Epidemiology of Shiga toxin producing Escherichia coli in Australia, 2000-2010.

BACKGROUND: Shiga toxin-producing Escherichia coli (STEC) are an important cause of gastroenteritis in Australia and worldwide and can also result in serious sequelae such as haemolytic uraemic syndrome (HUS). In this paper we describe the epidemiology of STEC in Australia using the latest available data. METHODS: National and state notifications data, as well as data on serotypes, hospitalizations, mortality and outbreaks were examined. RESULTS: For the 11 year period 2000 to 2010, the overall annual Australian rate of all notified STEC illness was 0.4 cases per 100,000 per year. In total, there were 822 STEC infections notified in Australia over this period, with a low of 1 notification in the Australian Capital Territory (corresponding to a rate of 0.03 cases per 100,000/year) and a high of 413 notifications in South Australia (corresponding to a rate of 2.4 cases per 100,000/year), the state with the most comprehensive surveillance for STEC infection in the country. Nationally, 71.2% (504/708) of STEC infections underwent serotype testing between 2001 and 2009, and of these, 58.0% (225/388) were found to be O157 strains, with O111 (13.7%) and O26 (11.1%) strains also commonly associated with STEC infections. The notification rate for STEC O157 infections Australia wide between 2001-2009 was 0.12 cases per 100,000 per year. Over the same 9 year period there were 11 outbreaks caused by STEC, with these outbreaks generally being small in size and caused by a variety of serogroups. The overall annual rate of notified HUS in Australia between 2000 and 2010 was 0.07 cases per 100,000 per year. Both STEC infections and HUS cases showed a similar seasonal distribution, with a larger proportion of reported cases occurring in the summer months of December to February. CONCLUSIONS: STEC infections in Australia have remained fairly steady over the past 11 years. Overall, the incidence and burden of disease due to STEC and HUS in Australia appears comparable or lower than similar developed countries.

MLVA and phage typing as complementary tools in the epidemiological investigation of Salmonella enterica serovar Typhimurium clusters.

In South Australia serotyping and phage typing are employed for routine Salmonella surveillance. Molecular techniques such as Multiple-locus variable number tandem repeat analysis (MLVA) are increasingly utilized to aid outbreak investigations. During 2007 three Salmonella enterica serovar Typhimurium outbreaks involving phage types DT9, DT29, and DT44 were investigated. Human, food and environmental isolates were also typed by MLVA. In the DT9 outbreak cluster MLVA demonstrated distinct groupings that corresponded to epidemiological differences in time, place, and descriptive information on potential transmission mechanisms. In contrast, the human and food isolates of both the DT29 and DT44 clusters had identical MLVA profiles for all but one case. These data correlated with the epidemiology suggesting that these isolates were closely related and probably a single agent. These findings illustrate that phage typing and MLVA can provide different but complementary information for epidemiological investigations of Salmonella outbreaks.

Economic costs of Shiga toxin-producing Escherichia coli infection in Australia.

Shiga toxin-producing Escherichia coli (STEC) infections are an important cause of foodborne disease in Australia. Three percent to 7% of sporadic patients develop hemolytic uremic syndrome (HUS) and 40% of patients with HUS develop chronic complications. To examine costs associated with illness, we interviewed patients notified to the South Australian Department of Health with a structured questionnaire regarding severity of illness, medical treatment, time lost from work, hospitalization, and other costs. In 2003-2006, we interviewed 46 patients of STEC infection, 2 of whom developed HUS. The median duration of illness was 7 days (range 3-31 days) and 41% (19/46) of patients were admitted to hospital. The estimated total cost for the 46 STEC cases in South Australia was AUD$144,087, equating to a mean cost of AUD$3132 per case. We estimate that the annual total costs of STEC infection in South Australia and Australia are AUD$200,283 and AUD$2,633,181, respectively. We used linear regression to identify that STEC infection costs increase by AUD$608 per day regardless of severity, and that more severe illness is strong predictor of cost. This is the first Australian study to examine costs of STEC infection and highlights the significant impact of this illness.

Food- and waterborne disease outbreaks in Australian long-term care facilities, 2001-2008.

Abstract Food- or waterborne diseases in long-term care facilities (LTCF) can result in serious outcomes, including deaths, and they are potentially preventable. We analyzed data collected by OzFoodNet on food- and waterborne disease outbreaks occurring in LTCF in Australia from 2001 to 2008. We compared outbreaks by the number of persons affected, etiology, and implicated vehicle. During 8 years of surveillance, 5.9% (55/936) of all food- and waterborne outbreaks in Australia occurred in LTCF. These LTCF outbreaks affected a total of 909 people, with 66 hospitalized and 23 deaths. The annual incidence of food- or waterborne outbreaks was 1.9 (95% confidence intervals 1.0-3.7) per 1000 facilities. Salmonella caused 17 outbreaks, Clostridium perfringens 14 outbreaks, Campylobacter 8 outbreaks, and norovirus 1 outbreak. Residents were at higher risk of death during outbreaks of salmonellosis than for all other outbreaks combined (relative risk 7.8, 95% confidence intervals 1.8-33.8). Of 15 outbreaks of unknown etiology, 11 were suspected to be due to C. perfringens intoxication. Food vehicles were only identified in 27% (14/52) of outbreaks, with six outbreak investigations implicating pureed foods. Dishes containing raw eggs were implicated as the cause of four outbreaks. Three outbreaks of suspected waterborne disease were attributed to rainwater collected from facility roofs. To prevent disease outbreaks, facilities need to improve handling of pureed foods, avoid feeding residents raw or undercooked eggs, and ensure that rainwater tanks have a scheduled maintenance and disinfection program.

Serogroup-specific risk factors for Shiga toxin-producing Escherichia coli infection in Australia.

BACKGROUND: Shiga toxin-producing Escherichia coli (STEC) is an important cause of foodborne illness. In Australia, risk factors for STEC infection have not been examined at a national level. METHODS: We conducted a case-control study in 6 Australian jurisdictions from 2003 through 2007. A case patient was defined as a person from whom STEC was isolated or toxin production genes were detected in stool. Case patients were recruited from notifiable disease registers, and 3 control subjects frequency matched by age were selected from databases of controls. Using structured questionnaires, interviewers collected data on clinical illness, foods consumed, and exposures to potential environmental sources. RESULTS: We recruited 43 case patients infected with STEC serogroup O157, 71 case patients infected with non-O157 serogroups, and 304 control subjects. One patient infected with serogroup O157 and 7 infected with non-O157 serogroups developed hemolytic uremic syndrome. Compared with control subjects, case patients infected with STEC O157 were more likely to eat hamburgers, visit restaurants, have previously used antibiotics, or have family occupational exposure to red meat. Case patients infected with non-O157 STEC were more likely to eat sliced chicken meat or corned beef from a delicatessen, camp in the bush, eat catered meals, or have family occupational exposure to animals. Negative associations were observed for certain foods, particularly homegrown vegetables, fruits, or herbs. CONCLUSION: This study of risk factors for STEC infection by serogroup highlights risks associated with eating hamburgers and occupational handling of raw meat. To prevent infection, hamburgers must be cooked thoroughly, and people handling raw meat or who have close contact with animals must ensure adequate hygiene.

Estimating community incidence of Salmonella, Campylobacter, and Shiga toxin-producing Escherichia coli infections, Australia.

To estimate multipliers linking surveillance of salmonellosis, campylobacteriosis, and Shiga toxin-producing Escherichia coli (STEC) infections to community incidence, we used data from a gastroenteritis survey and other sources. Multipliers for severe (bloody stool/long duration) and milder cases were estimated from the component probabilities of doctor visit, stool test, sensitivity of laboratory test, and reporting to surveillance system. Pathogens were classified by the same severity criteria and appropriate multipliers applied. Precision of estimates was quantified by using simulation techniques to construct 95% credible intervals (CrIs). The multiplier for salmonellosis was estimated at 7 (95% CrI 4-16), for campylobacteriosis at 10 (95% CrI 7-22), and for STEC at 8 (95% CrI 3-75). Australian annual community incidence rates per 100,000 population were estimated as 262 (95% CrI 150-624), 1,184 (95% CrI 756-2,670), and 23 (95% CrI 13-54), respectively. Estimation of multipliers allows assessment of the true effects of these diseases and better understanding of public health surveillance.

Influenza B outbreak in a primary school in Adelaide, Australia, 2011.

INTRODUCTION: This report describes a 2011 seasonal influenza B outbreak in a metropolitan primary school in Australia with 179 students. METHODS: Epidemiological, microbiological and environmental investigations were undertaken. A retrospective cohort study was conducted using a questionnaire that included demographic data, details of illness, chronic health conditions and vaccination status. Influenza-like illness (ILI) was defined as fever plus cough and/or sore throat. Analysis of ILI was undertaken with the χ(2) test and Fisher's exact test. RESULTS: Seventy-two questionnaire respondents (75%) reported illness during the outbreak - 43 with ILI, giving an attack rate of 45%. There was no association between ILI and age or chronic lung disease. Six (6%) students were vaccinated against influenza before the outbreak; although four became ill, none satisfied the ILI case definition. Seven students were positive for influenza B including two confirmed as B/Brisbane/60/2008-like; one student was positive for rhinovirus and another for metapneumovirus. The recommended influenza vaccine matched the circulating influenza strains. DISCUSSION: This cohort study estimated a high ILI attack rate and demonstrated low influenza vaccine coverage within the setting of a primary school. Gastrointestinal symptoms, in addition to constitutional and respiratory symptoms, were common.

Pneumococcal disease in South Australia: vaccine success but no time for complacency.

BACKGROUND: Trends in age specific and serotype specific incidence rates for invasive pneumococcal disease (IPD) were examined in South Australia 4 years before and 5 years after the commencement of the Australian universal childhood 7 valent pneumococcal conjugate vaccine (7vPCV) program. METHODS: IPD cases were identified by routine enhanced surveillance. IPD serotypes were grouped according to those covered by the 7vPCV, the six serotypes specific to the 13 valent pneumococcal conjugate vaccine (13vPCV), the 11 serotypes specific to the 23 valent pneumococcal polysaccharide vaccine (23vPPV), as well as non-13vPCV and non-23vPPV groups. Poisson regression was used to calculate age-specific and serotype-specific incident rate ratios (IRRs) comparing pre (2002-2004) and post (2007-2009) universal childhood 7vPCV periods. RESULTS: Following the introduction of the 7vPCV program, the rate of IPD in children aged <2 years decreased by 81% for all serotypes (IRR 0.19, 95% CI, 0.13-0.28) and by 98% for 7vPCV serotypes (IRR 0.02, 95% CI, 0.007-0.07). At the same time, there was some evidence for an increase in IPD caused by 13vPCV specific serotypes (IRR 1.58, 95% CI, 0.78-3.21) and non-13vPCV serotypes (IRR 1.80, 95% CI, 0.45-7.21). Among adults aged ≥65 years, overall there was a 27% reduction in IPD caused by all serotypes following introduction of the 7vPCV program (IRR 0.73, 95% CI, 0.58-0.93). However, the rate of IPD increased in the last 2 years of the study period. The initial decrease was a result of a 74% reduction in the rate of IPD due to 7vPCV serotypes (IRR 0.26, 95% CI, 0.17-0.40). At the same time, the rate of IPD increased for 13vPCV specific serotypes (IRR 1.55, 95% CI, 0.94-2.54), 23vPPV specific serotypes (IRR 1.91, 95% CI, 0.99-3.71) and particularly non-23vPPV serotypes (IRR 5.3, 95% CI, 1.83-15.34). CONCLUSION: There has been a large direct and sustained benefit from the universal 7vPCV program in children, particularly those aged <2 years, with some evidence for serotype replacement. There is also good evidence that the childhood program has provided indirect benefits to adults aged ≥65 years, although serotype replacement has reduced the initial benefits.

Salmonella in chicken meat, eggs and humans; Adelaide, South Australia, 2008.

Varieties of Salmonella enterica are the second most commonly notified causes of gastroenteritis in Australia. Outbreaks of Salmonella infection are commonly linked to food, particularly foods containing chicken meat and eggs. A number of European countries have introduced interventions based on Salmonella surveillance systems in the food industry and these have led to subsequent decreases in notification rates in humans. A descriptive case-series of human Salmonella infections notified in metropolitan Adelaide, South Australia, was conducted in 2008. Human Salmonella serotypes identified were then compared to serotypes identified from a retail chicken and egg survey conducted over the same time period in Adelaide. Ninety-four human cases of salmonellosis were included in the study. Thirty-one serotypes were identified and 61.7% of these were Salmonella enterica serovar Typhimurium (S. Typhimurium). In the week prior to illness, 62.8% of participants reported eating chicken and 47.9% reported eating eggs. Salmonella was identified in 38.8% of retail chicken samples; S. Infantis and S. Typhimurium phage type 135a were most commonly identified. No egg contents were found to contain Salmonella, but the pathogen was isolated on 3.5% of egg external surface samples. Eleven serotypes were common to both chicken and human samples, two serotypes were common to eggs and humans, and one serotype (S. Infantis) was common to all three sources. Serotypes of Salmonella isolated from chicken and egg samples included serotypes that were also isolated from humans, in cases included in this study, and in outbreaks previously investigated within Australia. Poultry meat and eggs are potential sources of introducing a defined range of human pathogens into South Australian kitchens. Ongoing systematic surveillance of animals and their food products, at farm and retail level for Salmonella could provide more definitive evidence of links between food sources and human infections; and also allow accurate measurement of interventions taken to reduce rates of Salmonella isolations in animal-based foods.

Outbreak of Salmonella typhimurium phage type 44 infection among attendees of a wedding reception, April 2009.

On 30 April 2009, the Communicable Disease Control Branch (CDCB) South Australia was notified of a Salmonella infection in a person who attended a wedding reception on 25 April 2009. Several other attendees reported becoming unwell with a similar gastrointestinal illness. The CDCB commenced an investigation to: characterise the outbreak in terms of person, place and time; identify probable source or sources; and implement control measures. A retrospective cohort study was undertaken among wedding reception attendees. A questionnaire collecting information on demographics, illness and menu items consumed was given to the majority of attendees. An environmental inspection of the wedding reception premise and food supplier premise, including food sampling was conducted to identify plausible sources of infection. The questionnaire response rate was 77%, from which an attack rate of 20% was calculated. There was a significant association between consumption of garlic aioli and illness (OR 5.4, 95% CI: 1.6, 18.1). Nine wedding reception attendees' stool samples tested positive for Salmonella Typhimurium phage type 44. A sample of garlic aioli also tested positive for Salmonella Typhimurium phage type 44. The ingredients of the garlic aioli included raw egg yolk, roasted garlic, Dijon mustard, vinegar and vegetable oil. The raw egg yolk was identified as a high risk food item; however no eggs tested positive for Salmonella.

The burden of influenza in healthy children in South Australia.

OBJECTIVE: To describe the influenza-related morbidity and mortality in healthy children aged under 5 years in South Australia, in order to further understand the potential role of influenza vaccination. DESIGN AND SETTING: We undertook a descriptive analysis of SA hospital separations data and Australian Bureau of Statistics death data for children aged under 5 years admitted to hospital for influenza. All diagnoses related to an influenza admission were examined to determine whether children were at risk of complications from influenza, according to the criteria of the National Health and Medical Research Council. MAIN OUTCOME MEASURES: Mean influenza admission rates per 100 000 population per year in children aged under 5 years between 1996 and 2006, and the proportion of children admitted to hospital who did not have a secondary diagnosis putting them at higher risk of influenza-related complications. RESULTS: From 1996 to 2006, 649 children aged under 5 years were admitted to hospital for influenza. Mean annual admission rates per 100 000 were highest in children aged under 1 year (151.0), and decreased with age. Aboriginal and Torres Strait Islander children aged under 5 years had a mean admission rate of 161.8 per 100 000. Most children under 5 years (81%) admitted to hospital did not have an underlying illness that would put them at risk of influenza-related morbidity. CONCLUSION: Healthy children aged under 2 years and Aboriginal and Torres Strait Islander children under 5 years old have high rates of hospital admission, which may have implications for the target group recommendations for influenza immunisation. Currently, vaccination is recommended only for children with specified chronic diseases.

Influenza B outbreak in a primary school in Adelaide, Australia, 2011

Introduction: This report describes a 2011 seasonal influenza B outbreak in a metropolitan primary school in Australia with 179 students. Methods: Epidemiological, microbiological and environmental investigations were undertaken. A retrospective cohort study was conducted using a questionnaire that included demographic data, details of illness, chronic health conditions and vaccination status. Influenza-like illness (ILI) was defined as fever plus cough and/or sore throat. Analysis of ILI was undertaken with the chi-squared test and Fisher’s exact test. Results: Seventy-two questionnaire respondents (75%) reported illness during the outbreak – 43 with ILI, giving an attack rate of 45%. There was no association between ILI and age or chronic lung disease. Six (6%) students were vaccinated against influenza before the outbreak; although four became ill, none satisfied the ILI case definition. Seven students were positive for influenza B including two confirmed as B/Brisbane/60/2008-like; one student was positive for rhinovirus and another for metapneumovirus. The recommended influenza vaccine matched the circulating influenza strains. Discussion: This cohort study estimated a high ILI attack rate and demonstrated low influenza vaccine coverage within the setting of a primary school. Gastrointestinal symptoms, in addition to constitutional and respiratory symptoms, were common.

Surveillance of Shiga toxigenic Escherichia coli in Australia.

All Australian States and Territories have low rates (< or = 0.32 cases per 100,000 population) of notification for Shiga toxin-producing Escherichia coli (STEC), except for South Australia where the rates are ten-fold higher at 2.58 cases per 100,000 population. To explore possible reasons for the variation in rates we surveyed public health reference laboratories to determine the methods used and number of specimens tested for these organisms. Only five of eight jurisdictions routinely conducted testing for STEC, and polymerase chain based tests were most common. Culture was also common and in one jurisdiction that tests specimens with culture, approximately 1.2 per cent of specimens were positive. The notification rates for different jurisdictions reflected the number of specimens tested, with jurisdiction testing < or = 500 specimens having rates < or = 0.32 cases per 100,000 population. The use of culture as a test method may also influence notification rates. Public health agencies must consider the number of specimens tested in interpreting surveillance data.

Information and support for women following the primary treatment of breast cancer.

OBJECTIVE: To examine the need for, use of and satisfaction with information and support following primary treatment of breast cancer. DESIGN: Cross-sectional survey. PARTICIPANTS: Cohort of 266 surviving women diagnosed with breast cancer over a 25-month period at a tertiary hospital, Adelaide, Australia. Time since diagnosis ranged from 6 to 30 months. MAIN OUTCOME MEASURES: Need for, use of and satisfaction with information and support. RESULTS: Women reported high levels of need for information about a variety of issues following breast cancer treatment. Ninety-four percentage reported a high level of need for information about one or more issues, particularly recognizing a recurrence, chances of cure and risk to family members of breast cancer. However, few women (2-32%) reported receiving such information. The most frequently used source of information was the surgeon followed by television, newspapers and books. The most frequently used source of support was family followed by friends and the surgeon. Few women (<7%) used formal support services or the Internet. Women were very satisfied with the information and support that they received from the surgeon and other health professionals but reported receiving decreasing amounts of information and support from them over time. CONCLUSIONS: Women experience a high need for information about breast cancer related issues following primary treatment of breast cancer. These needs remain largely unmet as few women receive information about issues that concern them. The role of the surgeon and other health professionals is critical in narrowing the gap between needing and receiving information.

An outbreak of Campylobacter jejuni infection among conference delegates.

Campylobacter infection is one of the most commonly reported foodborne diseases in Australia however, reported Campylobacter outbreaks are rare. This report describes such an outbreak among delegates attending a 10 day international academic meeting in South Australia during May 2001. A retrospective cohort study of the 29 delegates who attended the conference was conducted. A questionnaire was sent by email with a response rate of 93 per cent. Ten cases (onset of diarrhoea while attending the conference) were identified. Two were culture positive for Campylobacter jejuni. There was a significant association between the illness and eating a number of food items from two restaurants however, environmental investigation of the two venues did not identify a definitive source for the outbreak. This investigation demonstrates the usefulness of email in the distribution of questionnaires among specific cohorts.

Enhancing foodborne disease surveillance across Australia in 2001: the OzFoodNet Working Group.

In 2000, the OzFoodNet network was established to enhance surveillance of foodborne diseases across Australia. OzFoodNet consists of 7 sites and covers 68 per cent of Australia's population. During 2001, sites reported 15,815 cases of campylobacteriosis, 6,607 cases of salmonellosis, 326 cases of shigellosis, 71 cases of yersiniosis, 61 cases of listeriosis, 47 cases of shiga-toxin producing E. coli and 5 cases of haemolytic uraemic syndrome. Sites reported 86 foodborne outbreaks affecting 1,768 people, of whom 4.0 per cent (70/1,768) were hospitalised and one person died. There was a wide range of foods implicated in these outbreaks and the most common agent was S. Typhimurium. Sites reported two international outbreaks; one of multi-drug resistant S. Typhimurium Definitive Type 104 due to helva imported from Turkey, and one of S. Stanley associated with dried peanuts from China. The National Centre for Epidemiology and Population Health conducted a national survey of gastroenteritis. Preliminary data from interviews of 2,417 people suggests that the incidence of foodborne illness is significantly higher than previously thought. OzFoodNet initiated case control studies into risk factors for Campylobacter, Salmonella, Listeria, and shiga-toxin producing E. coli. OzFoodNet developed a foodborne disease outbreak register for Australia; established a network of laboratories to type Campylobacter; prepared a survey of pathology laboratories; reviewed Australian data on listeriosis; and assessed the usefulness of sentinel surveillance for gastroenteritis. This program of enhanced surveillance has demonstrated its capacity to nationally investigate and determine the causes of foodborne disease.