Case-control study of leptospirosis in Aotearoa New Zealand reveals behavioural, occupational, and environmental risk factors

Nisa SOrtolani EVallée EMarshall JCollins-Emerson JYeung PPrinsen GWright JQuin TFayaz ALittlejohn SBaker MGDouwes JBenschop JHahné S2025-06-092025-06-092025-06-02Nisa S, Ortolani E, Vallée E, Marshall J, Collins-Emerson J, Yeung P, Prinsen G, Wright J, Quin T, Fayaz A, Littlejohn S, Baker MG, Douwes J, Benschop J. (2025). Case-control study of leptospirosis in Aotearoa New Zealand reveals behavioural, occupational, and environmental risk factors. Epidemiology and Infection. 153.0950-2688https://mro.massey.ac.nz/handle/10179/73012Leptospirosis in NZ has historically been associated with male workers in livestock industries; however, the disease epidemiology is changing. This study identified risk factors amid these shifts. Participants (95 cases:300 controls) were recruited nationwide between 22 July 2019 and 31 January 2022, and controls were frequency-matched by sex (90% male) and rurality (65% rural). Multivariable logistic regression models, adjusted for sex, rurality, age, and season - with one model additionally including occupational sector - identified risk factors including contact with dairy cattle (aOR 2.5; CI: 1.0-6.0), activities with beef cattle (aOR 3.0; 95% CI: 1.1-8.2), cleaning urine/faeces from yard surfaces (aOR 3.9; 95% CI: 1.5-10.3), uncovered cuts/scratches (aOR 4.6; 95% CI: 1.9-11.7), evidence of rodents (aOR 2.2; 95% CI: 1.0-5.0), and work water supply from multiple sources - especially creeks/streams (aOR 7.8; 95% CI: 1.5-45.1) or roof-collected rainwater (aOR 6.6; 95% CI: 1.4-33.7). When adjusted for occupational sector, risk factors remained significant except for contact with dairy cattle, and slaughter without gloves emerged as a risk (aOR 3.3; 95% CI: 0.9-12.9). This study highlights novel behavioural factors, such as uncovered cuts and inconsistent glove use, alongside environmental risks from rodents and natural water sources.(c) 2025 The Author/sCC BY 4.0https://creativecommons.org/licenses/by/4.0/LeptospirosisZoonoticRodentLivestockWaterCase-control study of leptospirosis in Aotearoa New Zealand reveals behavioural, occupational, and environmental risk factorsJournal article10.1017/S09502688251000711469-4409journal-articlee67