Salmonella bongori 48:z35:– in Migratory Birds, Italy

To the Editor: Serovars of Salmonella, other than subspecies enterica, are primarily associated with cold-blooded animals and infrequently colonize the intestines of warm-blooded animals. Strains of S. bongori, in particular, are rarely isolated from human patients (1,2). However , during 1984–2004, 27 strains of S. bongori with the antigenic formula 48:z 35 :– were identifi ed from 2 epi-and from sporadic cases of acute enteritis that occurred in several cities in Sicily. Almost all cases involved children 1 month to 3 years of age (3). By 2006, 8 additional isolates of the same serovar had been collected in southern Italy from the following sources: 1) a healthy human carrier; 2) 3 warm-blooded animals (2 apparently healthy pigeons and a dog with diarrhea); 3) 2 food products (soft cheese and the shell of a hen's egg); and 4) urban wastewater (3). No cases of human infections caused by S. bongori 48:z 35 :– have been reported in countries other than Italy. Except for the original strain isolated from a lizard in Chad in 1966 (4), the only recorded isolates of this serovar are 4 isolates from foodstuffs recovered in England in 1985 (M.Y. Popoff, pers. comm.). Pulsed-fi eld gel electrophoresis (PFGE) analysis of XbaI-digested DNA of the 35 isolates obtained from Sicily showed identical or similar pro-fi les that differed from each other by 2–5 bands (>79% similarity), except for the profi le obtained from the soft cheese isolate (<40% similarity) (3). Thus, all but one of the isolates could be considered closely or at least likely related to the oldest profi le characterizing the putative ancestor clone. Until now, the rare S. bongori 48:z 35 :–, an apparent epidemiologic peculiarity of Sicily, could not have been traced to a well-defi ned source. Indeed, in past years, many infrequently isolated and new serovars of Salmonella have been identifi ed in Sic-ily from wild reptiles, but S. bongori 48:z 35 :– has never been isolated from these animals (5). Moreover, whether pigeons that live in urban areas have epidemiologic importance as sources of infection is questionable, because of the apparently exclusive infection of infants in the fi rst months of life. The role of migratory birds has not previously been assessed. To determine the prevalence of birdborne pathogens in the migratory bird fauna of the Mediterranean basin , we conducted a study in October 2006, during ringing (banding) activity at the station …