Abstract

As part of national monitoring programmes in Germany living and dead marine mammals from the North and Baltic Seas are investigated for their health status. Furthermore, seals rescued in the seal station Friedrichskoog are examined constantly during their stay in the station. Investigations include blood status as well as pathological, microbiological, parasitological, serological and chemical tests. According to reports about Brucella infections in seas mammals, bacteriological and serological investigations in animals found in Germany were extended also to Brucella bacteria. Between 1997 and 2000 bacteriological investigations were performed on 165 common seals (Phoca vitulina), 80 harbour porpoises (Phocoena phocoena), 11 grey seals (Halichoerus grypus) and 3 other marine mammals. The organs examined were liver, spleen, kidney, lung, intestine, stomach, lung lymph nodes, mesenterial lymph nodes and others. For cultivation Brain-Heart-Infusion-agar and Brucella-agar were incubated at 37° Celsius in a CO2-enriched atmosphere. Furthermore, serum samples of 155 harbour seals were tested for Brucella-antibodies using a tube agglutination test with a stardardised Brucella abortus antigen.

The investigations revealed that out of 259 animals 32 Brucella strains from a total of 20 animals were isolated. The majority of the strains were found in the lung of seals. 30 of the 155 animals (19,4%) tested serologically had antibodies ranging between 1:20 and 1:10240. So far, the Brucella isolates have been identified as Brucella maris but specific molecular biological investigations are currently under process.

To our knowledge, this is the first report about the evidence of Brucella bacteria in marine mammals from German waters. According to the pathological findings, no typical lesions were associated with the evidence of Brucella sp. in this material. Little is known about the pathogenic potential of Brucella maris, in particular in humans, therefore special precautions should be taken when handling living or dead marine mammals