A total of 100 free-living urban pigeons (Columba livia) were captured in the city of Santiago, Chile, in order to evaluate, for the ® rst time, their health status. Negligible antibody titres (1 to 3 log2) were detected in 22% of the birds against a strain of the paramyxovirus (PMV) serotype 1. No pigeons had antibodies against PMV serotype 7 and avian in¯uenza. Salmonella sp. belonging to serogroups B and D were isolated from the intestinal tract of three pigeons (3%). The protozoa Haemoproteus columbae, Plasmodium sp., and Leucocytozoon sp. were not detected in any pigeons. Trichomonas gallinae was detected in 11%, without observation of either clinical signs or gross pathological changes at necropsy. Sixty-seven percent of the birds showed the presence of the chewing lice Columbicola columbae and Campanulotes bidentatus compar, and 1% harboured the mite Laminosioptes cysticola. Seven species of nematodes were identi® ed. The frequency at which each species was detected was; Tetrameres sp. (14%), Capillaria annulata (1%), Capillaria columbae (11%), Capillaria obsignata (1%), Ascaridia columbae (5%), Dispharynx spiralis (2%), and Gongylonema ingluvicola (2%). The class Cestoda, found in one pigeon, was represented by the species Aporina delafondi. No trematodes were detected in the sampled birds.

Three different lyric bacteriophages (BPs) were isolated from the sewage system of commercial chicken flocks and used to reduce Salmonella Enteritidis (SE) colonization from experimental chickens. Ten-day-old chickens were challenged with 9.6 x 10(5) colony-forming units (CFU)/ml of a SE strain and treated by coarse spray or drinking water with a cocktail of the three phages at a multiplicity of infection (MO1) of 10(3) plaque-forming units (PFU) 24 hr prior to SE challenge. Chickens were euthanatized at day 20 of age for individual SE detection, quantitative bacteriology, and phage isolation from the intestine and from a pool of organs. SE detection was performed by both bacteriologic culture and genome detection by polymerase chain reaction (PCR). Qualitative bacteriology showed that aerosol-spray delivery of BPs significantly reduced the incidence of SE infection in the chicken group (P = 0.0084) to 72.7% as compared with the control group (100%). In addition, SE counts showed that phage delivery both by coarse spray and drinking water reduced the intestinal SE colonization (P < 0.01; P < 0.05, respectively). BPs were isolated at 10 days postinfection from the intestine and from pools of organs from BP-treated chickens. We conclude that the phage treatment, either by aerosol spray or drinking water, may be a plausible alternative to antibiotics for the reduction of Salmonella infection in poultry.

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Fecal samples from slaughtered cattle were studred for enterohaemorrhagic E&vichia co/i (EHEC) by DNA hybridization with biotin-labelled DNA probes specific for the EHEC virulence plasmid, Shigalike toxin I (SLT I), Shiga-like toxin I1 (SLT 11) and eae gene. Among 136 animals analysed, 47 (34.5%) were found to carry EHEC. The cytotoxic genotypes observed for EHEC strains were: 60.4% SLT I, 12.5% SLT I1 and 10.4% SLT I+SLT 11; 16.7% resulted SLT I and SLT I1 negative. A total of 14 out of 48EHEC strains (29.2%) hybridzed with a fimbrial probe and 14 of 48 strains with an e m probe. An important number of strains (18 out of 48) belonged to serogroups 0157,026 and 0 1 11, serogroups also commonly isolated from haemolytic uremic syndrome cascs in Chile. While EHEC isolates from the same animal were usually of the same serogroup, one animal was found to carry two EHEC strains of drfferent serogroups. A total of 50' Yn of EHEC strains were sorbitol negative, irrespective of the 0 serogroup or EHEC genotypic profile. Results obtained in this study strongly suggest that cattle in Chile are a reservoir of EHEC associated with disease in humans.

To determine clonal relationship among Chilean enterohemorrhagicEscherichia coli (EHEC) strains from different sources (clinical infections, animal reservoirs, and food), 54 EHEC isolates (44 of E. coli O157, 5 of E. coli O111, and 5 of E. coli O26) were characterized for virulence genes by colony blot hybridization and by pulsed-field gel electrophoresis (PFGE). By colony blotting, 12 different genotypes were identified among the 44 E. coli O157 isolates analyzed, of which the genetic profile stx 1 + stx 2 + hly+eae + was the most prevalent. All human O157 strains that were associated with sporadic cases of hemolytic-uremic syndrome (HUS) carried both the stx 1 andstx 2 toxin-encoding genes and wereeaeA positive. Only 9 of 13 isolates from human controls were stx 1 + stx 2 +, and 8 carried theeaeA gene. Comparison of profiles obtained by PFGE ofXbaI-digested genomic DNA showed a great diversity among the E. coli O157 isolates, with 37 different profiles among 39 isolates analyzed. Cluster analysis of PFGE profiles showed a wide distribution of clinical isolates obtained from HUS cases and asymptomatic individuals and a clonal relationship among O157 isolates obtained from HUS cases and pigs. Analysis of virulence genes showed that a correlation exists among strains with the genotypestx 1 + stx 2 + eae +and pathogenic potential. A larger difference in the PFGE restriction patterns was observed among the EHEC strains of serogroups O26 and O111. These results indicate that several different EHEC clones circulate in Chile and suggest that pigs are an important animal reservoir for human infections by EHEC. Guidelines have been proposed for better practices in the slaughter of animals in Chile.