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      Leptospirosis in Aotearoa New Zealand: Protocol for a Nationwide Case-Control Study


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          In Aotearoa New Zealand, 90% of patients with notified leptospirosis (a zoonotic bacterial disease) have been men working in agricultural industries. However, since 2008, the epidemiology of notified cases has been gradually changing, that is, more women are affected; there are more cases associated with occupations traditionally not considered high risk in New Zealand; infecting serovars have changed; and many patients experience symptoms long after infection. We hypothesized that there is a shift in leptospirosis transmission patterns with substantial burden on affected patients and their families.


          In this paper, we aimed to describe the protocols used to conduct a nationwide case-control study to update leptospirosis risk factors and follow-up studies to assess the burden and sources of leptospirosis in New Zealand.


          This study used a mixed methods approach, comprising a case-control study and 4 substudies that involved cases only. Cases were recruited nationwide, and controls were frequency matched by sex and rurality. All participants were administered a case-control questionnaire (study 1), with cases being interviewed again at least 6 months after the initial survey (study 2). A subset of cases from two high-risk populations, that is, farmers and abattoir workers, were further engaged in a semistructured interview (study 3). Some cases with regular animal exposure had their in-contact animals (livestock for blood and urine and wildlife for kidney) and environment (soil, mud, and water) sampled (study 4). Patients from selected health clinics suspected of leptospirosis also had blood and urine samples collected (study 5). In studies 4 and 5, blood samples were tested using the microscopic agglutination test to test for antibody titers against Leptospira serovars Hardjo type bovis, Ballum, Tarassovi, Pomona, and Copenhageni. Blood, urine, and environmental samples were also tested for pathogenic Leptospira DNA using polymerase chain reaction.


          Participants were recruited between July 22, 2019, and January 31, 2022, and data collection for the study has concluded. In total, 95 cases (July 25, 2019, to April 13, 2022) and 300 controls (October 19, 2019, to January 26, 2022) were interviewed for the case-control study; 91 cases participated in the follow-up interviews (July 9, 2020, to October 25, 2022); 13 cases participated in the semistructured interviews (January 26, 2021, to January 19, 2022); and 4 cases had their in-contact animals and environments sampled (October 28, 2020, and July 29, 2021). Data analysis for study 3 has concluded and 2 manuscripts have been drafted for review. Results of the other studies are being analyzed and the specific results of each study will be published as individual manuscripts..


          The methods used in this study may provide a basis for future epidemiological studies of infectious diseases.

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          Most cited references60

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                Author and article information

                JMIR Res Protoc
                JMIR Res Protoc
                JMIR Research Protocols
                JMIR Publications (Toronto, Canada )
                8 June 2023
                : 12
                : e47900
                [1 ] Molecular Epidemiology and Public Health Laboratory School of Veterinary Science Massey University Palmerston North New Zealand
                [2 ] EpiCentre School of Veterinary Science Massey University Palmerston North New Zealand
                [3 ] School of Mathematical and Computational Sciences Massey University Palmerston North New Zealand
                [4 ] School of Social Work Massey University Palmerston North New Zealand
                [5 ] School of People, Environment and Planning Massey University Palmerston North New Zealand
                [6 ] Research Centre for Hauora and Health Massey University Wellington New Zealand
                [7 ] Department of Public Health University of Otago Wellington New Zealand
                [8 ] Enteric and Leptospira Reference Laboratory Institute of Environmental Science and Research Christchurch New Zealand
                [9 ] Goodfellow Unit University of Auckland Auckland New Zealand
                [10 ] College of Health Massey University Palmerston North New Zealand
                [11 ] Unité Mixte de Recherche, Animal, Santé, Territoires, Risques et Ecosystèmes, Centre de coopération internationale en recherche agronomique pour le développement, Institut national de la recherche agronomique University of Montpellier Plateforme Technologique Cyclotron Réunion Océan Indien Sainte-Clotilde, La Réunion France
                Author notes
                Corresponding Author: Shahista Nisa s.nisa@ 123456massey.ac.nz
                Author information
                ©Shahista Nisa, Emilie Vallee, Jonathan Marshall, Julie Collins-Emerson, Polly Yeung, Gerard Prinsen, Jeroen Douwes, Michael G Baker, Jackie Wright, Tanya Quin, Maureen Holdaway, David A Wilkinson, Ahmed Fayaz, Stuart Littlejohn, Jackie Benschop. Originally published in JMIR Research Protocols (https://www.researchprotocols.org), 08.06.2023.

                This is an open-access article distributed under the terms of the Creative Commons Attribution License ( https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work, first published in JMIR Research Protocols, is properly cited. The complete bibliographic information, a link to the original publication on https://www.researchprotocols.org, as well as this copyright and license information must be included.

                : 4 April 2023
                : 24 April 2023
                : 27 April 2023
                : 30 April 2023
                Custom metadata
                The proposal for this study was peer-reviewed by H Schwermer; externally peer-reviewed by Health Research Council of New Zealand (Grafton, Auckland). See the Multimedia Appendices for the peer-review reports;

                leptospirosis,leptospira,case-control study,new zealand,mixed methods,protocol,indigenous health,public health,one health


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