Salmonella enteritidis in Antarctica: zoonosis in man or humanosis in penguins?

• Published in: The Lancet
• Main Authors: Olsen, B., Bergstrom, S., McCafferty, D., Sellin, M., Wistrom, J.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: The Lancet Publishing Group 1996
• Subjects: Antarctic; Austral; Bird Island; The Antarctic; Antarc*; Antarctic Fur Seals; Antarctica; Gentoo penguin; Pygoscelis papua
• Online Access: http://eprints.gla.ac.uk/49028/; https://doi.org/10.1016/S0140-6736(05)65807-2

Salmonella enteritidis has emerged as one of the most prevalent salmonella serotypes world-wide. Birds are the main reservoir of this pathogen and human beings are most commonly infected after eating contaminated eggs or egg products from domestic hens.1 In the Austral summer 1995–96 we sampled faecal material from various species of penguins, albatrosses, and from Antarctic fur seals on Bird Island, South Georgia, in the South Atlantic. S enteritidis phage type 4 was isolated from one Gentoo penguin (Pygoscelis papua). This phage type accounts for approximately 80% of clinical S enteritidis isolates in the western world and has in recent years been associated with numerous food-borne outbreaks of salmonellosis.2 To investigate the possibility of a clonal spread of 5 enteritidis from other continents to Antarctica, we compared the genotypic pattern of that of other S enteritidis phage type 4 isolates from birds and human beings in Europe, North Africa, and South America. By restriction-enzyme digestion of the genome and subsequent pulse-field gel electrophoresis (PFGE)3 we detected a unique PFGE pattern in the penguin isolate, leaving no guidance to the route of transmission or to the origin. However, clonal spread within Europe was evident since all European isolates exhibited identical PFGE pattern, whereas all other isolates originated from separate clones. Antibiograms using a standard set of antibiotics did not reveal acquired resistance in any of the isolates. Because only one of the 30 penguin samples proved positive we believe that salmonella is either low in abundance or is not indigenous to Gentoo penguins at Bird Island. We believe there are three possible routes of introduction of 5 enteritidis to Antarctica. Bacteria may have been introduced by human carriers, by contaminated food items, or by infected birds. Direct spread of salmonella could occur from contaminated food or sewage from a limited number of land-based operations or from the discharge of this material from ships and fishing vessels which frequently visit waters around South Georgia. Several species of albatross which breed at South Georgia have foraging ranges which extend as far as the oceans surrounding South America. These together with species which migrate from the northern hemisphere have the potential to transmit infected material to the Antarctic. This transequatorial transport has previously been described with tick-associated viruses and Borrelia burgdorferi sp.4 Usually the transmission of zoonoses is one-way from the animal to human beings. However the finding of S enteritidis phage type 4 in the penguin population at South Georgia may indicate a bi-directional route. The possibility that man could introduce such an organism in Antarctica may determine environmental protocols for waste disposal. The prevalence of salmonella in the Antarctic and any possible impact on its inhabitants needs to be further investigated.