A One Health approach to leptospirosis: Current serosurveillance practices and climate change leave Australia at increasing risk

It is well established that climate change has led to an increase in extreme weather conditions.^1,2 Multiple significant flooding events in Queensland and New South Wales over the past five years have public health consequences for weeks or months in their aftermath, and this includes the risk of a surge in leptospirosis infections. Following the 2021 flood event in Far North Queensland, leptospirosis case notifications in the Cairns region reached 43 between January and May 2021, with close to three times higher notifications in February than over the preceding 5 years.³ Leptospirosis is a zoonotic disease of emerging global concern.^2,4–6 It is caused by spiral-shaped bacteria in the genus Leptospira which are classified into more than 250 pathogenic serovars based on antigenic differences.^5,7 Twenty four of the known serovars occur in Australia and are generally associated with specific mammalian hosts, such as rodents, macropods, dogs, pigs and cattle, with varying crossover of pathogenicity in humans.^5,8 The well-established interconnectedness of affected animals, humans and environmental conditions necessitates a One Health approach to leptospirosis.⁹