Leptospirosis in three workers on a dairy farm with unvaccinated cattle

We report a one-health investigation of three cases of leptospirosis on a dairy farm with unvaccinated cattle in New Zealand. The cases are discussed in the context of diagnostics, risk factors, persistence of symptoms and outbreak mitigation measures.

Clinical and laboratory records from the human cases were reviewed and serological and molecular investigations were conducted into the Leptospira status of cattle and pigs on the farm.

Cases presented early in their illness and all three were confirmed within seven days of onset of symptoms by urine PCR and within 18 days by convalescent MAT (two Hardjo, one Pomona). Cattle and pigs had serological evidence of recent infection with Hardjo/Pomona and Pomona/Copenhageni respectively. Pigs were slaughtered and cattle were vaccinated. Post-exposure prophylaxis was given to staff in-contact with the milking herd until the herd had antibiotic treatment at drying-off (approximately four months after the initial case).

The utility of PCR testing for Leptospira DNA as both an early and rapid test for leptospirosis was demonstrated. Two of three cases reported persistence of symptoms at least six months after the acute episode and one of these remains unable to work. Risk mitigation measures such as post-exposure prophylaxis, animal vaccination, heightened clinical suspicion of leptospirosis and recognition of context specific risk factors (eg, effluent spreading) demonstrate the value of medical and veterinary experts working together.