A systematic review on leptospirosis in cattle: a European perspective

Abstract Background Leptospirosis is a zoonotic disease which is globally distributed. Bovine leptospirosis often results in economic losses through its severe impact on reproduction performance. However, a clear overview of the disease characteristics in European cattle is lacking. The objective of this review was to summarise the current knowledge and state of the research on the epidemiology of bovine leptospirosis in Europe. Methodology We conducted a systematic literature review following the PRISMA guidelines. We screened four electronic databases (Pubmed, Web of Science, Scopus, CABI) and included studies published between 2001 and 2021, in English, German, and French. Identified papers were filtered according to predefined inclusion and exclusion criteria. Results Sixty-two studies were included. Reported seroprevalences were remarkably variable among studies, probably reflecting local variations but also heterogeneity in the study designs, laboratory methods, and sample sizes. The five most reported circulating serogroups in European cattle were Sejroe, Australis, Grippotyphosa, Icterohaemorrhagiae, and Pomona. Abortion and fertility disorders were the most frequently reported signs of leptospirosis in European cattle and were generally associated with chronic infections. The acute form primarily affected juveniles and foetuses. Risk factors positively associated with leptospirosis in cattle were diverse, related to environmental (e.g. geographic location), climatic (e.g. flooding), and medical (e.g. presence of other diseases) parameters, as well as farming practices (e.g. purchase policy, herd size) and individual factors (e.g. animal age and breed). Conclusions Clinical features of bovine leptospirosis in Europe cover a large range of signs and confirmation of infection requires laboratory tests. The epidemiology of the disease is very local, most probably influenced by context-specific factors. This work highlights several research gaps, including a lack of research data from several countries, a lack of methodological harmonisation, a lack of large-scale studies, an underrepresentation of beef herds in the studies, and a lack of molecular investigations. Author Summary Leptospirosis is a zoonotic disease that has been reported in cattle worldwide. This review systematically evaluated the available literature (2001-2021) on (i) the methods of diagnostics, (ii) (sero)prevalence, (iii) circulating serogroups/serovars, (iv) clinical signs, (v) and risk factors associated with leptospirosis in European cattle. We found that the prevalence of the disease was very variable among studies. Similarly, a wide range of clinical signs were described, but the most frequently reported ones were abortion and fertility disorders. Risk factors of infection in cattle included herd size, purchase of animals, access to pasture and natural water sources, contact with other animal species, presence of other diseases on farm, animal age, and occurrence of extreme weather events. This review highlights that leptospirosis should be considered as a differential diagnosis in case of abortion or reproductive failure in European cattle and emphasises the need for integrated disease prevention and control measures at farm or regional level. We identified several research gaps, particularly a lack of research data from several countries, a lack of large-scale studies, an underrepresentation of beef herds, and a limited use of molecular tools in the studies.