Source attribution of campylobacteriosis in Australia, 2017-2019.

Campylobacter jejuni and Campylobacter coli infections are the leading cause of foodborne gastroenteritis in high-income countries. Campylobacter colonizes a variety of warm-blooded hosts that are reservoirs for human campylobacteriosis. The proportions of Australian cases attributable to different animal reservoirs are unknown but can be estimated by comparing the frequency of different sequence types in cases and reservoirs. Campylobacter isolates were obtained from notified human cases and raw meat and offal from the major livestock in Australia between 2017 and 2019. Isolates were typed using multi-locus sequence genotyping. We used Bayesian source attribution models including the asymmetric island model, the modified Hald model, and their generalizations. Some models included an "unsampled" source to estimate the proportion of cases attributable to wild, feral, or domestic animal reservoirs not sampled in our study. Model fits were compared using the Watanabe-Akaike information criterion. We included 612 food and 710 human case isolates. The best fitting models attributed >80% of Campylobacter cases to chickens, with a greater proportion of C. coli (>84%) than C. jejuni (>77%). The best fitting model that included an unsampled source attributed 14% (95% credible interval [CrI]: 0.3%-32%) to the unsampled source and only 2% to ruminants (95% CrI: 0.3%-12%) and 2% to pigs (95% CrI: 0.2%-11%) The best fitting model that did not include an unsampled source attributed 12% to ruminants (95% CrI: 1.3%-33%) and 6% to pigs (95% CrI: 1.1%-19%). Chickens were the leading source of human Campylobacter infections in Australia in 2017-2019 and should remain the focus of interventions to reduce burden.

Multistate Outbreak of Salmonella enterica Serovar Heidelberg with Unidentified Source, Australia, 2018-2019.

We report a multistate Salmonella enterica serovar Heidelberg outbreak in Australia during 2018-2019. Laboratory investigation of cases reported across 5 jurisdictions over a 7-month period could not identify a source of infection but detected indicators of severity and invasiveness. The hospitalization rate of 36% suggested a moderately severe clinical picture.

Risk factors for campylobacteriosis in Australia: outcomes of a 2018-2019 case-control study.

BACKGROUND: We aimed to identify risk factors for sporadic campylobacteriosis in Australia, and to compare these for Campylobacter jejuni and Campylobacter coli infections. METHODS: In a multi-jurisdictional case-control study, we recruited culture-confirmed cases of campylobacteriosis reported to state and territory health departments from February 2018 through October 2019. We recruited controls from notified influenza cases in the previous 12 months that were frequency matched to cases by age group, sex, and location. Campylobacter isolates were confirmed to species level by public health laboratories using molecular methods. We conducted backward stepwise multivariable logistic regression to identify significant risk factors. RESULTS: We recruited 571 cases of campylobacteriosis (422 C. jejuni and 84 C. coli) and 586 controls. Important risk factors for campylobacteriosis included eating undercooked chicken (adjusted odds ratio [aOR] 70, 95% CI 13-1296) or cooked chicken (aOR 1.7, 95% CI 1.1-2.8), owning a pet dog aged < 6 months (aOR 6.4, 95% CI 3.4-12), and the regular use of proton-pump inhibitors in the 4 weeks prior to illness (aOR 2.8, 95% CI 1.9-4.3). Risk factors remained similar when analysed specifically for C. jejuni infection. Unique risks for C. coli infection included eating chicken pâté (aOR 6.1, 95% CI 1.5-25) and delicatessen meats (aOR 1.8, 95% CI 1.0-3.3). Eating any chicken carried a high population attributable fraction for campylobacteriosis of 42% (95% CI 13-68), while the attributable fraction for proton-pump inhibitors was 13% (95% CI 8.3-18) and owning a pet dog aged < 6 months was 9.6% (95% CI 6.5-13). The population attributable fractions for these variables were similar when analysed by campylobacter species. Eating delicatessen meats was attributed to 31% (95% CI 0.0-54) of cases for C. coli and eating chicken pâté was attributed to 6.0% (95% CI 0.0-11). CONCLUSIONS: The main risk factor for campylobacteriosis in Australia is consumption of chicken meat. However, contact with young pet dogs may also be an important source of infection. Proton-pump inhibitors are likely to increase vulnerability to infection.

Characteristics of Campylobacter Gastroenteritis Outbreaks in Australia, 2001 to 2016.

Campylobacter spp. are a globally important cause of bacterial gastroenteritis, with Australia experiencing higher rates of illness than many comparable high-income countries. Despite the high disease incidence, outbreaks of campylobacteriosis in Australia are infrequently detected and reported. We examined the epidemiology of Campylobacter outbreaks in Australia, with particular emphasis on assessing transmission routes and evidence as reported during public health investigations. A national register of enteric and foodborne disease outbreaks was used to summarize data on all Campylobacter outbreaks reported in Australia between 2001 and 2016. Outbreak data were reviewed and analyzed for trends over time. Additional information was sought from state and territory epidemiologists, to validate transmission routes. A total of 84 Campylobacter outbreaks were reported, with 51 (61%) being classified as foodborne. Specific food vehicles were identified for 33 (65%) outbreaks, with 28 (85%) implicating chicken or chicken-containing dishes. Although no increase in the proportion of foodborne Campylobacter outbreaks was observed, examination of specific food vehicles demonstrated a significant increase in outbreaks because of poultry-liver containing foods (p = 0.04). One quarter of all 1042 outbreak-associated cases occurred in aged-care facilities (ACFs), including 17 associated hospitalizations and three deaths. After review of evidence data, 23 outbreaks (27%) were determined to have an unknown route of transmission, including 10 (43%) outbreaks occurring in ACFs. Campylobacter spp. remain a less commonly reported cause of gastroenteritis outbreaks in Australia. Although many reported outbreaks can be linked to foodborne transmission, over a quarter were unable to identify either a food vehicle or transmission source, particularly for outbreaks occurring in aged care. Increased efforts to improve evidence collection and understanding of transmission dynamics for outbreaks of campylobacteriosis, particularly in aged care, are required.

Waterparks are high risk for cryptosporidiosis: A case-control study in Victoria, 2015.

BACKGROUND: An increase in notifications of cryptosporidiosis was observed in Victoria between March and April 2015. Cases mostly resided in one metropolitan region and hypothesis-generating interviews identified common exposures to aquatic facilities. We conducted a case-control study to determine exposure source(s) and facilitate control measures. METHODS: Laboratory-confirmed cases of cryptosporidiosis from the region of interest notified between 1 March and 23 April 2015 were included. Controls residing in the same region were recruited from participants in a population health survey and frequency matched (2 per case) by age group. Details of exposure to potential risk factors were collected using a standardised telephone questionnaire for the 14-days prior to illness for cases, and an analogous exposure period for controls. Univariable and multivariable logistic regression were used to determine risk factors associated with illness using STATA SE 13.1. RESULTS: Thirty cases and 66 controls were included in the study. Half the cases were less than 12 years of age and 62% were female. Illness was most strongly associated with recreational water exposure at any waterpark (adjusted odds ratio (aOR)=73.5; 95% confidence interval (CI):6.74-802), and specifically at Victorian waterparks (aOR=45.6; 95% CI:5.20-399). Cases were linked with attendance at either a waterpark in the region or an adjacent region. As a result of this investigation, hyperchlorination was completed at identified facilities and swim hygiene information distributed. CONCLUSION: This study reinforces the potential for recreational water facilities, particularly waterparks, to act as a transmission source of Cryptosporidium infections. Continued communication to patrons is required to ensure healthy swimming practice in Victorian aquatic facilities.

The effects of culture independent diagnostic testing on the diagnosis and reporting of enteric bacterial pathogens in Queensland, 2010 to 2014.

Changes in diagnostic laboratory testing procedures can impact on the number of cases notified and the public health surveillance of enteric pathogens. Culture independent diagnostic testing using a multiplex polymerase chain reaction (PCR) test was introduced for the rapid detection of bacterial enteric pathogens in pathology laboratories in Queensland, Australia, from late 2013 onwards. We conducted a retrospective descriptive study using laboratory data to assess the impact of the introduction of PCR testing on four common enteric pathogens, Salmonella, Campylobacter, Shigella and Yersinia, in Queensland between 2010 and 2014. The number of stool specimens tested and the proportion positive for each of the four pathogens increased in 2014 after the introduction of culture independent diagnostic testing. Among the specimens tested by both PCR and culture, 12% of Salmonella positive stools, 36% of Campylobacter positive stools, 74% of Shigella / enteroinvasive Escherichia coli positive stools and 65% of Yersinia positive stools were PCR positive only. Including those where culture was not performed, 19% of Salmonella positive stools, 44% of Campylobacter positive stools, 83% of Shigella positive stools and 79% of Yersinia positive stools had no cultured isolate available for further characterisation. The detection and tracking of foodborne and non-foodborne gastrointestinal outbreaks will become more difficult as culture independent diagnostic testing becomes more widespread. Until new techniques for characterisation of pathogens directly from clinical specimens have been developed, we recommend laboratories continue to culture specimens concurrently or reflexively with culture independent diagnostic tests.

Epidemiology of bacterial toxin-mediated foodborne gastroenteritis outbreaks in Australia, 2001 to 2013.

Bacterial toxin-mediated foodborne outbreaks, such as those caused by Clostridium perfringens, Staphylococcus aureus and Bacillus cereus, are an important and preventable cause of morbidity and mortality. Due to the short incubation period and duration of illness, these outbreaks are often under-reported. This is the first study to describe the epidemiology of bacterial toxin-mediated outbreaks in Australia. Using data collected between 2001 and 2013, we identify high risk groups and risk factors to inform prevention measures. Descriptive analyses of confirmed bacterial toxin-mediated outbreaks between 2001 and 2013 were undertaken using data extracted from the OzFoodNet Outbreak Register, a database of all outbreaks of gastrointestinal disease investigated by public health authorities in Australia. A total of 107 laboratory confirmed bacterial toxin-mediated outbreaks were reported between 2001 and 2013, affecting 2,219 people, including 47 hospitalisations and 13 deaths. Twelve deaths occurred in residents of aged care facilities. Clostridium perfringens was the most commonly reported aetiological agent (81 outbreaks, 76%). The most commonly reported food preparation settings were commercial food preparation services (51 outbreaks, 48%) and aged care facilities (42 outbreaks, 39%). Bacterial toxin outbreaks were rarely associated with food preparation in the home (2 outbreaks, 2%). In all outbreaks, the primary factor contributing to the outbreak was inadequate temperature control of the food. Public health efforts aimed at improving storage and handling practices for pre-cooked and re-heated foods, especially in commercial food preparation services and aged care facilities, could help to reduce the magnitude of bacterial toxin outbreaks.

The Australian Master of Applied Epidemiology Program: Looking back, moving forward.

The Master of Applied Epidemiology Program is Australia's Field Epidemiology Training Program. It was established in 1991 and was run out of the National Centre for Population Health (NCEPH) at the Australian National University. The Program has a strong track record in using field-based training to produce competent applied epidemiologists who have contributed to public health in Australia and globally. A new funding model for the program was implemented in 2012, backed by funds from field placement partners and NCEPH. In this paper we review the program's origins and achievements, discuss the ongoing needs of the program and outline a vision for the future. Commun Dis Intell 2016;40(3):E326-E333.

Approaches to the Surveillance of Foodborne Disease: A Review of the Evidence.

Foodborne disease surveillance aims to reduce the burden of illness due to contaminated food. There are several different types of surveillance systems, including event-based surveillance, indicator-based surveillance, and integrated food chain surveillance. These approaches are not mutually exclusive, have overlapping data sources, require distinct capacities and resources, and can be considered a hierarchy, with each level being more complex and resulting in a greater ability to detect and control foodborne disease. Event-based surveillance is generally the least resource-intensive system and makes use of informal data sources. Indicator-based surveillance is seen as traditional notifiable disease surveillance and consists of routinely collected data. Integrated food chain surveillance is viewed as the optimal practice for conducting continuous risk analysis for foodborne diseases, but also requires significant ongoing resources and greater multisectoral collaboration compared to the other systems. Each country must determine the most appropriate structure for their surveillance system for foodborne diseases based on their available resources. This review explores the evidence on the principles, minimum capabilities, and minimum requirements of each type of surveillance and discusses examples from a range of countries. This review forms the evidence base for the Strengthening the Surveillance and Response for Foodborne Diseases: A Practical Manual.

Monitoring the incidence and causes of disease potentially transmitted by food in Australia: Annual report of the OzFoodNet network, 2016.

ABSTRACT: In 2016, a total of 44,455 notifications of enteric diseases potentially related to food were received by state and territory health departments in Australia. Consistent with previous years, campylobacteriosis (n = 24,171) and salmonellosis (n = 18,060) were the most frequently-notified infections. Notable increases in incidence were observed for shiga toxin-producing Escherichia coli (n = 343; 166% increase), shigellosis (n = 1,408; 93% increase), campylobacteriosis (33% increase) and salmonellosis (30% increase) when compared with the historical five-year mean. The extent to which the introduction of culture-independent testing as a method of diagnosis has contributed to these increases remains unclear. In total, 188 gastrointestinal outbreaks, including 177 foodborne outbreaks, were reported in 2016. The 11 non-foodborne outbreaks were due to environmental or probable environmental transmission (nine outbreaks) and animal-to-person or probable animal-to-person transmission (two outbreaks). No outbreaks of waterborne or probable waterborne transmission were reported in 2016. Foodborne outbreaks affected 3,639 people, resulting in at least 348 hospital admissions and four deaths. Eggs continue to be a source of Salmonella Typhimurium infection across the country: 35 egg-related outbreaks, affecting approximately 510 people, were reported across six jurisdictions in 2016. Three large multi-jurisdictional Salmonella outbreaks associated with mung bean sprouts (n = 419 cases); bagged salad products (n = 311 cases); and rockmelons (n = 144 cases) were investigated in 2016. These outbreaks highlight the risks associated with fresh raw produce and the ongoing need for producers, retailers and consumers to implement strategies to reduce potential Salmonella contamination.

Polycystic ovary syndrome increases the risk of endometrial cancer in women aged less than 50 years: an Australian case-control study.

OBJECTIVE: Although polycystic ovary syndrome (PCOS) is commonly cited as a risk factor for endometrial cancer, supporting epidemiological evidence is currently very limited. Our aim was to assess the associations between PCOS, PCOS symptoms, and risk of endometrial cancer in women aged less than 50 years. METHODS: Data came from a national population-based case-control study in Australia. Cases with newly diagnosed histologically confirmed endometrial cancer were identified through treatment clinics and cancer registries Australia wide. Controls were randomly selected from the national electoral roll. Women were interviewed about their reproductive and medical history, including self-reported PCOS, and lifestyle. Current analyses were restricted to women aged under 50 (156 cases, 398 controls). We estimated odds ratios (OR) using logistic regression to adjust for confounding factors. RESULTS: Women with PCOS had a fourfold increased risk of endometrial cancer compared to women without PCOS (OR 4.0, 95% CI 1.7-9.3). This association was attenuated when additionally adjusted for body mass index (OR 2.2, 95% CI 0.9-5.7). Risk was slightly greater when restricted to Type I cancers. PCOS symptoms including hirsutism and very irregular periods were significantly associated with endometrial cancer risk. CONCLUSIONS: These data extend existing findings, including adjustment for confounders, suggesting PCOS is a risk factor for endometrial cancer.

Local weather, flooding history and childhood diarrhoea caused by the parasite Cryptosporidium spp.: A systematic review and meta-analysis.

Scientists have long predicted the impacts of climate-related infectious disease emergence. Yet, the combined effect of local socioeconomic and demographic factors and weather variation on child health is poorly understood. With a focus on childhood diarrhoea caused by the parasite Cryptosporidium spp., - an infection easily controlled by public health interventions but also strongly linked to environmental conditions through waterborne spread, we systematically review and empirically model the effects of local weather and flooding history, after controlling for seasonality, publication bias, access to improved sanitation, health resources and population density at a global scale. We examined 1588 papers on childhood cryptosporidiosis and identified 36 studies representing a range of geographic locations and climatic, environmental and socio-economic conditions. Local rainfall and population density were related with cryptosporidiosis across latitudes as shown by mixed effects, spatio-temporal models for equatorial, sub-tropical and temperate climates. In equatorial (0-20°) latitudes, the previous month's rainfall and population density were inversely related with childhood cryptosporidiosis with a significant random effect for flooding history. In tropical-subtropical (20-35°) latitudes, rainfall in December was inversely related with cryptosporidiosis, compared to rainfall in April (the wet season). In temperate latitudes (>35°), there was a significant negative association of reported disease with population density. This global empirical analysis indicates differential spatio-temporal patterns of childhood cryptosporidiosis in low, mid and high latitude regions. Models that couple weather conditions with demographic factors are needed to assess disease distributional shifts and risks due to environmental change. These results may provide impetus to develop environment-focused public health policies to manage disease risks associated with climate change for future generations.

Impact of the national targeted Hepatitis A immunisation program in Australia: 2000-2014.

In November 2005, hepatitis A vaccine was funded under the Australian National Immunisation Program for Aboriginal and Torres Strait Islander (Indigenous) children aged 12-24months in the targeted jurisdictions of Queensland, South Australia, Western Australia and the Northern Territory. We reviewed the epidemiology of hepatitis A from 2000 to 2014 using data from the Australian National Notifiable Diseases Surveillance System, the National Hospital Morbidity Database, and Australian Bureau of Statistics causes-of-death data. The impact of the national hepatitis A immunisation program was assessed by comparison of pre-vaccine (2000-2005) and post-vaccine time periods (2006-2014), by age group, Indigenous status and jurisdiction using incidence rate ratios (IRR) per 100,000 population and 95% confidence intervals (CI). The national pre-vaccine notification rate in Indigenous people was four times higher than the non-Indigenous rate, and declined from 8.41 per 100,000 (95% CI 5.03-11.79) pre-vaccine to 0.85 per 100,000 (95% CI 0.00-1.99) post-vaccine, becoming similar to the non-Indigenous rate. Notification and hospitalisation rates in Indigenous children aged <5years from targeted jurisdictions declined in the post-vaccine period when compared to the pre-vaccine period (notifications: IRR=0.07; 95% CI 0.04-0.13; hospitalisations: IRR=0.04; 95% CI 0.01-0.16). As did notification rates in Indigenous people aged 5-19 (IRR=0.08; 95% CI 0.05-0.13) and 20-49years (IRR=0.06; 95% CI 0.02-0.15) in targeted jurisdictions. For non-Indigenous people from targeted jurisdictions, notification rates decreased significantly in children aged <5years (IRR 0.47; 95% CI 0.31-0.71), and significantly more overall (IRR=0.43; 95% CI 0.39-0.47) compared to non-Indigenous people from non-targeted jurisdictions (IRR=0.60; 95% CI 0.56-0.64). The national hepatitis A immunisation program has had a significant impact in the targeted population with relatively modest vaccine coverage, with evidence suggestive of substantial herd protection effects.

The Risk of Reported Cryptosporidiosis in Children Aged <5 Years in Australia is Highest in Very Remote Regions.

The incidence of cryptosporidiosis is highest in children <5 years, yet little is known about disease patterns across urban and rural areas of Australia. In this study, we examine whether the risk of reported cryptosporidiosis in children <5 years varies across an urban-rural gradient, after controlling for season and gender. Using Australian data on reported cryptosporidiosis from 2001 to 2012, we spatially linked disease data to an index of geographic remoteness to examine the geographic variation in cryptosporidiosis risk using negative binomial regression. The Incidence Risk Ratio (IRR) of reported cryptosporidiosis was higher in inner regional (IRR 1.4 95% CI 1.2-1.7, p < 0.001), and outer regional areas (IRR 2.4 95% CI 2.2-2.9, p < 0.001), and in remote (IRR 5.2 95% CI 4.3-6.2, p < 0.001) and very remote (IRR 8.2 95% CI 6.9-9.8, p < 0.001) areas, compared to major cities. A linear test for trend showed a statistically significant trend with increasing remoteness. Remote communities need to be a priority for future targeted health promotion and disease prevention interventions to reduce cryptosporidiosis in children <5 years.

Cryptosporidiosis: A Disease of Tropical and Remote Areas in Australia.

Cryptosporidiosis causes gastroenteritis and is transmitted to humans via contaminated water and food, and contact with infected animals and people. We analyse long-term cryptosporidiosis patterns across Australia (2001-2012) and review published Australian studies and jurisdictional health bulletins to identify high risk populations and potential risk factors for disease. Using national data on reported cryptosporidiosis, the average annual rate of reported illness was 12.8 cases per 100 000 population, with cycles of high and low reporting years. Reports of illness peak in summer, similar to other infectious gastrointestinal diseases. States with high livestock densities like New South Wales and Queensland also record a spring peak in illnesses. Children aged less than four years have the highest rates of disease, along with adult females. Rates of reported cryptosporidiosis are highest in the warmer, remote regions and in Aboriginal and Torres Strait Islander populations. Our review of 34 published studies and seven health department reports on cryptosporidiosis in Australia highlights a lack of long term, non-outbreak studies in these regions and populations, with an emphasis on outbreaks and risk factors in urban areas. The high disease rates in remote, tropical and subtropical areas and in Aboriginal and Torres Strait Islander populations underscore the need to develop interventions that target the sources of infection, seasonal exposures and risk factors for cryptosporidiosis in these settings. Spatial epidemiology can provide an evidence base to identify priorities for intervention to prevent and control cryptosporidiosis in high risk populations.

Environmental correlates of mental health measures for women in Western Australia.

A recent study in Western Australia identified area level associations between soil salinisation and hospital admissions for depression. Our study assessed the quantitative relationship between mental health measures at the individual level and location specific environmental measurements on salinity, as well as two other indicators of environmental degradation and change: land surface temperature and normalised difference vegetation index, a proxy for rainfall. Location-specific environmental measurements were linked to individual mental health scores of women in three age cohorts from the Australian Longitudinal Study on Women's Health using a geographic information system. Bayesian geostatistical linear regression models were developed to assess associations between environmental exposures and mental health scores of women. In contrast to previous studies using area level measures, our study found no associations between individual level measurements of mental health scores for women in south-west Western Australia and salinity, LST or NDVI.

'Surprise': Outbreak of Campylobacter infection associated with chicken liver pâté at a surprise birthday party, Adelaide, Australia, 2012.

OBJECTIVE: In July 2012, an outbreak of Campylobacter infection was investigated by the South Australian Communicable Disease Control Branch and Food Policy and Programs Branch. The initial notification identified illness at a surprise birthday party held at a restaurant on 14 July 2012. The objective of the investigation was to identify the potential source of infection and institute appropriate intervention strategies to prevent further illness. METHODS: A guest list was obtained and a retrospective cohort study undertaken. A combination of paper-based and telephone questionnaires were used to collect exposure and outcome information. An environmental investigation was conducted by Food Policy and Programs Branch at the implicated premises. RESULTS: All 57 guests completed the questionnaire (100% response rate), and 15 met the case definition. Analysis showed a significant association between illness and consumption of chicken liver pâté (relative risk: 16.7, 95% confidence interval: 2.4-118.6). No other food or beverage served at the party was associated with illness. Three guests submitted stool samples; all were positive for Campylobacter. The environmental investigation identified that the cooking process used in the preparation of chicken liver pâté may have been inconsistent, resulting in some portions not cooked adequately to inactivate potential Campylobacter contamination. DISCUSSION: Chicken liver products are a known source of Campylobacter infection; therefore, education of food handlers remains a high priority. To better identify outbreaks among the large number of Campylobacter notifications, routine typing of Campylobacter isolates is recommended.

Leptospirosis in American Samoa 2010: epidemiology, environmental drivers, and the management of emergence.

Leptospirosis has recently been reported as an emerging disease worldwide, and a seroprevalence study was undertaken in American Samoa to better understand the drivers of transmission. Antibodies indicative of previous exposure to leptospirosis were found in 15.5% of 807 participants, predominantly against three serovars that were not previously known to occur in American Samoa. Questionnaires and geographic information systems data were used to assess behavioral factors and environmental determinants of disease transmission, and logistic regression was used to identify factors associated with infection. Many statistically significant factors were consistent with previous studies, but we also showed a significant association with living at lower altitudes (odds ratio [OR] = 1.53, 95% confidence interval [CI]: 1.03-2.28), and having higher numbers of piggeries around the home (OR = 2.63, 95% CI: 1.52-4.40). Our findings support a multifaceted approach to combating the emergence of leptospirosis, including modification of individual behavior, but importantly also managing the evolving environmental drivers of risk.

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.

Biodiversity and leptospirosis risk: a case of pathogen regulation?

Well balanced ecosystems have an essential role in disease regulation, and consequently their correct functioning is increasingly recognised as imperative for maintaining human health. Disruptions to ecosystems have been found to increase the risk of several diseases, including Hantavirus, Lyme disease, Ross River virus, malaria and Ciguatera fish poisoning. Leptospirosis is a globally important emerging zoonosis, caused by spirochaete bacteria, borne by many mammalian hosts, and also transmitted environmentally. We propose that leptospirosis incidence in humans is also linked to ecosystem disruption, and that reduced biodiversity (the diversity of species within an ecological community) may be associated with increased leptospirosis incidence. To investigate this hypothesis, the relationship between biodiversity levels of island nations and their annual leptospirosis incidence rates (adjusted for GDP per capita) was examined by linear correlation and regression. Supportive, statistically significant negative associations were obtained between leptospirosis incidence and (a) total number of species (r2=0.69, p<0.001) and (b) number of mammal species (r2=0.80, p<0.001) in univariate analysis. In multivariable analysis only the number of mammal species remained significantly associated (r2=0.81, p=0.007). An association between biodiversity and reduced leptospirosis risk, if supported by further research, would emphasise the importance of managing the emergence of leptospirosis (and other infectious diseases) at a broader, ecosystem level.