Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA, USA
More than 35 Helicobacter spp. have been identified in a wide variety of terrestrial animals.3,4 All known helicobacters of humans and animals colonize the gastrointestinal tract.3-5 Helicobacter spp. are known to cause gastrointestinal disease in various hosts while others do not.3,4 In humans, Helicobacter pylori is a significant cause of peptic ulcer disease and gastric tumors.3 In terrestrial animals, Helicobacter spp. may cause gastritis or peptic ulcers, typhlocolitis, and hepatitis and can lead to gastrointestinal tumors in chronic infections.
A novel Helicobacter with the proposed name of Helicobacter cetorum sp. nov. has been isolated from wild and captive cetaceans.6 Our previous studies suggested that Helicobacter infection may play a role in the development of gastritis in cetaceans.6-8 It has been isolated from Atlantic and Pacific white-sided dolphins, Atlantic bottlenose dolphins, common dolphins, and a beluga whale.6-8 Clinical signs in infected captive cetaceans have been subclinical or included intermittent regurgitation, inappetence, weight loss and lethargy.
In addition to cetaceans, gastric ulcers have also been reported in other marine mammals. Gastric lesions in sea otters, seals and sea lions have been associated with parasitic infection and pollution, but in certain instances, the ulcers had no clearly defined etiologies.1,10,11 It was hypothesized that Helicobacter infection may play a role in the development of gastric lesions in sea otters (Enhydra lutris) and California sea lions (Zalophus californianus) based on our previously published observations in cetaceans, as well as clinical and pathologic findings of captive and wild animals by researchers and veterinarians.2,9 To date, at least two novel Helicobacter species have been identified from the gastric mucosa of stranded harp seals (Phoca vitulina) and the feces of California sea lions. Helicobacter infections have also been confirmed in stranded sea otters by PCR. These findings indicate that Helicobacter spp. are global in distribution in both terrestrial and aquatic hosts.
1. Bishop, L. 1979. Parasite-related lesions in a bearded seal, Erignathus barbatus. J Wildl Dis. 15:285–293.
2. Chechowitz-Miller, M. State of California Department of Fish and Game Marine Wildlife Veterinary Care and Research Center (personal communication).
3. Fox, J.G. 1997. The expanding genus of Helicobacter: pathogenic and zoonotic potential. Sem Gastroint. Dis. 8:124–141.
4. Fox, J.G. 2002. The non-H. pylori helicobacters: their expanding role in gastrointestinal and systemic diseases. Gut. 50:273–283.
5. Franklin, C.L., P.L. Gorelick, L.K. Riley, F.E. Dewhirst, R.S. Livingston, J.M. Ward, C.S. Beckwith, J.G. Fox. 2001. Helicobacter typhlonius sp. nov., a novel murine urease-negative Helicobacter species. J. Clin. Microbiol. 39:3920–3926.
6. Harper, C.M., Y. Feng, S. Xu, N.S. Taylor, M. Kinsel, F.E. Dewhirst, M. Greenwell, G. Levine, A. Rogers, J.G. Fox. 2002. Helicobacter cetorum sp. nov., a urease-positive Helicobacter species of dolphins and whales. (In progress.)
7. Harper C.M., S. Xu, Y. Feng, J.L. Dunn, N.S. Taylor, F.E. Dewhirst, J.G. Fox. 2002. Identification of novel Helicobacter spp. from a beluga whale. Appl Environ Microbiol. 68(4):2040–2043.
8. Harper C.M., C.A. Dangler, S. Xu, Y. Feng, Z. Shen, B. Sheppard, A. Stamper, F.E. Dewhirst, B.J. Paster, J.G. Fox. 2000. Isolation and characterization of a Helicobacter sp. from the gastric mucosa of dolphins, Lagenorhynchus acutus and Delphinus delphis. Appl. Environ. Microbiol. 66(11):4751–4757.
9. Hurley J.A., California State University, Moss Landing Marine Laboratories (personal communication).
10. Lipscomb T.P., R.K. Harris, R.B. Moeller, J.M. Pletcher, R.J. Haebler, B.E. Ballachey. 1993. Histopathologic lesions in sea otters exposed to crude oil. Vet Pathol. 30:1–11.
11. McClelland, G. 1980. Phocanema decipiens: pathology in seals. Exp. Parasitol. 49(3):405–419.