Jane Raupach

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

BackgroundShiga 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.MethodsNational and state notifications data, as well as data on serotypes, hospitalizations, mortality and outbreaks were examined.ResultsFor 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.ConclusionsSTEC 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.

Estimating Community Incidence of Salmonella, Campylobacter, and Shiga Toxin-producing Escherichia coli Infections, Australia

Estimated multipliers that linked surveillance of foodborne diseases with community incidence showed a high prevalence of these diseases.

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.

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.

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.

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

Bayesian Source Attribution of Salmonellosis in South Australia.

144,087, equating to a mean cost of AUD

MLVA and Phage Typing as Complementary Tools in the Epidemiological Investigation of Salmonella enterica serovar Typhimurium Clusters

3132 per case. We estimate that the annual total costs of STEC infection in South Australia and Australia are AUD

Food- and Waterborne Disease Outbreaks in Australian Long-Term Care Facilities, 2001–2008

200,283 and AUD

Reported foodborne illness and gastroenteritis in Australia: annual report of the OzfoodNet network, 2004.

2,633,181, respectively. We used linear regression to identify that STEC infection costs increase by AUD