Is there a risk for people who work with marine mammals?

                                                            Photo by Joseph Gaydos

Necropsy of a beached fin whale

Many species of marine mammals can be infected with, or be healthy carriers of, bacterial, fungal and viral organisms which are known zoonotic pathogens. The risk of acquiring diseases from marine mammals differs as humans interact with marine mammals under different circumstances, such as commercial fishing, subsistence harvesting, scientific activities, wildlife rehabilitation, and animal training. Epidemics of food- borne illnesses such salmonellosis, trichinellosis and toxoplasmosis have been reported in native peoples of arctic and Australasian regions who harvest marine mammals as part of a traditional diet (Tryland 2000; Cawthorn 1997); however, the risk of acquiring diseases by scientists, wildlife rehabilitators, and animal trainers is not well understood.

Zoonotic disease transmission as a result of occupational contact between marine mammals and humans has been infrequently reported in the scientific literature. The most commonly reported disease is "seal finger". Hundreds of cases of this ailment have been reported in the scientific literature from fishermen and whalers (Hartley and Pitcher 2002), but there are few case reports of the disease occurring in scientists and rehabilitators. This syndrome was once thought to be caused by the bacteria Erysipelothrix rhusiopathiae but is now thought to be caused by Mycoplasma spp. This bacteria-like organism is carried in the mouth and on the skin of marine mammals (primarily seals and sea lions) and can infect humans by entering the body through breaks in the skin. The resulting infection causes a painful dermal abscess.

Other reports of marine mammal workers acquiring diseases from marine mammals include:    

Calicivirus (San Miguel Seal Lion virus) from northern fur seals (Callorhinus ursinus).
Reference: Smith, Berry et al. 1998

Blastomyces dermatitidis from a bottlenose dolphin (Tursiops truncatus).  
Reference: Cates, Kaufman et al. 1986

Erysipelothrix rhusiopathiae from a beached pilot whale (Globicephala melaena).
Reference: Chastel, Masure et al. 1975

Influenza A virus from harbor seals (Phoca vitulina)
Reference: Webster, Geraci et al. 1981

Leptospira spp. from California sea lion (Zalophus californianus) carcasses. 
Reference: Smith, Vedros et al. 1978

Mycobacterium bovis from a New Zealand fur seal (Arctocephalus forsteri). 
Reference: Thompson, Cousins et al. 1993 

Mycobacterium marinum from a bottlenose dolphin (Tursiops truncatus).
Reference: Flowers 1970

Sealpox virus from gray seals (Halichoerus grypus). 
Reference: Hicks and Worthy 1987


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