Can animals catch Legionnaires’ disease?

Animal owners are often asking if their animals can catch Legionnaires’ disease. In a scientific paper released in 1997 by MASSIMO FABBI,  MADDALENA CASTELLANI PASTORIS, EUGENIO SCANZIANI, SIMONE MAGNINO, and LUIGI DI MATTEO, entitled “Epidemiological and Environmental Investigations of Legionella pneumophila Infection in Cattle and Case Report of Fatal Pneumonia in a Calf” they stated:

“However, the widespread distribution of legionellae is in contrast to a somewhat surprising lack of clinical reports of L. pneumophila infection in animals, which has prompted several investigators to assess the susceptibilities of different animal species to Legionella infection. Investigations have been carried out with both domestic animals (cattle, horses, swine, sheep, goats, dogs, and rabbits) and wild animals (antelopes, water buffaloes, camels, and pigeons) in order to detect a serological evidence of infection, yet so far the results have not been conclusive. Among all animals investigated, horses yielded the highest prevalence of antibodies to Legionella, even though the experimental infection of this species only prompted a marked serological response without clear signs of clinical illness”

They further stated “There is a strong evidence that the calf that was the object of our studies died of a severe pneumonia due to a Legionella infection” however they went on to conclude “Our data suggest that Legionella disease in cattle should be considered an uncommon event. Predisposing factors such as poor hygiene, bad management, and insufficient and/or unbalanced feeding seem to be important in the occurrence of the disease. When diagnosing severe pneumonia’s in cattle, it would therefore be advisable to perform investigations aimed at the detection of Legionella. Legionellosis in cattle should be regarded as a minor hazard to human health, since cattle probably act as accidental hosts for legionellae, much the same as humans.”

It therefore seems that whilst cows can, in very rare cases, catch Legionnaires’ disease there is no evidence of other animals catching the illness.

If you need help or advice on Legionnaires’ disease risk management in humans then please contact Collaton Consultancy Limited who are leading experts on Legionella risk management. Email us on, or visit our websites: and

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