For many years, the Antarctic region has been isolated from human activity. However, there is little data available regarding endemic and exotic diseases. The purpose of this work was to determine the prevalence of Edwardsiella tarda in Antarctic wildlife, including birds, mammals and fish. During the summer of 2000 and 2002 in the Potter Peninsula, and during the summer of 2001 and 2003 in Hope Bay, a total of 1,805 faecal samples from Antarctic animals and 50 infertile eggs of Adelie penguins (Pygoscelis adeliae) were collected in order to isolate E. tarda. The classic Edwardsiella tarda was isolated from 281 (15.1%) of the 1,855 Antarctic wildlife samples. This is the first report of E. tarda isolation from southern giant petrels (Macronectes giganteus), brown skuas (Stercorarius lonnbergi), south polar skuas (Stercorarius maccormicki), kelp gulls (Larus dominicanus), greater sheathbills (Chionis albus), chinstrap penguins (Pygoscelis antarctica), eggs of Adelie penguins and Weddell seals (Leptonychotes weddelli). None of the evaluated animals showed clinical signs of disease. Our results suggest that E. tarda is a common bacterium amongst Antarctic birds and mammals.Facultad de Ciencias Veterinaria

Leotta, Gerardo Aníbal

Piñeyro Piñeiro, Pablo Enrique

Serena, María Soledad

Vigo, Germán Blas

Polar Biology

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Polar Biol (2009) 32:809–812DOI 10.1007/s00300-009-0610-9SHORT NOTEPrevalence of Edwardsiella tarda in Antarctic wildlifeGerardo A. Leotta · Pablo Piñeyro · Soledad Serena · Germán B. Vigo Received: 9 May 2008 / Revised: 26 February 2009 / Accepted: 3 March 2009 / Published online: 24 March 2009©  Springer-Verlag 2009Abstract For many years, the Antarctic region has beenisolated from human activity. However, there is little dataavailable regarding endemic and exotic diseases. Thepurpose of this work was to determine the prevalence ofEdwardsiella tarda in Antarctic wildlife, including birds,mammals and Wsh. During the summer of 2000 and 2002 inthe Potter Peninsula, and during the summer of 2001 and2003 in Hope Bay, a total of 1,805 faecal samples fromAntarctic animals and 50 infertile eggs of Adelie penguins(Pygoscelis adeliae) were collected in order to isolateE. tarda. The classic Edwardsiella tarda was isolatedfrom 281 (15.1%) of the 1,855 Antarctic wildlife samples.This is the Wrst report of E. tarda isolation from southerngiant petrels (Macronectes giganteus), brown skuas(Stercorarius lonnbergi), south polar skuas (Stercorariusmaccormicki), kelp gulls (Larus dominicanus), greatersheathbills (Chionis albus), chinstrap penguins (Pygoscelisantarctica), eggs of Adelie penguins and Weddell seals(Leptonychotes weddelli). None of the evaluated animalsshowed clinical signs of disease. Our results suggest thatE. tarda is a common bacterium amongst Antarctic birdsand mammals.IntroductionDue to the geographical isolation of the Antarctic region,the contact between the Antarctic fauna and bacterialpathogens is limited. However, the presence of humans hassigniWcantly increased as a result of tourism and scientiWcexpeditions (Bonnedahl et al. 2005). Given the limited dataavailable regarding endemic and exotic diseases, it is ratherdiYcult to determine the true origin of current diseases(Leotta et al. 2006a; Nievas et al. 2007). Edwardsiellatarda is considered a common inhabitant of the normalintestinal Xora in aquatic animals (White 1984); however,under certain circumstances, this bacterium can cause intes-tinal and extra-intestinal diseases and wound infections inreptiles, amphibians and terrestrial endotherms, includinghumans (Bockemuhl et al. 1971; Sakazaki and Tamura1992; Janda and Abbott 1993; Baya et al. 1997). This bac-terium is also considered a common opportunistic agent insick or injured marine wildlife (Coles et al. 1978). In Ant-arctic and sub-Antarctic animals, two cases associated withE. tarda have been reported. The Wrst case was in Rockhop-per penguins (Eudyptes crestatus) with chronic enteritis(Cook and Tappe 1985), and the second case, in an Adeliepenguin (Pygoscelis adeliae) with a subcutaneous clostrid-ial infection (Nievas et al. 2007). In addition, only tworeports describe E. tarda in Antarctic wildlife (Zunino et al.1985). However, the prevalence of E. tarda in AntarcticG. A. LeottaLaboratorio de Diagnóstico e Investigaciones Bacteriológicas, Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata, CC: 296, La Plata (1900), Buenos Aires, ArgentinaP. PiñeyroCátedra de Patología Especial, Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata, CC: 296, La Plata (1900), Buenos Aires, ArgentinaS. SerenaCátedra de Virología, Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata, CC: 296, La Plata (1900), Buenos Aires, ArgentinaG. B. Vigo (&)Cátedra de Microbiología, Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata, CC: 296, La Plata (1900), Buenos Aires, Argentinae-mail: gvigo@fcv.unlp.edu.ar123810 Polar Biol (2009) 32:809–812wildlife has never been reported. The purpose of this workwas to determine the prevalence of Edwardsiella tarda inAntarctic wildlife, including birds, mammals and Wsh.MethodsSampling was carried out in Potter Peninsula, located onKing George Island, South Shetland Islands (62°159S,58°369W), and in the Hope Bay area, located on the tip ofthe Antarctic Peninsula (63°249S, 56°599W). During thespring and summer seasons, these are breeding areas forsome seabirds (Hahn et al. 1998; Leotta et al. 2006a), andoccasionally for Antarctic sea mammals. One of the mainWsh found in these regions is Nothotenidae, which is one ofthe food sources of both mammals and birds. A total of1,855 samples were collected from Antarctic animals in thesummer of 2000 and 2002 (Potter Peninsula), and 2001 and2003 (Hope Bay). Non-probabilistic sampling was carriedout in animals that were separated from their coloniesfor mere convenience. Breeding areas for brown skuas(Stercorarius lonnbergi), south polar skuas (Stercorariusmaccormicki), kelp gulls (Larus dominicanus), south giantpetrels (Macronectes giganteus), Adelie penguins, gentoopenguins (Pygoscelis papua), chinstrap penguins (Pygosc-elis antarctica), and greater sheathbills (Chionis albus)were identiWed. The population was calculated using a cen-sus carried out by Hahn et al. (1998) and Leotta et al.(2006a). A total of 1,622 seabirds were captured, clinicallyevaluated by experienced veterinarians, and sampled withcloacal swabs, which were conserved on Stuart transportmedia (Difco Laboratories Incorporated, Cambridge, UK)at 4°C. Fifty infertile eggs of Adelie penguins were col-lected from the nest after the incubation period, they werewashed with distilled water and neutral detergent, dried andimmersed into alcohol 70° for 1 h. Then they were driedand the content was streaked onto hektoen agar (Difco) andincubated at 37°C for 48 h. In addition, 161 Antarcticfur seals (Arctocephalus gazella) and Weddell seals(Leptonychotes weddelli) were observed but not captured,and immediately after defecation an aliquot of fresh faeceswas collected in sterile bags (Nasco’s Whirl-pak, NetworkInternational Technologies, Buenos Aires, Argentina) andconserved at 4°C. Finally, a total of 22 Wshes (Nothoteniacoriiceps) were captured, sacriWced, necropsied, and an ali-quot of intestinal contents was collected in sterile bags(Nasco’s Whirl-pak) and conserved at 4°C. All samples ofbirds, mammals and Wsh were processed between 2 and12 h after being collected. Each sample was plated directlyonto hektoen enteric agar (Difco), and incubated at 37°Cfor 48 h. The suspected blue-green colonies with blackcentres were subcultured onto trypticase soy agar (Difco)and incubated at 37°C for 24 h. Pure colonies were subse-quently inoculated into brain heart infusion broth (Difco)with 30% of glycerol and stored at ¡20°C. All suspectedE. tarda colonies were subjected to a complete phenotypiccharacterisation. The Gram stain of the isolates was deter-mined, and the following biochemical tests were carried outaccording to the manufacturer’s directions: catalase (WacoPure Chemical Industries, Osaka, Japan), oxidase (Labora-torios Britania, Buenos Aires, Argentina), b-galactosidase(Laboratorios Britania), indole (Laboratorios Britania),methyl red (Difco), Voges-Proskauer (Difco), citrate(Difco), lysine (Difco), urea (Difco), malonate (Difco),ornitine (Difco), sulfhydric acid (tri sugar iron, Difco),glucose (ICN Biomedicals, Aurora, Ohio, USA), lactose(ICN), dulcitol (ICN), salicine (ICN), raYnose (ICN), sor-bitol (ICN), arabinose (ICN), maltose (ICN), xylose (ICN),trehalose (ICN), and sucrose (ICN), according to themethod described by Koneman et al. (1999). A statisticalanalysis of data was performed using Statgraphics Centu-rion XV version 15.2.05 (StatPoint Inc., Herdon, Virginia,USA).ResultsThe classic Edwardsiella tarda was isolated from 281(15.1%) of 1,855 Antarctic wildlife samples obtained fromsouthern giant petrels, brown skuas, greater sheathbills,Adelie penguins, gentoo penguins and chinstrap penguinsfrom Potter Peninsula in 2000 and 2002. E. tarda could notbe isolated in 54 faecal samples from Antarctic fur seals, 22samples from Wsh and 32 samples from south polar skuas in2002. E. tarda was isolated from brown skuas, kelp gulls,greater sheathbills, Adelie penguins and their eggs, chin-strap penguins and Weddell seals from Hope Bay in 2001and 2003. However, in the summer of 2003, E. tarda couldnot be isolated from the cloacal samples from 22 gentoopenguins. In all the birds sampled in both places, no clinicalsigns of disease were observed. In 15 Wshes, no pathologi-cal lesions were observed, but in the intestine from sevenWshes, endoparasites were observed. Animal species,seasons, geographical regions, identiWcation of Antarcticwildlife population sampled, and the prevalence of E. tardaare shown in Table 1. As a result of the non-probabilisticsampling method used, the positive rate observed amongstseasons, areas and species did not exhibit a normal distribu-tion. There were no statistical diVerences amongst seasonsand/or geographic areas of the positive samples obtained(P = 0.24, Kruskal Wallis test) (P = 0.07, Kolmogorov–Smirnov test). Due to the lack of positive results amongstthe Wsh evaluated, only the diVerences amongst the meanof positive results in birds and mammals were analysed,where no statistical diVerences were observed (P = 0.93,Kolmogorov–Smirnov test).123Polar Biol (2009) 32:809–812 811DiscussionIn this study we isolated E. tarda in 15.1% of Antarcticwildlife animals sampled in two places of Antarctica,Hope Bay and Potter Peninsula. We considered thatE. tarda is a common bacterium in the faeces of Antarcticbirds and mammals, because no signiWcant diVerenceswere found with regard to the areas and seasons investi-gated. This is supported by the fact that there are no sig-niWcant diVerences in the distribution of positive ratesobtained within the species evaluated. However, E. tardawas described as an opportunistic bacterial pathogen andhas been commonly isolated from diVerent healthy, sickand moribund Wsh, birds and reptiles in several ecosys-tems around the world (White and Simpson 1973; Trustand Bartlett 1974; Baya et al. 1997). Antarctic birds andmammals eat Wsh, particularly Nothotenia coriiceps. Weconsidered that the trophic chain could be one of the linksin E. tarda transmission. However, none of the 22N. coriiceps samples was positive for E. tarda. The nega-tive results, though inconclusive, could be due to thesmall number of Wsh sampled.Several enteropathogens such as Campylobacter lari,Campylobacter jejuni, Salmonella spp., and enteropatho-genic Escherichia coli, were isolated from Antarctic animals(Oelke and Steiniger 1973; Bonnedahl et al. 2005; Leottaet al. 2006a, b). The known prevalence of E. tarda inAntarctic animals is an important precedent for the futurecontrol and surveillance of populations of mammals, birdsand Wshes, since this enteropathogen could cause diseasesin these animals, which could be an indicator of the healthof the ecosystem.This is the Wrst report of E. tarda isolation from southerngiant petrels, skuas, kelp gulls, greater sheathbills, chin-strap penguins, eggs of Adelie penguins, and Weddell seals.However, further investigations are necessary in order todetermine the role of E. tarda as a pathogen of Antarcticwildlife fauna.Acknowledgments The authors would like to thank Instituto Antár-tico Argentino and Departamento de Biología, Dirección Nacional delAntártico, for providing support for Weld work in Antarctica, especiallyto N. R. Coria. We are grateful to M. Pérez Cometto and D. Montaltifor their Weld collaboration. We also thank Lucía Isturiz and Paul Flynnfor their English revision of the manuscript.Table 1 Antarctic wildlife species, geographical region, animal population, season, number of analyzed samples and prevalence of E. tardaSpecies Geographical regionPopulation Year Samples 95% CI N Positive PrevalenceSouthern giant petrels Macronectes giganteusPotter Peninsula 150 2000 90 20 22.2 13.07–31.362002 48 16 33.3 18.85–47.71Brown skuas Stercorarius lonnbergi Hope Bay 75 2001 14 2 14.3 1.77–42.81Hope Bay 75 2003 36 10 27.8 11.75–43.79South polar skuas Stercorarius maccormickiPotter Peninsula 166 2000 66 9 13.6 4.6–22.67Potter Peninsula 166 2002 32 0 0.0 –Kelp gulls Larus dominicanus Hope Bay 213 2001 50 18 36.0 21.69–50.32003 54 23 42.6 28.47–56.7Greater sheathbills Chionis albus Hope Bay 87 2001 50 19 38 23.54–52.45Potter Peninsula 12 2002 6 4 66.6 22.27–95.67Hope Bay 87 2003 22 4 18.2 5.18–40.28Adelie penguins Pygoscelis adeliae Potter Peninsula 29,108 2000 50 2 4.0 0.48–13.71Hope Bay 247,218 2001 755 88 11.7 9.3–14.012003 144 14 9.7 4.53–14.9Adelie penguin eggs Hope Bay 125,000 2001 50 2 4.0 0.48–13.71Gentoo penguins Pygoscelis papua Potter Peninsula 4650 2000 50 1 2.0 0.05–10.64Hope Bay 690 2001 100 16 16.0 8.31–23.68Potter Peninsula 4650 2002 33 5 15.1 15.15–31.89Hope Bay 690 2003 22 0 0.0 –Chinstrap penguins Pygoscelis antarctica Potter Peninsula 530 2002 39 5 12.8 4.29–27.43Antarctic fur seals Arctocephalus gazella Potter Peninsula Unknown 2002 32 0 0.0 –Weddell seals Leptonychotes weddelli Hope Bay Unknown 2003 90 23 25.5 15.98–35.12Nothotenia coriiceps Potter Peninsula Unknown 2002 22 0 0.0 –Total 2000–2003 1855 281 15.1 13.49–16.8123812 Polar Biol (2009) 32:809–812ReferencesBaya AM, Romalde JL, Green DE, Navarro RB, Evans J, May EB,Toranzo AE (1997) Edwardsiellosis in wild striped bass from theChesapeake Bay. 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Prevalence of Edwardsiella tarda in Antarctic wildlife

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Prevalence of Edwardsiella tarda in Antarctic wildlife

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