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Leptospirosis in New Zealand has been strongly associated with animal-contact occupations and with serovars Hardjo and Pomona. However, recent data suggest changes in these patterns, hence, serovar-specific epidemiology of leptospirosis from 1999 to 2017 was investigated. The 19-year average annual incidence is 2.01/100,000. Early (1999–2007) and late (2008–2017) study period comparisons showed a significant increase in notifications with serovar Ballum (IRR: 1.59, 95% CI: 1.22–2.09) in all cases and serovar Tarassovi (IRR: 1.75, 95% CI: 1.13–2.78) in Europeans and a decrease in notifications with serovars Hardjo and Pomona in all cases. Incidences of Ballum peaked in winter, Hardjo peaked in spring and Tarassovi peaked in summer. Incidence was highest in Māori (2.24/100,000) with dominant serovars being Hardjo and Pomona. Stratification by occupation showed meat workers had the highest incidence of Hardjo (57.29/100,000) and Pomona (45.32/100,000), farmers had the highest incidence of Ballum (11.09/100,000) and dairy farmers had the highest incidence of Tarassovi (12.59/100,000). Spatial analysis showed predominance of Hardjo and Pomona in Hawke's Bay, Ballum in West Coast and Northland and Tarassovi in Waikato, Taranaki and Northland. This study highlights the serovar-specific heterogeneity of human leptospirosis in New Zealand that should be considered when developing control and prevention strategies. [ABSTRACT FROM AUTHOR]

Leptospira infection in dairy cattle and leptospirosis in dairy farm workers were common in New Zealand prior to the introduction of dairy cattle vaccination in the 1980s. Despite widespread vaccination within the dairy industry, the long-term effectiveness of vaccination and current Leptospira exposure status remained unknown. A cross-sectional study was conducted from January-April 2016 to investigate the prevalence of pathogenic Leptospira spp. DNA in urine at cow and herd level, and its relationship to five Leptospira serovars known to be endemic. Two hundred dairy farms were randomly selected from the national database. Twenty paired blood and urine samples were collected on each farm from adult cows (n = 4000). Sera were tested using the Microscopic Agglutination Test against serovars Hardjobovis (termed Hardjo), Pomona, Copenhageni, Ballum and Tarassovi with titres ≥48 being considered positive. Urine was tested using quantitative real-time PCR (qPCR) that amplifies the gryB gene. All but one herd had been vaccinated with a bivalent Hardjo/Pomona or trivalent vaccine incorporating Copenhageni. In total, 2.4% of cows were urine qPCR positive and 27% of farms had at least one urine qPCR positive cow. Overall 63% of cows were seropositive to one or more serovars: 44% for Hardjo, 28% for Pomona, 15% for Copenhageni (in vaccinated herds), and for unvaccinated cows: 1% for Copenhageni, and 3% for Ballum and 17% for Tarassovi. Of the 94 qPCR urine-positive cows, 51 were seropositive to Tarassovi, 3 to Ballum, 3 to Copenhageni, 24 to Hardjo, and 17 to Pomona, the latter two presumably reflecting vaccination titres. A strong association was found between shedding and serology for Tarassovi. While there was no evidence that current vaccination programmes were ineffective in protecting against their target serovars, serovar Tarassovi has apparently emerged in NZ dairy cattle. As Tarassovi is currently not included in vaccines and is prevalent in notified leptospirosis cases in dairy workers, we concluded that this serovar poses a public health risk. [ABSTRACT FROM AUTHOR]