Mark Veitch

Case-control studies of sporadic cryptosporidiosis in Melbourne and Adelaide, Australia.

Few studies have assessed risk factors for sporadic cryptosporidiosis in industrialized countries, even though it may be numerically more common than outbreaks of disease. We carried out case-control studies assessing risk factors for sporadic disease in Melbourne and Adelaide, which have water supplies from different ends of the raw water spectrum. In addition to examining drinking water, we assessed several other exposures. 201 cases and 795 controls were recruited for Melbourne and 134 cases and 536 controls were recruited for Adelaide. Risk factors were similar for the two cities, with swimming in public pools and contact with a person with diarrhoea being most important. The consumption of plain tap water was not found to be associated with disease. This study emphasizes the need for regular public health messages to the public and swimming pool managers in an attempt to prevent sporadic cryptosporidiosis, as well as outbreaks of disease.

Gastroenteritis and Food-Borne Disease in Elderly People Living in Long-Term Care

Elderly people in long-term care facilities (LTCFs) may be more vulnerable to infectious gastroenteritis and food-borne disease and more likely to experience serious outcomes. We review the epidemiology of gastroenteritis and food-borne diseases in elderly residents of LTCFs to inform measures aimed at preventing sporadic disease and outbreaks. Gastroenteritis in elderly people is primarily acquired from other infected persons and contaminated foods, although infections may also be acquired when residents have poor personal hygiene, have contaminated living environments or water, or have contact with infected pets. Early recognition of outbreaks and implementation of control measures is critical to reduce the effects on LTCF residents and staff members. Although outbreaks among LTCF residents are common, they are challenging to investigate, and there are still major gaps in our knowledge, particularly in regards to controlling noroviruses, the incidence and causes of specific infections, and sources of food-borne disease.

Surveillance for outbreaks of gastroenteritis in long-term care facilities, Australia, 2002-2008.

BACKGROUND Each year in Australia, health departments investigate hundreds of gastroenteritis outbreaks. Long-term care facilities (LTCFs) for elderly persons are a common setting for these outbreaks and can result in potentially serious outcomes. METHODS We established surveillance for gastroenteritis outbreaks in 2001, and analyzed data on outbreaks occurring from 1 July 2002 through 30 June 2008 to estimate the incidence in Australian LTCFs and residents. We summarized outbreaks by mode of transmission and etiological agent. We used negative binomial regression to examine variation in the number of fecal specimens collected in outbreaks-a marker of investigation intensity. RESULTS During surveillance, 3257 (52%) of 6295 outbreaks of gastroenteritis and foodborne disease in Australia were reported in LTCFs. These outbreaks affected 84,769 people, with 1577 people hospitalized and 209 deaths. There were 0.19 (95% confidence interval, 0.14-0.26) residents affected per 1000 bed days and 16.8 (95% confidence interval, 12.4-22.7) outbreaks per 100 LTCFs annually. LTCF outbreaks were most commonly transmitted from person to person. Only 43 (1.3% ) of 3257 outbreaks were foodborne, although 47 (6.4%) of 733 residents were hospitalized and 20 (2.7%) of 733 died. Norovirus was responsible for 1136 (35%) of all 3257 outbreaks. Higher numbers of fecal specimens per outbreak were collected in 4 Australian States, in later years of surveillance, and where the etiology was identified. CONCLUSIONS Norovirus outbreaks spread from person to person are common in LTCFs, although clinicians should be alert for foodborne outbreaks with more serious consequences. There is a need to identify effective infection control measures to assist facilities in managing outbreaks of gastroenteritis.

Case-control Studies of Sporadic Cryptosporidiosis in Melbourne and Adelaide

Publisher Summary Outbreaks of cryptosporidiosis have been attributed to contaminated drinking water, recreational water, person-to-person transmission, and some food materials. The number of cryptosporidiosis cases associated with recognized outbreaks probably represents only a small fraction of all cases occurring in a community over time. Thus the disease burden and related public health costs of sporadic cryptosporidiosis may be more significant than for outbreaks. The primary focus of international research to date has been the cause of outbreaks of cryptosporidiosis though it is also vital to identify the risk factors for sporadic disease to develop appropriate public health responses for reducing disease rates. This chapter presents a set of case-control studies conducted between 1998 and 2001 to assess risk factors for sporadic cryptosporidiosis in Melbourne and Adelaide. The studies carefully assessed drinking water because of the potential importance of population exposure via this route.

Proportion of Illness Acquired by Foodborne Transmission for Nine Enteric Pathogens in Australia: An Expert Elicitation

BACKGROUND Estimates of the burden of illness acquired from food inform public health policy and prioritize interventions. A key component of such estimates is the proportion of illnesses that are acquired by foodborne transmission. In view of the shortage of requisite data, these proportions are commonly obtained through a process known as expert elicitation. We report findings from an elicitation process used to assess the importance of the foodborne transmission route for nine pathogens in Australia, circa 2010. MATERIALS AND METHODS Eleven experts were asked to estimate the proportion of illness acquired by five transmission routes: food, environmental, water, person, and zoonotic, together with a 90% certainty interval for foodborne transmission. Foodborne estimates and intervals from each expert were combined using both modified triangular and Program Evaluation and Review Technique (PERT) distributions, in @Risk version 6, to generate final distributions from which median estimates and 95% Credible Intervals (CrI) were calculated. RESULTS Shiga toxin-producing Escherichia coli (STEC) was the only pathogen believed to have an important zoonotic transmission route, while norovirus, hepatitis A virus, non-STEC pathogenic E. coli, and Shigella spp. were all thought to be primarily spread from person to person. Foodborne transmission was the main route for Clostridium perfringens (98%, CrI: 84-100), Listeria monocytogenes (98%, CrI: 86-100), nontyphoidal Salmonella spp. (72%, CrI: 50-87), and Campylobacter spp. (77%, CrI: 60-90). Foodborne estimates using the modified triangular distribution had wider CrI than these calculated using the PERT distribution. CONCLUSIONS Foodborne proportions for most pathogens in this study were the same or lower than those estimated circa 2000 in Australia, with the greatest decline for non-STEC pathogenic E. coli. Inclusion of certainty intervals from experts helps to quantify the precision of foodborne proportions. A decline in estimates of the foodborne proportion for common pathogens will influence final estimates of the burden of illness acquired from food.

Bayesian Source Attribution of Salmonellosis in South Australia.

Salmonellosis is a significant cause of foodborne gastroenteritis in Australia, and rates of illness have increased over recent years. We adopt a Bayesian source attribution model to estimate the contribution of different animal reservoirs to illness due to Salmonella spp. in South Australia between 2000 and 2010, together with 95% credible intervals (CrI). We excluded known travel associated cases and those of rare subtypes (fewer than 20 human cases or fewer than 10 isolates from included sources over the 11-year period), and the remaining 76% of cases were classified as sporadic or outbreak associated. Source-related parameters were included to allow for different handling and consumption practices. We attributed 35% (95% CrI: 20-49) of sporadic cases to chicken meat and 37% (95% CrI: 23-53) of sporadic cases to eggs. Of outbreak-related cases, 33% (95% CrI: 20-62) were attributed to chicken meat and 59% (95% CrI: 29-75) to eggs. A comparison of alternative model assumptions indicated that biases due to possible clustering of samples from sources had relatively minor effects on these estimates. Analysis of source-related parameters showed higher risk of illness from contaminated eggs than from contaminated chicken meat, suggesting that consumption and handling practices potentially play a bigger role in illness due to eggs, considering low Salmonella prevalence on eggs. Our results strengthen the evidence that eggs and chicken meat are important vehicles for salmonellosis in South Australia.

How well does a telephone questionnaire measure drinking water intake

Background:Few studies have assessed the validity or reliability of drinking water intake estimations. In studies investigating potential waterborne disease, this is very important.

Increasing Incidence of Salmonella in Australia, 2000-2013

Salmonella is a key cause of foodborne gastroenteritis in Australia and case numbers are increasing. We used negative binomial regression to analyze national surveillance data for 2000–2013, for Salmonella Typhimurium and non-Typhimurium Salmonella serovars. We estimated incidence rate ratios adjusted for sex and age to show trends over time. Almost all states and territories had significantly increasing trends of reported infection for S. Typhimurium, with states and territories reporting annual increases as high as 12% (95% confidence interval 10–14%) for S. Typhimurium in the Australian Capital Territory and 6% (95% CI 5–7%) for non-Typhimurium Salmonella in Victoria. S. Typhimurium notification rates were higher than non-Typhimurium Salmonella rates in most age groups in the south eastern states of Australia, while non-Typhimurium rates were higher in most age groups elsewhere. The S. Typhimurium notification rate peaked at 12–23 months of age and the non-Typhimurium Salmonella notification rate peaked at 0–11 months of age. The age-specific pattern of S. Typhimurium cases suggests a foodborne origin, while the age and geographic pattern for non-Typhimurium may indicate that other transmission routes play a key role for these serovars.

Increasing antimicrobial resistance in non-typhoidal Salmonella in Australia, 1979 - 2015

ABSTRACT Australia has high and increasing rates of salmonellosis. To date, the serovar distribution and associated antimicrobial resistance (AMR) patterns of nontyphoidal Salmonella enterica (NTS) in Australia have not been assessed. Such information provides critical knowledge about AMR in the food chain and informs decisions about public health. We reviewed longitudinal data on NTS in two Australian states over a 37-year period, between 1979 and 2015, and antimicrobial resistance since 1984. Overall, 17% of isolates were nonsusceptible to at least one antimicrobial, 4.9% were nonsusceptible to ciprofloxacin, and 0.6% were nonsusceptible to cefotaxime. In total, 2.5% of isolates were from invasive infections, with no significant difference in AMR profiles between invasive and noninvasive isolates. Most isolates with clinically relevant AMR profiles were associated with travel, particularly to Southeast Asia, with multiple “incursions” of virulent and resistant clones into Australia. Our findings represent the largest longitudinal surveillance system for NTS in Australia and provide valuable public health knowledge on the trends and distribution of AMR in NTS. Ongoing surveillance is critical to identify local emergence of resistant isolates.

Must it have been something I ate

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