A Novel Web-Based Application for Influenza and COVID-19 Outbreak Detection and Response in Residential Aged Care Facilities.

Unlabelled: The use of innovative digital health technologies in public health is expanding quickly, including the use of these tools in outbreak response. The translation of a digital health innovation into effective public health practice is a complex process requiring diverse enablers across the people, process, and technology domains. This paper describes a novel web-based application that was designed and implemented by a district-level public health authority to assist residential aged care facilities in influenza and COVID-19 outbreak detection and response. It discusses some of the challenges, enablers, and key lessons learned in designing and implementing such a novel application from the perspectives of the public health practitioners (the authors) that undertook this project.

Detection of circulating normal and tumor plasma cells in newly diagnosed patients of multiple myeloma and their associations with clinical and laboratory parameters.

INTRODUCTION: Circulating plasma cells (CPCs) are frequently noted in variable frequencies in the entire spectrum of plasma cells neoplasms. With advent of high sensitivity multi-parametric flow cytometry, it is not only possible to detect CPCs present in very low numbers, but also to categorise them into circulating tumor plasma cells (CTPCs) and circulating normal plasma cells (CNPCs), based on their marker-profile. This study used multi-colour flow cytometry to evaluate the load of both CTPCs & CNPCs at the time of diagnosis and at six months' time-point of therapy, and evaluated associations of both with clinical and laboratory parameters. METHODS: Twenty one newly diagnosed MM patients were enrolled. Six to nine millilitres of EDTA-anticoagulated peripheral blood sample was used for flow cytometry. A ten colour antibody panel was used for analysis of CPCs, which were categorised further into CTPCs and CNPCs. Approximately 4.8 million events were acquired for the analysis. The percentage &absolute numbers of CTPCs and CNPCs were noted and the proportion of CTPCs out of all CPCs (CTPCs + CNPCs) were also calculated for evaluating their statistical associations. RESULTS: All 21 patients of newly diagnosed MM showed presence of CPCs (CTPCs and/or CNPCs) at the time of diagnosis. The CTPCs were detected in 76 % of the study population. The median percentage and absolute counts of CTPCs were 0.52 % and 54.9 cells /µL, respectively. CNPCs were found in 95 % and the median percentage and absolute counts of CNPCs were 0.025 % and 2.66 cells/µL. After six months of therapy, CPCs (CTPCs and/or CNPCs) were found in all nine patients evaluated for this assay. CTPCs were found 33 %, with a median of 0.075 % and CNPCs were found in 89 % with a median of 0.01 %. Our study showed that the load of CTPCs was found to be higher in patients with presence of lytic bone lesions, plasmacytoma, presence of PCs on peripheral blood film by light microscopy, presence of Chr 1p32 deletion, expression of CD56 and CD81 on CTPCs, and in patients with absence of very good partial response (VGPR). Conversely, the load of CTPCs was significantly lower in patients with concomitant amyloidosis. Also, percentage of bone marrow plasma cells exhibited a significant positive correlation with the absolute count of CTPCs. We observed that the mean percentage of CNPCs was significantly higher in female patients. The load of CNPCs was lower in patients with thrombocytopenia and with hypoalbuminemia. CONCLUSION: Increased burden of CTPCs was associated with presence of lytic lesions, plasmacytomas, Chr 1p32 deletion, expression of CD56 and CD81 on tumor cells and with failure to achieve very good partial response. The CNPCs were lower in patients with thrombocytopenia and with hypoalbuminemia. To best ot our knowledge, this is the first study from India on the relevance of circulating tumor plasma cells and the first study in the world to analyse the associations of circulating normal plasma cells in newly diagnosed patients of multiple myeloma. The study also highlights the utility of multi-parametric flow cytometry in identification and enumeration of circulating plasma cells. MICRO ABSTRACT: Circulating plasma cells indicates poorer outcomes in patients of multiple myeloma. Twenty one newly diagnosed multiple myeloma patients were evaluated by flow cytometry to enumerate and characterise circulating tumor plasma cells (CTPCs) and circulating normal plasma cells (CNPCs). Higher load of CTPCs correlated with known poor prognostic markers and poor response to therapy.

Respiratory syncytial virus disease morbidity in Australian infants aged 0 to 6 months: a systematic review with narrative synthesis.

BACKGROUND: A significant proportion of the global respiratory syncytial virus (RSV) associated morbidity is accounted for by infants aged 0 to 6 months, who are particularly vulnerable to severe disease. In 2015, 44% of global hospitalisations in infants in this age group were secondary to RSV. The objective of this systematic review is to appraise and synthesise the local evidence of RSV infection morbidity among Australian infants aged 0 to 6 months and to assess the implications for future immunisation strategies. METHODS: Electronic databases (Medline, Embase, Pubmed and Global Health) were searched for full-text articles published between 2000 and 2023 in English language. Studies that examined markers of RSV disease morbidity in infants aged 0 to 6 months in Australia who had laboratory confirmed RSV infection were eligible for inclusion. The outcomes of interest were incidence, prevalence, testing rate, positivity rate, mortality, emergency department visits, community health visits, hospitalisation, intensive care unit admission, supplementary oxygen use, mechanical ventilation, risk factors for disease severity and monoclonal antibody use. RESULTS: The database search identified 469 studies. After removal of duplicates and full-text review, 17 articles were eligible for inclusion. This review was reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Synthesis without meta-analysis guidelines. CONCLUSIONS: Qualitative analysis of the included studies showed that Australian infants aged 0 to 6 months have higher rates of RSV testing, positivity and incidence; and more likely to develop severe disease that requires hospitalisation, intensive care unit admission or respiratory support, compared to children and adults of all ages. Aboriginal and Torres Strait Islander infants aged 0 to 6 months demonstrated higher rates of RSV infection and hospitalisation, compared to non-Indigenous infants. Age-related trends persisted in geographic areas with varying seasonal transmission of RSV, and during the SARS-CoV-2 pandemic. Passive immunisation strategies targeting infants in their first 6 months of life, either via vaccination of pregnant women or administration of long-acting monoclonal antibody during infancy, could effectively reduce RSV disease burden in Australia.

An Australian aged care home for people subject to homelessness: health, wellbeing and cost-benefit.

BACKGROUND: Older people subject to homelessness face many challenges including poor health status, geriatric syndromes, and depression, coupled with barriers in accessing health and aged care services. Many are in need of formal aged care at a younger age than the general population, yet, in Australia, specialised aged-care services to support this vulnerable cohort are limited. METHODS: This study was an evaluation of a new purpose-built aged care home for people with high care needs and who are homeless or at risk of homelessness. Over the first 12 months post-admission, the study examined: (1) changes in residents' physical, mental, psychological and social health, and (2) the costs incurred by the study cohort, including any cost benefit derived. RESULTS: Thirty-five residents enrolled in the study between March 2020 - April 2021. At admission, almost half of residents were within the range for dementia, the majority were frail, at high risk for falls, and had scores indicative of depression. Over time, linear mixed-effect models showed significant improvement in personal wellbeing scores, with clinically significant improvements in overall health related quality of life. Levels of physical functional independence, frailty, and global cognition were stable, but cognitive functional ability declined over time. Comparison of 12 month pre- and post- admission cost utility data for a smaller cohort (n = 13) for whom complete data were available, suggested an average per resident saving of approximately AU$32,000, while the QALY indicators remained stable post-admission. CONCLUSION: While this was a small study with no control group, these preliminary positive outcomes add to the growing body of evidence that supports the need for dedicated services to support older people subject to homelessness.

Protecting Older Adult Residents in Care Facilities Against Influenza and COVID-19 Using the Influenza Communication, Advice and Reporting (FluCARE) App: Prospective Cohort Mixed Methods Study.

BACKGROUND: Early detection and response to influenza and COVID-19 outbreaks in aged care facilities (ACFs) are critical to minimizing health impacts. The Sydney Local Health District (SLHD) Public Health Unit (PHU) has developed and implemented a novel web-based app with integrated functions for online line listings, detection algorithms, and automatic notifications to responders, to assist ACFs in outbreak response. The goal of the Influenza Outbreak Communication, Advice and Reporting (FluCARE) app is to reduce time delays to notifications, which we hope will reduce the spread, duration, and health impacts of an influenza or COVID-19 outbreak, as well as ease workload burdens on ACF staff. OBJECTIVE: The specific aims of the study were to (1) evaluate the acceptability and user satisfaction of the implementation and use of FluCARE in helping ACFs recognize, notify, and manage influenza and COVID-19 outbreaks in their facility; (2) identify the safety of FluCARE and any potential adverse outcomes of using the app; and (3) identify any perceived barriers or facilitators to the implementation and use of FluCARE from the ACF user perspective. METHODS: The FluCARE app was piloted from September 2019 to December 2020 in the SLHD. Associated implementation included promotion and engagement, user training, and operational policies. Participating ACF staff were invited to complete a posttraining survey. Staff were also invited to complete a postpilot evaluation survey that included the user Mobile Application Rating Scale (uMARS) measuring app acceptance, utility, and barriers and facilitators to use. An issues log was also prospectively maintained to assess safety. Survey data were analyzed descriptively or via content analysis where appropriate. RESULTS: Surveys were completed by 31 consenting users from 27 ACFs. FluCARE was rated 3.91 of 5 overall on the uMARS. Of the 31 users, 25 (80%) would definitely use FluCARE for future outbreaks, and all users agreed that the app was useful for identifying influenza and COVID-19 outbreaks at their facilities. There were no reported critical issues with incorrect or missed outbreak detection. User training, particularly online training modules, and technical support were identified as key facilitators to FluCARE use. CONCLUSIONS: FluCARE is an acceptable, useful, and safe app to assist ACF staff with early detection and response to influenza and COVID-19 outbreaks. This study supports feasibility for ongoing implementation and efficacy evaluation, followed by scale-up into other health districts in New South Wales.

Engaging with culturally and linguistically diverse communities during a COVID-19 outbreak: a NSW Health interagency public health campaign.

OBJECTIVES: To report on efforts to engage culturally and linguistically diverse (CALD) communities to provide an effective and appropriate public health response to coronavirus disease 2019 (COVID-19), and to report how a tailored, interagency response addressing specific community needs was rapidly rolled out in a pandemic setting. Type of program or service: A novel, rapid, interagency public health campaign led by NSW Health and Sydney Local Health District (SLHD) was established in response to a local outbreak of COVID-19 in the multicultural suburb of Lakemba, in Sydney's south west, in October 2020. The public education and testing campaign was run over 2 weeks and involved in-language development of COVID-19 resources, establishment of a local pop-up testing clinic, 'COVID Safe' inspections of local businesses, engagement with local community leaders and distribution of written and verbal in-language education by cultural support workers. METHODS: We describe the campaign impact in engaging CALD communities in a pandemic setting, including the impact on COVID-19 testing rates, identification of close contacts and engagement with local businesses, as well as learnings from a multi-agency debrief at the conclusion of the campaign. RESULTS: There was an 87% increase in COVID-19 testing in the local area during the campaign. Despite 890 close contacts being identified during the outbreak, only 17 cases of COVID-19 were identified. Regulators visited 127 local businesses to provide 'COVID Safe' education and advice. SLHD cultural support personnel worked with the community to provide verbal and written in-language resources and education. Community and religious leaders were engaged to act as 'COVID Safe' champions. LESSONS LEARNT: A key to the success of the Lakemba campaign was the rapid, multi-agency collaboration between NSW Health, SLHD and regulators. An important lesson from the COVID-19 pandemic has been the importance of providing a flexible, tailored public health response that reacts to the target community's needs. This is even more important in our CALD communities, where mainstream health messages are insufficient. The Lakemba campaign is an example of how such a response can be undertaken rapidly while maintaining the key principles of community partnership, engagement and equity.

Sydney Local Health District's Integrated Response to the COVID-19 Pandemic: A Descriptive Study.

Introduction: Sydney Local Health District (SLHD) is a local health district in the state of New South Wales in Australia responsible for providing health services to the centre and inner west of the Sydney metropolitan area. SLHD adopted, during the COVID-19 pandemic, an integrated virtual and community care approach to manage quarantine and protect the health and wellbeing of the population. Description: The case study describes the roles of the different agencies and teams in the first six months of the pandemic across four key functions of 1) rapid screening and testing; 2) reaching the community; 3) effective quarantine and ongoing care; and 4) infrastructure, pathology and staff education. Discussion: The "whole of system" approach proved to be an effective method of delivering care that reduced community anxiety, improved and created relationships between existing and new internal and external stakeholders, and changed the community and health sector's perspective on the importance of virtual care. Conclusion: This case study describes the importance of well-integrated, decentralised and funded public health system in response to the COVID-19 pandemic.

Audit of the Sydney Local Health District Public Health Unit notification and contact tracing system during the first wave of COVID-19.

OBJECTIVE: To conduct a real-time audit to assess a Continuous Quality Improvement (CQI) activity to improve the quality of public health data in the Sydney Local Health District (SLHD) Public Health Unit during the first wave of COVID-19. METHODS: A real-time audit of the Notifiable Conditions Information Management System was conducted for positive cases of COVID-19 and their close contacts from SLHD. After recording missing and inaccurate data, the audit team then corrected the data. Multivariable regression models were used to look for associations with workload and time. RESULTS: A total of 293 cases were audited. Variables measuring completeness were associated with improvement over time (p<0.0001), whereas those measuring accuracy reduced with increased workload (p=0.0003). In addition, the audit team achieved 100% data quality by correcting data. CONCLUSION: Utilising a team, separate from operational staff, to conduct a real-time audit of data quality is an efficient and effective way of improving epidemiological data. Implications for public health: Implementation of CQI in a public health unit can improve data quality during times of stress. Auditing teams can also act as an intervention in their own right to achieve high-quality data at minimal cost. Together, this can result in timely and high-quality public health data.

Web-Based Apps for Responding to Acute Infectious Disease Outbreaks in the Community: Systematic Review.

BACKGROUND: Web-based technology has dramatically improved our ability to detect communicable disease outbreaks, with the potential to reduce morbidity and mortality because of swift public health action. Apps accessible through the internet and on mobile devices create an opportunity to enhance our traditional indicator-based surveillance systems, which have high specificity but issues with timeliness. OBJECTIVE: The aim of this study is to describe the literature on web-based apps for indicator-based surveillance and response to acute communicable disease outbreaks in the community with regard to their design, implementation, and evaluation. METHODS: We conducted a systematic search of the published literature across four databases (MEDLINE via OVID, Web of Science Core Collection, ProQuest Science, and Google Scholar) for peer-reviewed journal papers from January 1998 to October 2019 using a keyword search. Papers with the full text available were extracted for review, and exclusion criteria were applied to identify eligible papers. RESULTS: Of the 6649 retrieved papers, 23 remained, describing 15 web-based apps. Apps were primarily designed to improve the early detection of disease outbreaks, targeted government settings, and comprised either complex algorithmic or statistical outbreak detection mechanisms or both. We identified a need for these apps to have more features to support secure information exchange and outbreak response actions, with a focus on outbreak verification processes and staff and resources to support app operations. Evaluation studies (6 out of 15 apps) were mostly cross-sectional, with some evidence of reduction in time to notification of outbreak; however, studies lacked user-based needs assessments and evaluation of implementation. CONCLUSIONS: Public health officials designing new or improving existing disease outbreak web-based apps should ensure that outbreak detection is automatic and signals are verified by users, the app is easy to use, and staff and resources are available to support the operations of the app and conduct rigorous and holistic evaluations.

Control of COVID-19 in Australia through quarantine: the role of special health accommodation (SHA) in New South Wales, Australia.

BACKGROUND: The first COVID-19 cases were diagnosed in Australia on 25 January 2020. Initial epidiemiology showed that the majority of cases were in returned travellers from overseas. One aspect of Public Health response was to introduce compulsory 14 day quarantine for all travellers returning to New South Wales (NSW) by air or sea in Special Health Accommodation (SHA). We aim to outline the establishment of a specialised health quarantine accommodation service in the context of the COVID-19 pandemic, and describe the first month of COVID-19 screening. METHODS: The SHA was established with a comprehensive governance structure, remote clinical management through Royal Prince Alfred Virtual Hospital (rpavirtual) and site management with health care workers, NSW Police and accommodation staff. RESULTS: From 29 March to 29 April 2020, 373 returning travellers were admitted to the SHA from Sydney Airport. 88 (26.1%) of those swabbed were positive for SARS-CoV 2. The day of diagnosis of COVID-19 varied from Day 1 to Day 13, with 63.6% (n = 56) of these in the first week of quarantine. 50% of the people in the SHA were referred to rpavirtual for ongoing clinical management. Seven people required admission to hospital for ongoing clinical care. CONCLUSION: The Public Health response to COVID-19 in Australia included early and increased case detection through testing, tracing of contacts of confirmed cases, social distancing and prohibition of gatherings. In addition to these measures, the introduction of mandated quarantine for travellers to Australia was integral to the successful containment of COVID-19 in NSW and Australia through the prevention of transmission locally and interstate from returning travellers.

Factors associated with adverse outcomes during influenza outbreaks in aged care facilities.

OBJECTIVE: To explore factors associated with adverse outcomes during influenza outbreaks in residential aged care facilities. METHODS: A retrospective cohort study of all outbreaks reported to three Sydney metropolitan Public Health Units during 2017. RESULTS: A total of 123 outbreaks affected 1,787 residents and 543 staff. Early notification to a Public Health Unit was associated with shorter outbreak duration (p<0.001; B=0.674). Resident attack rates and resident mortality rates were lower in outbreaks notified early, on univariate analysis (p=0.034 and p=0.048 respectively) but not on an adjusted model. Staff attack rates were significantly associated with resident attack rates (p=0.001; B=0.736). Data on staff vaccination rates was incomplete and reported coverage rates were low (median 39%). Resident vaccination coverage ≥95% was associated with shorter outbreak duration in univariate testing but not on an adjusted model. CONCLUSIONS: Early public health notification is associated with improved outbreak parameters; sick staff may pose a risk to residents, yet vaccination rates are low. Resident vaccination may also be valuable. Implications for public health: Measures that facilitate early PHU involvement in influenza outbreaks should be implemented, such as compulsory reporting requirements and processes that permit easier notification through technology. Actions that enhance staff and resident vaccination coverage should also be undertaken.

Surveillance methods to detect the impact of a significant cold chain breach.

In January 2015, a significant cold chain breach on a postnatal ward in a tertiary hospital in Sydney, Australia was noted to have been occurring since August 2013. Surveillance, amongst the 1178 mothers and 1178 babies affected, for vaccine-preventable diseases (VPDs) and adverse events following immunisation (AEFIs) using linkage with a notifiable diseases database was subsequently undertaken; no directly related instances of VPDs or AEFIs were detected. We evaluate this novel systematic surveillance method which has not been previously reported to determine whether it is effective in determining the impact of cold chain breaches on an individual and population level. The recommendation for revaccination of the affected mothers and subsequent surveillance was resource-intensive and future studies related to such incidents should focus on detailing the resources used to allow the costs versus benefits of such systematic surveillance to be determined.

Culture-positive shigellosis cases are epidemiologically different to culture-negative/PCR-positive cases.

OBJECTIVE: To review the epidemiological differences between culture-positive and culture-negative (but ipaH PCR-positive) cases of shigellosis in Sydney Local Health District (SLHD), NSW, to inform whether changes to the national case definition for shigellosis are required. METHODS: An audit of all cases of shigellosis (culture-positive vs. culture-negative/PCR-positive) in SLHD from 1 January 2013 to 30 June 2015 was conducted and demographic, clinical and risk factors were analysed and compared between these groups. RESULTS: Of the 148 shigellosis cases notified to SLHD, 122 cases (85 culture-positive vs. 37 culture-negative) were included for analysis. Culture-positive cases were more likely than culture-negative/PCR-positive cases to have experienced at least three symptoms (OR 3.18, 95%CI 1.3-7.5), been hospitalised (OR 4.2, 95%CI 1.4-13.2), and have had men-who-have-sex-with-men exposure identified as the source of their infection (OR 28.7, 95%CI 6.2-132.6). CONCLUSIONS: This study has identified that culture-positive vs. culture-negative/PCR-positive shigellosis cases in NSW differ by clinical severity and risk factors for infection. Implications for public health: The study findings warrant further research to determine the true diagnostic prevalence of Shigella in the culture-negative/PCR-positive group in the Australian context, in order to inform further changes to the national case definition for shigellosis.

Cardiovascular Disease & Cancer Risk Among South Asians: Impact of Sociocultural Influences on Lifestyle and Behavior.

A comprehensive literature review revealed cultural beliefs, societal obligations, and gender roles within the South Asian community to be indirect contributors to the health of South Asian immigrants (SAIs). Health professionals need to increase their work with SAI communities to change less beneficial cultural elements such as misconceptions about health and exercise, and lack of communication when using alternative medicines. Community engaged efforts and continuing medical education are both needed to improve the health of the South Asian immigrant population in a culturally appropriate manner.

Understanding barriers to effective management of influenza outbreaks by residential aged care facilities.

OBJECTIVE: To identify the perceived barriers to the implementation of the Australian national guidelines on influenza outbreak management with Sydney Local Health District (SLHD) residential aged care facility (RACF) staff. METHODS: All SLHD RACFs were invited to participate in a telephone interview. The questionnaire collected information about demographic characteristics and participants' level of agreement with statements regarding perceived barriers to implementing the national guidelines for influenza outbreak management. RESULTS: Twenty-eight of 61 RACFs (46%) participated in the study. The three most common barriers identified were as follows: scepticism towards staff influenza vaccination (n = 13, 46%); the effort required to read the national guidelines (n = 11, 39%); and lack of infrastructure to physically separate residents during an outbreak (n = 10, 36%). CONCLUSIONS: We recommend implementing and evaluating programmes which address misconceptions about influenza vaccination amongst RACF staff. Further, all RACF staff, including care staff, should receive targeted education on the role of infection control in influenza outbreak management.

Age and cause-of-death contributions to area socioeconomic, sex and remoteness differences in life expectancy in New South Wales, 2010-2012.

OBJECTIVES: To determine age group- and cause-of-death-specific contributions to area socioeconomic status (SES), sex and remoteness life expectancy inequalities. METHODS: Mortality and estimated residential population data from New South Wales, Australia, over 2010-2012 was used to calculate life expectancy. Inequalities by sociodemographic groups were partitioned into age group- and cause-of-death-specific contributions. RESULTS: The largest contributions to SES differentials in life expectancy were observed at 60-84 years of age; for cancer, cardiovascular, endocrine and respiratory causes of death; and additionally external causes of death for males. Sex inequalities ranged from 3.6 to 5.2 years, with common causes of death such as cardiovascular disease and cancer in late adulthood (60+ years) accounting for the bulk of the differences. Smaller differences in life expectancy were observed by remoteness, with the largest contributions observed in ages 85 years and above, and for cardiovascular, mental, cancer and external causes of death. CONCLUSIONS: Common causes of death in late adulthood accounted for the bulk of life expectancy inequalities. Implications for public health: Development of policy and interventions aimed at addressing social determinants, such as proposed by the WHO's Global Plan of Action, are needed to help reduce sociodemographic inequalities in lifespan.

Lessons Learned From Implementing an Incident Command System During a Local Multiagency Response to a Legionnaires' Disease Cluster in Sydney, NSW.

The incident command system (ICS) provides a common structure to control and coordinate an emergency response, regardless of scale or predicted impact. The lessons learned from the application of an ICS for large infectious disease outbreaks are documented. However, there is scant evidence on the application of an ICS to manage a local multiagency response to a disease cluster with environmental health risks. The Sydney Local Health District Public Health Unit (PHU) in New South Wales, Australia, was notified of 5 cases of Legionnaires' disease during 2 weeks in May 2016. This unusual incident triggered a multiagency investigation involving an ICS with staff from the PHU, 3 local councils, and the state health department to help prevent any further public health risk. The early and judicious use of ICS enabled a timely and effective response by supporting clear communication lines between the incident controller and field staff. The field team was key in preventing any ongoing public health risk through inspection, sampling, testing, and management of water systems identified to be at-risk for transmission of legionella. Good working relationships between partner agencies and trust in the technical proficiency of environmental health staff aided in the effective management of the response. (Disaster Med Public Health Preparedness. 2018;12:539-542).

Foodborne Illness Outbreak Investigation in a High-Profile Sports Club.

A foodborne illness outbreak involving an elite sports team was investigated by a public health unit in Sydney, Australia. An epidemiological association was established between gastrointestinal illness and the consumption of food supplied by an external caterer, with a lamb meal most strongly associated with illness. Genetically identical Salmonella isolates were identified from clinical specimens, residual food items, and an environmental swab taken from the catering premises. The training schedule and other club operations were significantly affected by this outbreak. Increased susceptibility due to regular shared activities and the potential for significant impact upon performance indicates that sports clubs must ensure that food suppliers comply with the highest standards of hygiene. Collaboration with public health authorities assists in source identification and prevention of further transmission.