Epidemiology of leptospirosis in dairy farm workers in the Manawatu. Part II. A case-control study of high and low risk farms

Authors: Blackmore DK, Schollum LM, Marshall RB, Mackintosh CG
Publication: New Zealand Veterinary Journal, Volume 30, Issue 6, pp 73-76, Jun 1982
Publisher: Taylor and Francis

Animal type: Cattle, Human, Livestock, Production animal, Ruminant
Subject Terms: Bacterial, Biosecurity, Clinical pathology, Diagnostic procedures, Disease control/eradication, Epidemiology, Zoonosis, Disease/defect, Infectious disease, Public health
Article class: Scientific Article

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Abstract: Subsequent to a cross-sectional serological survey of Manawatu dairy farm workers, a case-control study was carried out to investigate the correlation between titres to leptospiral serovars in workers and those in cattle in their herds. A total of 52 herds was investigated, 25 of which were “high risk” where milkers had titres of 1:96 or greater, and 27 were case-controls where milkers had no detectable agglutinin titres at a minimum serum dilution of 1:24. The serological prevalence of titres to hardjo in cattle on “high risk” farms (76.5%) was significantly higher (P<0.05) than on the case-control farms (60.0%). The geometric mean titres of seropositive cattle on “high risk” farms were also significantly higher (P<0.01) than in the cattle from the case-control farms, especially in the younger cohorts. These findings suggest that there was active endemic hardjo infection in the two- to three-year-old cattle on the “high risk” farms. Titres to pomona were demonstrated in only 5.2% of the cattle from both types of farm. Workers with titres to pomona tended to be from farms on which stock, especially calves, were bought-in and pigs were kept. Conventional measures for protecting milkers from contact with infected urine appeared to be ineffective and it is concluded that prevention of leptospirosis in dairy farm workers can only be achieved by elimination of infection in the herd by vaccination of cattle.

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