundance, and survival of mosquitoes, the principal vector of many arboviruses. The goal of this study was to test whether climate variables could predict with high levels of accuracy (more than 70%) epidemics of one arbovirus, Ross River virus disease. METHODS: Weather data from two regions in southeastern Australia were matched with Ross River virus disease data for the period 1991 to 1999. Our aim was to develop simple models for the probability of the occurrence of an epidemic in an area in a given year. RESULTS: Two predictable epidemic patterns emerged, after either high summer rainfalls or high winter rainfalls. A prerequisite relating to host-virus dynamics was lower than average spring rainfall in the preepidemic year. The sensitivity of the model was 96% for Region 1 and 73% for Region 2. CONCLUSIONS: Early warning of weather conditions conducive to outbreaks of Ross River virus disease is possible at the regional level with a high degree of accuracy. Our models may have application as a decision tool for health authorities to use in risk-management planning.

An outbreak of Salmonella typhimurium PTI35 gastroenteritis associated with a minimally cooked dessert containing raw eggs.

In April 2000, we investigated an outbreak of gastroenteritis amongst attendees of a local community dinner in a Perth suburb. Of the 98 people interviewed (response rate 98%), 53 reported gastrointestinal symptoms (attack rate 54%). Faecal cultures from 11 cases, 2 food preparers, 1 waitress and leftover mock ice-cream dessert grew Salmonella Typhimurium PT135. Of the 3 food handlers, one was asymptomatic, another gave an unclear history of onset of illness and the waitress claimed illness onset 9 days after the dinner. A cohort study implicated fruit salad (RR 1.64 [95% CI: 1.05-2.58], p=0.017) and/or mock ice-cream dessert (RR 1.78 [95% CI: 0.91-3.52], p=0.045). Eggs used to make the mock ice-cream dessert were supplied directly from the producer who used inappropriate shell cleaning methods. The method of preparation of the dessert encouraged contamination. Salmonella species were not isolated in poultry faecal samples collected from the implicated egg farm. The cause of this outbreak was almost certainly the ice-cream dessert with contamination most likely resulting either from the eggs used to make the dessert or one or both of the food preparers, coupled with inadequate cooking of the dessert. Eggs used in preparing food for mass consumption should be sourced from distributors with approved cleaning procedures. Furthermore, pasteurised egg products or egg pulp should be used in the preparation of uncooked or minimally cooked dishes.

Norwalk-like virus outbreak in Canberra: implications for infection control in aged care facilities.

This paper reports on an outbreak of viral gastroenteritis in three institutions (two aged care facilities and one hospital) in Canberra during the winter of 2002. Norwalk-like virus genotype II was detected in samples from staff and/or residents in all three institutions. A case series investigation was conducted amongst both staff and residents. It is likely that the outbreaks in the three institutions were linked due to transfers of infected residents from one institution to another, early in the outbreak. A total of 281 cases were identified during the outbreak, which lasted 32 days. Attack rates in the three institutions were 46.3 per cent, 52.7 per cent and 55.2 per cent respectively. Person-to-person spread and/or airborne transmission were postulated as modes of transmission in all three institutions. Infection control practices in each of the aged care institutions were of an acceptable standard for accreditation, but were inadequate to control further spread of the outbreak within and between institutions. Outbreak management plans should be a part of the infection control standards for accreditation of aged care facilities.