Estimating the incidence of COVID-19, influenza and respiratory syncytial virus infection in three regions of Queensland, Australia, winter 2022: findings from a novel longitudinal testing-based sentinel surveillance programme.

OBJECTIVE: The 2022 Australian winter was the first time that COVID-19, influenza and respiratory syncytial virus (RSV) were circulating in the population together, after two winters of physical distancing, quarantine and borders closed to international travellers. We developed a novel surveillance system to estimate the incidence of COVID-19, influenza and RSV in three regions of Queensland, Australia. DESIGN: We implemented a longitudinal testing-based sentinel surveillance programme. Participants were provided with self-collection nasal swabs to be dropped off at a safe location at their workplace each week. Swabs were tested for SARS-CoV-2 by PCR. Symptomatic participants attended COVID-19 respiratory clinics to be tested by multiplex PCR for SARS-CoV-2, influenza A and B and RSV. Rapid antigen test (RAT) results reported by participants were included in the analysis. SETTING AND PARTICIPANTS: Between 4 April 2022 and 3 October 2022, 578 adults were recruited via their workplace. Due to rolling recruitment, withdrawals and completion due to positive COVID-19 results, the maximum number enrolled in any week was 423 people. RESULTS: A total of 4290 tests were included. Participation rates varied across the period ranging from 25.9% to 72.1% of enrolled participants. The total positivity of COVID-19 was 3.3%, with few influenza or RSV cases detected. Widespread use of RAT may have resulted in few symptomatic participants attending respiratory clinics. The weekly positivity rate of SARS-CoV-2 detected during the programme correlated with the incidence of notified cases in the corresponding communities. CONCLUSION: This testing-based surveillance programme could estimate disease trends and be a useful tool in settings where testing is less common or accessible. Difficulties with recruitment meant the study was underpowered. The frontline sentinel nature of workplaces meant participants were not representative of the general population but were high-risk groups providing early warning of disease.

Q fever infection is a preventable risk associated with pet food manufacturing.

OBJECTIVE: This paper highlights the occupational risk of Q fever from exposure to raw animal products in the context of multiple notified Q fever cases from 2020 to 2023 linked to four pet food manufacturing facilities in South-East Queensland, Australia. METHODS: The Queensland Government Notifiable Conditions System was used to identify Q fever cases linked to pet food manufacturing in the Metro North and Gold Coast Hospital and Health Service areas of Brisbane, Australia. Data on each case from routine public health follow-up were collected and descriptively analysed. RESULTS: Between 2020 and 2023, 12 confirmed Q fever infections (17% of total cases) were linked to four pet food manufacturing facilities. Eleven cases reported direct or environmental exposure to raw meat and animal products. None were previously vaccinated for Q fever. CONCLUSION: These cases demonstrate the increased risk of Q fever infection as part of the pet food manufacturing process, highlighting an underappreciated preventable occupational risk, which can be mitigated with the use of pre-screening and vaccination of workers. All occupations should conduct workplace-based risk assessments to identify risks such as Q fever to prevent adverse negative health outcomes.

Several confirmed and probable zoonotic cases of toxigenic Corynebacterium ulcerans, Queensland, Australia.

Background: Toxigenic Corynebacterium ulcerans is an emerging zoonosis globally, causing both cutaneous and respiratory diphtheria-like illness. In Queensland, human infection with toxigenic C. ulcerans is rare, with only three cases reported before October 2015. This case series describes five subsequent cases of toxigenic C. ulcerans in Queensland with links to companion animals. Methods: All data were collected as part of routine public health response, and strains were whole genome sequenced for further characterisation. Household contacts were screened, treated with appropriate antibiotics, and received a diphtheria toxoid-containing vaccine if more than five years had elapsed since their last dose. Findings: No epidemiological or genomic links could be established between any of the five patients, including between the two cases notified from the same locality within eight days of each other. The C. ulcerans strains from Cases Two, Four and Five were closely related to the strains isolated from their respective pets by whole genome sequencing. Domestic dogs were identified as the most likely mode of transmission for Cases One and Three; however, this was unable to be laboratory confirmed, since Case One's dog was treated with antibiotics before it could be tested, and Case Three's dog was euthanised and cremated prior to case notification. Interpretation: These are the first reported Australian cases of this emerging zoonosis with links to companion animals. These cases demonstrate the likely transmission route between companion animals and humans, with no evidence of human-to-human transmission. The existing requirement in the Queensland Health Public Health Management Guidelines, of restrictions on cases and some contacts while awaiting swab results, is currently under review.

Wave of COVID-19 outbreaks in Gold Coast residential aged care facilities after easing travel restrictions into Queensland.

Objective: This paper describes outbreaks of coronavirus disease 2019 (COVID-19) in Gold Coast residential aged care facilities (RACFs), in the two months following the easing of travel restrictions at Queensland's domestic border on 13 December 2021. Methods: This audit reviewed all RACF COVID-19 outbreaks notified to the Gold Coast Public Health Unit between 13 December 2021 and 12 February 2022. An outbreak was defined by the Communicable Diseases Network Australia guidelines current at the time. Results: There were 60 COVID-19 outbreaks across 57 RACFs during this period. In 44 outbreaks (73.3%), a staff member was identified as the primary or co-primary case. Transmission amongst residents occurred in 48 outbreaks (80.0%). The attack rates in staff and residents were 17.0% (n = 1,060) and 11.7% (n = 645) respectively. A higher number of males were hospitalised (n = 39: 57.4%) or died (n = 28: 66.7%) than were females (n = 29: 42.6%; n = 14: 33.3% respectively). Most resident cases (n = 565: 87.6%) had received two or more doses of a COVID-19 vaccine. In resident cases who were under-vaccinated (n = 76), twenty (26.3%) required hospitalisation and nine (11.8%) died. In resident cases who received two doses of vaccine (n = 484), forty-three (8.9%) were hospitalised and 27 (5.8%) died. In resident cases who had received three doses (n = 80), four (5.0%) were hospitalised and five (6.3%) died. Conclusions: COVID-19 caused significant morbidity and mortality in Gold Coast RACFs following the easing of border restrictions. Higher rates of hospitalisation and death occurred in males than in females, and in under-vaccinated resident cases than in those vaccinated with at least two doses of a COVID-19 vaccine. Implications for public health: These data support the need for up-to-date COVID-19 vaccination of residents in RACFs, continued surveillance and timely and appropriate implementation of public health guidelines to manage COVID-19 outbreaks in RACFs.

Protocol for a winter sentinel surveillance program of notifiable respiratory viruses in Queensland.

BACKGROUND: With the reduction in access to polymerase chain reaction (PCR) testing and changes in testing guidelines in Australia, a reduced number of people are seeking testing for coronavirus disease (COVID-19), limiting the opportunity to monitor disease transmission. Knowledge of community transmission of COVID-19 and other respiratory viruses is essential to better predict subsequent surges in cases during the pandemic to alert health services, protect vulnerable populations and enhance public health measures. We describe a methodology for a testing-based sentinel surveillance program to monitor disease in the community for early signal detection of SARS-CoV-2 and other respiratory viruses. METHODS/DESIGN: A longitudinal active testing-based sentinel surveillance program for respiratory viruses (including SARS-CoV-2, influenza A, influenza B and Respiratory Syncytial Virus) will be implemented in some regions of Queensland. Adults will be eligible for enrolment if they are part of specific community groups at increased risk of exposure and have not had a COVID-19 infection in the last 13 weeks. Recruitment via workplaces will occur in-person, via email and through online advertisement. Asymptomatic participants will be tested via PCR for SARS-CoV-2 infection by weekly self-collected nasal swabs. In addition, symptomatic participants will be asked to seek SARS-CoV-2 and additional respiratory virus PCR testing at nominated COVID-19 testing sites. SARS-CoV-2 and respiratory virus prevalence data will be analysed weekly and at the end of the study period. DISCUSSION: Once implemented, this surveillance program will determine the weekly prevalence of COVID-19 and other respiratory viruses in the broader community by testing a representative sample of adults, with an aim to detect early changes in the baseline positivity rate. This information is essential to define the epidemiology of SARS-CoV-2 in the community in near-real time to inform public health control measures and prepare health services and other stakeholders for a rise in service demand.

Defining the peak: Point prevalence of SARS-CoV-2 using randomised sampling.

Since Queensland eased border restrictions to the rest of Australia on 13 December 2021, notified cases of Coronavirus disease 2019 (COVID-19) dramatically increased, with the SARS-CoV-2 Omicron variant now the most widespread variant of concern: 145,881 cases and 13 deaths were recorded in Queensland in the month following the opening of the border. For an effective public health response to a highly transmissible disease, it is important to know the prevalence in the community, but the exponential increase in cases meant that many with symptoms had difficulty getting tested. We implemented a surveillance program on the Gold Coast that used a modified randomised household cluster survey method to estimate the point prevalence of individuals with SARS-CoV-2 detected by polymerase chain reaction (PCR). The estimated point prevalence of SARS-CoV-2 detected by PCR on self-collected swabs was 17.2% on the first visit to households (22 January 2022). This subsequently decreased to 5.2% (5 February 2022) and finally to 1.1% (19 February 2022). Out of 1,379 specimens tested over five weeks, 63 had detected SARS-CoV-2 and 35 (55.6%) were sequenced. All were SARS-CoV-2 variant: B.1.1.529 (i.e. Omicron). This surveillance program could be scaled up or reproduced in other jurisdictions to estimate the prevalence of COVID-19 in the community.Since Queensland eased border restrictions to the rest of Australia on 13 December 2021, notified cases of Coronavirus disease 2019 (COVID-19) dramatically increased, with the SARS-CoV-2 Omicron variant now the most widespread variant of concern: 145,881 cases and 13 deaths were recorded in Queensland in the month following the opening of the border. For an effective public health response to a highly transmissible disease, it is important to know the prevalence in the community, but the exponential increase in cases meant that many with symptoms had difficulty getting tested. We implemented a surveillance program on the Gold Coast that used a modified randomised household cluster survey method to estimate the point prevalence of individuals with SARS-CoV-2 detected by polymerase chain reaction (PCR). The estimated point prevalence of SARS-CoV-2 detected by PCR on self-collected swabs was 17.2% on the first visit to households (22 January 2022). This subsequently decreased to 5.2% (5 February 2022) and finally to 1.1% (19 February 2022). Out of 1,379 specimens tested over five weeks, 63 had detected SARS-CoV-2 and 35 (55.6%) were sequenced. All were SARS-CoV-2 variant: B.1.1.529 (i.e. Omicron). This surveillance program could be scaled up or reproduced in other jurisdictions to estimate the prevalence of COVID-19 in the community.

Informing the public health management of typhoid and paratyphoid: the Australian context.

OBJECTIVE: To examine outcomes of public health management of notified enteric fever cases in South-East Queensland over the past five years. METHODS: Notification records of typhoid and paratyphoid infection in South-East Queensland 2008-2012 (inclusive) were reviewed to determine likelihood of cases and contacts adhering to present or previous recommendations for faecal clearance/screening, duration of infectiousness of cases and extent of local transmission to contacts. RESULTS: Sixty-nine of 85 cases and 218 of 265 contacts submitted at least one faecal specimen. Cases were 2.7 (95%CI 1.2-6.0) and contacts were 4.4 (95%CI 3.0-6.4) times more likely to complete recommended faecal clearance/screening under previous compared to present guidelines (requiring more specimens). In ten cases with positive post-treatment specimens, last recorded infectiousness was 19 days to six months after notification. The documented rate of local transmission of infection was 18/1,000 contacts submitting at least one faecal specimen (95%CI 6-48/1,000). CONCLUSIONS: Local transmission risk of enteric fever in South-East Queensland is low, although small numbers of cases may have prolonged bacilli excretion post-treatment. More complex clearance/screening regimens are associated with decreased compliance. IMPLICATIONS: Pursuing extensive faecal clearance/screening regimens is unlikely to be effective in terms of public health management of enteric fever in South-East Queensland. We suggest a unified national approach focussing on cases/contacts at high risk of disease transmission.

An outbreak of shiga toxin-producing Escherichia coli infection associated with a school camp.

In November 2008, a case of Shiga toxin-producing Escherichia coli (STEC) infection was reported to the Brisbane Southside Public Health Unit. The case had participated in a school camp. Subsequent investigations confirmed 5 other asymptomatic cases among camp attendees or visitors. Examination of the camp water supply identified that most water sources had high levels of E. coli and did not meet the Australian Drinking Water Guidelines with STEC isolated from 2 water sources. This outbreak highlights the emerging issue of asymptomatic carriage of STEC and the importance of thorough maintenance and attention to drinking water supplies in the rural and school camp setting.

Human Hendra virus encephalitis associated with equine outbreak, Australia, 2008.

A recent Hendra virus outbreak at a veterinary clinic in Brisbane, Queensland, Australia, involved 5 equine and 2 human infections. In contrast to previous outbreaks, infected horses had predominantly encephalitic, rather than respiratory, signs. After an incubation period of 9-16 days, influenza-like illnesses developed in the 2 persons before progressing to encephalitis; 1 died. Both patients were given ribavirin. Basal serum and cerebrospinal fluid levels were 10-13 mg/L after intravenous administration and 6 mg/L after oral administration (isolate 90% inhibitory concentration 64 mg/L). Both patients were exposed to infected horses, 1 during the late incubation period in a horse. The attack rate for veterinary clinic staff exposed to infected horses was 10%. An isolate from this outbreak showed genetic heterogeneity with isolates from a concurrent, but geographically remote, outbreak and from previous outbreaks. Emergence of Hendra virus is a serious medical, veterinary, and public health challenge.

Outbreaks of Salmonella Typhimurium phage type 197 of multiple genotypes linked to an egg producer.

This paper describes outbreaks of Salmonella Typhimurium phage type 197 (STm197) linked to eggs from the farm of a single egg producer. Epidemiological and microbiological investigations (genotyping by multiple locus variable number tandem repeats analysis [MLVA]) identified outbreaks of STm197 with the same or closely-related MLVA profiles in a series of restaurants across Brisbane over 2 months. Environmental health investigations revealed that these restaurants were supplied with eggs from the same egg producer and that cross-contamination may have contributed to the outbreak. Environmental swabs taken from restaurant kitchens and the farm of the egg producer identified a number of salmonellas including STm197, many with MLVA profiles matching or closely related to the human strains from outbreak cases. A case-to-case comparison study showed a significant association between illness with 1 MLVA type and attending a restaurant during the 5 days before onset of illness (odds ratio [OR] 8.1, 95% confidence interval [CI] 1.8, 35.4). MLVA has become a valuable tool for S. Typhimurium surveillance and outbreak investigation. This outbreak further justifies the Commonwealth Government's decision to develop a draft national primary production and processing standard for eggs and egg products to address food safety risks posed by cracked and dirty eggs.

Reduction in invasive meningococcal disease in Queensland: a success for immunisation.

Since 2003, the Australian government has funded a conjugate serogroup C meningococcal vaccine for those aged over 1 year and born since 1 January 1984. This summary of the epidemiology of invasive meningococcal disease (IMD) in Queensland assesses the effect that the vaccination program has had on IMD notifications. In Queensland, IMD cases are notified to the Notifiable Conditions System by clinicians and laboratories. Additional surveillance data are collected by population health units from relatives of the case, the case and medical practitioners. In 2005, Queensland recorded its lowest number of cases and lowest incidence of IMD since statewide surveillance began. This remained low in 2006. The serogroup C rate in Queensland also declined to its lowest in 2006. The pattern of age specific incidence remains similar, though rates are lower in all but those aged less than 12 months. However, Indigenous rates are still twice non-Indigenous rates. The case fatality rate for IMD (all serogroups) has declined, possibly due to the reduced incidence of serogroup C and septicaemia cases. The program appears to have mostly achieved its aims of: reducing illness and death in the population at highest risk; inducing immunity in those who are vaccinated; and reducing the incidence of disease. However, there is considerable natural fluctuation in the rates of IMD and continued surveillance will be needed to monitor trends.