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Marsland MJ, Thomson TN, O'Brien HM, Peach E, Bellette J, Humphreys N, McKeon CA, Cross W, Moso MA, Batty M, Nicholson S, Karapanagiotidis T, Lim CK, Williamson DA, Winkler N, Koirala A, Macartney K, Glynn-Robinson A, Stewart T, Minko C, Snow KJ, Black J, Friedman ND. Serosurvey for Japanese encephalitis virus antibodies following an outbreak in an immunologically naïve population, Victoria, 2022: a cross-sectional study. Med J Aust 2024; 220:566-572. [PMID: 38803004 DOI: 10.5694/mja2.52344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 12/04/2023] [Indexed: 05/29/2024]
Abstract
OBJECTIVES To investigate the distribution and prevalence of Japanese encephalitis virus (JEV) antibody (as evidence of past infection) in northern Victoria following the 2022 Japanese encephalitis outbreak, seeking to identify groups of people at particular risk of infection; to investigate the distribution and prevalence of antibodies to two related flaviviruses, Murray Valley encephalitis virus (MVEV) and West Nile virus Kunjin subtype (KUNV). STUDY DESIGN Cross-sectional serosurvey (part of a national JEV serosurveillance program). SETTING Three northern Victorian local public health units (Ovens Murray, Goulburn Valley, Loddon Mallee), 8 August - 1 December 2022. PARTICIPANTS People opportunistically recruited at pathology collection centres and by targeted recruitment through community outreach and advertisements. People vaccinated against or who had been diagnosed with Japanese encephalitis were ineligible for participation, as were those born in countries where JEV is endemic. MAIN OUTCOME MEASURES Seroprevalence of JEV IgG antibody, overall and by selected factors of interest (occupations, water body exposure, recreational activities and locations, exposure to animals, protective measures). RESULTS 813 participants were recruited (median age, 59 years [interquartile range, 42-69 years]; 496 female [61%]); 27 were JEV IgG-seropositive (3.3%; 95% confidence interval [CI], 2.2-4.8%) (median age, 73 years [interquartile range, 63-78 years]; 13 female [48%]); none were IgM-seropositive. JEV IgG-seropositive participants were identified at all recruitment locations, including those without identified cases of Japanese encephalitis. The only risk factors associated with JEV IgG-seropositivity were age (per year: prevalence odds ratio [POR], 1.07; 95% CI, 1.03-1.10) and exposure to feral pigs (POR, 21; 95% CI, 1.7-190). The seroprevalence of antibody to MVEV was 3.0% (95% CI, 1.9-4.5%; 23 of 760 participants), and of KUNV antibody 3.3% (95% CI, 2.1-4.8%; 25 of 761). CONCLUSIONS People living in northern Victoria are vulnerable to future JEV infection, but few risk factors are consistently associated with infection. Additional prevention strategies, including expanding vaccine eligibility, may be required to protect people in this region from Japanese encephalitis.
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Affiliation(s)
- Madeleine J Marsland
- Victorian Department of Health, Melbourne, VIC, Australia
- National Centre for Epidemiology and Population Health, Australian National University, Canberra, ACT
| | - Tilda N Thomson
- Victorian Department of Health, Melbourne, VIC, Australia
- National Centre for Epidemiology and Population Health, Australian National University, Canberra, ACT
| | | | | | | | | | | | | | - Michael A Moso
- Victorian Infectious Diseases Reference Laboratory, Doherty Institute for Infection and Immunity, Royal Melbourne Hospital, Melbourne, VIC
| | - Mitchell Batty
- Victorian Infectious Diseases Reference Laboratory, Doherty Institute for Infection and Immunity, Royal Melbourne Hospital, Melbourne, VIC
| | - Suellen Nicholson
- Victorian Infectious Diseases Reference Laboratory, Doherty Institute for Infection and Immunity, Royal Melbourne Hospital, Melbourne, VIC
| | - Theo Karapanagiotidis
- Victorian Infectious Diseases Reference Laboratory, Doherty Institute for Infection and Immunity, Royal Melbourne Hospital, Melbourne, VIC
| | - Chuan Kok Lim
- Victorian Infectious Diseases Reference Laboratory, Doherty Institute for Infection and Immunity, Royal Melbourne Hospital, Melbourne, VIC
| | - Deborah A Williamson
- Victorian Infectious Diseases Reference Laboratory, Doherty Institute for Infection and Immunity, Royal Melbourne Hospital, Melbourne, VIC
| | - Noni Winkler
- National Centre for Immunisation Research and Surveillance, Sydney Children's Hospitals Network, Sydney, NSW
| | - Archana Koirala
- National Centre for Immunisation Research and Surveillance, Sydney Children's Hospitals Network, Sydney, NSW
| | - Kristine Macartney
- National Centre for Immunisation Research and Surveillance, Sydney Children's Hospitals Network, Sydney, NSW
| | - Anna Glynn-Robinson
- National Centre for Epidemiology and Population Health, Australian National University, Canberra, ACT
| | - Tony Stewart
- National Centre for Epidemiology and Population Health, Australian National University, Canberra, ACT
| | - Corinna Minko
- Victorian Department of Health, Melbourne, VIC, Australia
| | - Kathryn J Snow
- Victorian Department of Health, Melbourne, VIC, Australia
| | - Jim Black
- Victorian Department of Health, Melbourne, VIC, Australia
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Winkler NE, Koirala A, Kaur G, Prasad S, Hirani R, Baker J, Hoad V, Gosbell IB, Irving DO, Hueston L, O'Sullivan MV, Kok J, Dwyer DE, Macartney K. Seroprevalence of Japanese encephalitis virus-specific antibodies in Australia following novel epidemic spread: protocol for a national cross-sectional study. BMJ Open 2024; 14:e075569. [PMID: 38326269 PMCID: PMC10860057 DOI: 10.1136/bmjopen-2023-075569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 11/08/2023] [Indexed: 02/09/2024] Open
Abstract
INTRODUCTION Japanese encephalitis virus (JEV) is a mosquito-borne flavivirus that causes encephalitis and other morbidity in Southeast Asia. Since February 2022, geographically dispersed JEV human, animal and vector detections occurred on the Australian mainland for the first time. This study will determine the prevalence of JEV-specific antibodies in human blood with a focus on populations at high risk of JEV exposure and determine risk factors associated with JEV seropositivity by location, age, occupation and other factors. METHOD Samples are collected using two approaches: from routine blood donors (4153 samples), and active collections targeting high-risk populations (convenience sampling). Consent-based sampling for the latter includes a participant questionnaire on demographic, vaccination and exposure data. Samples are tested for JEV-specific total antibody using a defined epitope-blocking ELISA, and total antibody to Australian endemic flaviviruses Murray Valley encephalitis and Kunjin viruses. ANALYSIS Two analytic approaches will occur: descriptive estimates of seroprevalence and multivariable logistic regression using Bayesian hierarchical models. Descriptive analyses will include unadjusted analysis of raw data with exclusions for JEV-endemic country of birth, travel to JEV-endemic countries, prior JEV-vaccination, and sex-standardised and age-standardised analyses. Multivariable logistic regression will determine which risk factors are associated with JEV seropositivity likely due to recent transmission within Australia and the relative contribution of each factor when accounting for effects within the model. ETHICS National Mutual Acceptance ethical approval was obtained from the Sydney Children's Hospitals Network Human Research Ethics Committee (HREC). Local approvals were sought in each jurisdiction. Ethical approval was also obtained from the Australian Red Cross Lifeblood HREC. DISSEMINATION Findings will be communicated to participants and their communities, and human and animal health stakeholders and policy-makers iteratively and after final analyses. Understanding human infection rates will inform procurement and targeted allocation of limited JEV vaccine, and public health strategies and communication campaigns, to at-risk populations.
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Affiliation(s)
- Noni Ella Winkler
- National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases, Westmead, New South Wales, Australia
| | - Archana Koirala
- National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases, Westmead, New South Wales, Australia
- Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Guddu Kaur
- National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases, Westmead, New South Wales, Australia
- National Centre for Epidemiology and Population Health, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Shayal Prasad
- National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases, Westmead, New South Wales, Australia
| | - Rena Hirani
- Australian Red Cross Lifeblood, Sydney, New South Wales, Australia
- Faculty of Science and Engineering, Macquarie University, Macquarie Park, New South Wales, Australia
| | - Jannah Baker
- The University of Sydney, Sydney, New South Wales, Australia
| | - Veronica Hoad
- Australian Red Cross Lifeblood, Perth, Western Australia, Australia
| | - Iain B Gosbell
- Australian Red Cross Lifeblood, Sydney, New South Wales, Australia
- School of Medicine, Western Sydney University, Penrith South DC, New South Wales, Australia
| | - David O Irving
- Australian Red Cross Lifeblood, Sydney, New South Wales, Australia
- Faculty of Health, University of Technology Sydney, Broadway, New South Wales, Australia
| | - Linda Hueston
- New South Wales Health Pathology - Institute of Clinical Pathology and Medical Research, Westmead Hospital, Westmead, New South Wales, Australia
- Griffith University Menzies Health Institute Queensland, Brisbane, Queensland, Australia
| | - Matthew Vn O'Sullivan
- Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
- New South Wales Health Pathology - Institute of Clinical Pathology and Medical Research, Westmead Hospital, Westmead, New South Wales, Australia
| | - Jen Kok
- New South Wales Health Pathology - Institute of Clinical Pathology and Medical Research, Westmead Hospital, Westmead, New South Wales, Australia
| | - Dominic E Dwyer
- Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
- New South Wales Health Pathology - Institute of Clinical Pathology and Medical Research, Westmead Hospital, Westmead, New South Wales, Australia
| | - Kristine Macartney
- National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases, Westmead, New South Wales, Australia
- Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
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