EPIDEMIOLOGIC AND ENVIRONMENTAL INVESTIGATIONS OF LEGIONELLA-PNEUMOPHILA INFECTION IN CATTLE AND CASE-REPORT OF FATAL PNEUMONIA IN A CALF

A fatal pneumonia due to Legionella pneumophila was diagnosed in a you ng calf reared in a daily herd located in northern Italy. Clinical sym ptoms consisted of watery diarrhea, hyperthermia, anorexia, and severe dyspnea, The pathological and histological findings were very similar to those observed in human legionellosis, Legionella pneumophila sero group 1 (SG1) and SG10 were isolated from the calfs lung, and L. pneum ophila SG1 was isolated from the calfs liver. L. pneumophila SG1 was a lso demonstrated in the lung tissue by immunofluorescence and immunohi stochemical examinations, Nine of 10 L. pneumophila SG1 isolates belon ged to the Olda subtype, and 1 belonged to the Camperdown subtype. A v ery low prevalence of antibodies to Legionella was detected in cows an d calves reared in the same herd. Cultures of aqueous sediment of an o ld electric water heater which supplied hot water for the feeding of t he calves yielded L. pneumophila SG1, Four of the colonies tested belo nged to the Olda subtype. Ten clinical and four environmental isolates were examined for the presence of plasmids, Nine of them were also ex amined by pulsed-field gel electrophoresis assay, and the same pattern s were found for L. pneumophila SG1 Olda strains isolated from the cal f and from the electric heater. This is the first report of a document ed case of a naturally occurring Legionella pneumonia in an animal. Ca ttle probably act as accidental hosts for legionellae, much the same a s humans.