Occurrence of Coxiella burnetii in bulk tank milk from northwestern Italy

Coxiella burnetii , the aetiologic agent of Q fever (Query fever), is an intracellular Gram-negative bacterium belonging to the family of Coxiellaceae (Drancourt and Raoult 2005). Infections by C burnetii involve a wide range of susceptible hosts, ranging from mammals to arthropods (Angelakis and Raoult 2010). Abortion, stillbirth and non-viable neonates are the main clinical signs of infection in sheep and goats, while metritis, infertility and, rarely abortion, are typical for cattle (Arricau-Bouvery and Rodolakis 2005). C burnetii can produce spore-like forms, which are easily spread by wind and are able to survive for several months in the environment; for this reason the inhalation of contaminated aerosol and/or dust is considered the primary route of infection (Arricau-Bouvery and Rodolakis 2005). The consumption of contaminated raw milk does not seem to represent an efficient route of disease transmission (Rodolakis and others 2007), however, bulk tank milk (BTM) is an important specimen for epidemiological survey on dairy herds. In fact, even if C burnetii can be excreted in milk by infected animals continuously or intermittently (Guatteo and others 2007), milk is the most frequent way of shedding in asymptomatic cows (Rodolakis and others 2007). Many investigations have been performed among ruminant farms in European countries (Paiba and others 1999, Agger and others 2010, McCaughey …