Salmonellae in avian wildlife in Norway from 1969 to 2000

Abstract

Postmortem records of wild-living birds in Norway with laboratory-confirmed findings of salmonella infection were summarized for the period from 1969 to 2000. Salmonella spp. were isolated from 470 birds belonging to 26 species. The salmonella-positive birds included 441 small passerines, 15 gulls, 5 waterfowl, 4 birds of prey, 3 doves, and 2 crows. The bullfinch (Pyrrhula pyrrhula) was by far the most frequently recorded species (54% of the cases). Salmonella enterica serover Typhimurium was recovered from all cases except from one hooded crow (Corvus corone), which yielded serovar Paratyphi-B var. Java. Variant O:4,12 comprised 96% (451 cases) of all serovar Typhimurium isolates, including all the passerines, while variant O:4,5,12 accounted for the remaining 4% (18 cases). The occurrence of salmonellae in small passerines showed a distinct seasonality, with a peak in February and March. Plasmid profile analysis of 346 isolates of serovar Typhimurium O:4,12 detected six profiles, of which two comprised 66 and 28% of the isolates, respectively. Phage typing of 52 randomly selected isolates of serovar Typhimurium O:4,12 from passerines detected four types: DT 40 (54%), U277 (35%), DT 99 (6%), and DT 110 (4%).

FIG. 1.

Number of wild-living birds from which Salmonella bacteria were isolated, by year, in Norway from 1969 to 2000.

FIG. 2.

Number of wild-living birds from which Salmonella bacteria were isolated, by month, in Norway from 1969 to 2000.

FIG. 3.

Plasmid profiles of serovar Typhimurium O:4,12 isolates from wild-living birds in Norway. The six plasmid profiles detected are shown in lanes 1 to 6. The size markers in lane 7 are standard plasmids (from top to bottom, 62.0, 35.8, 4.8, 3.4, 2.0, and 1.4 MDa).