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.

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.

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.

The immunogenicity of a modified intradermal pre-exposure rabies vaccination schedule--a case series of 420 travelers.

BACKGROUND: Current Australian recommendations for rabies pre-exposure vaccination involve the use of cell-culture-based rabies vaccines, which are administered via intramuscular (IM) or intradermal (ID) routes. ID vaccination is more affordable for travelers, but is only recommended if there is sufficient time to perform serology 2 to 3 weeks post-vaccination and confirm immunity prior to travel. We report the immunogenicity of a modified ID schedule that can be completed in less time than the standard ID schedule, and allow more travelers to be vaccinated prior to departure. METHODS: Travelers were offered a modified schedule if they were unable to afford standard IM vaccinations, and did not have time to complete a standard ID course. The modified schedule consisted of two ID injections of 0.1 mL of human diploid cell rabies vaccine administered on days 0 and 7, and serology was performed to determine immune status at a time between day 21 and 28. RESULTS: A total of 420 travelers aged between 10 and 65 years were vaccinated using the modified ID course. The overall seroconversion rate was 94.5%, with 397 travelers developing antibody levels of >0.5 IU/mL when tested at approximately 21 days post-vaccination. CONCLUSION: The modified ID schedule used in this case series was highly effective, had similar immunogenicity to the standard ID schedule, and should be considered in travelers who are unable to complete standard IM or standard ID courses of rabies vaccines.

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.

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.