Marine Mammal Zoonotic Viruses
 
  1. San Miguel Seal Lion virus (calicivirus)
  2. Influenza A (orthomyxovirus)
  3. Sealpox (parapoxvirus)

San Miguel Sea Lion Virus (SMSV)

Smith, in 1998, reported the first confirmed human case of SMSV after isolating the virus from blisters on the hands and feet of a laboratory worker with systemic illness (Smith, Berry et al. 1998).

Pathogen
A calicivirus, San Miguel Sea Lion Virus is molecularly identical to vesicular exanthema of swine first identified in California in the 1920s.

Clinical signs in marine mammals
SMSV causes vesicular lesions at mucocutaneous junctions and on the ventral surface of flippers (Smith, Skilling et al. 1998).

Clinical disease in humans
There have been very few suspected cases of human infections with SMSV. Lesions in humans appear to be similar to those seen in marine mammals. There is no treatment and the disease is self-limiting (Smith, Berry et al. 1998).

Back to Top

Influenza A 
An investigator at the New England Aquarium developed a severe conjunctivitis subsequent to having a harbor seal (Phoca vitulina) contaminate the eye with a sneeze.  Swabs taken of the inflamed eye two days post-contamination showed exposure to Influenza A  (Webster, Geraci et al. 1981).

Pathogen
Influenza A is an Orthomyxovirus. Influenza A has a natural reservoir in the wild bird population and can infect a wild range of hosts.
Note: Influenza B, thought to be primarily a human pathogen, was identified using reverse transcriptase polymerase chain reaction from a naturally infected harbor seal (Phoca vitulina) (Osterhaus, Rimmelzwaan et al. 2000). Transmission of Influenza B from animals to humans has not been documented.

Clinical disease in marine mammals
Influenza A acts in synergy with Mycoplasma infections causing pneumonia in seals. The respiratory infections have been a major factor in mass mortality and stranding in harbor seal populations (Webster, Geraci et al. 1981).

Clinical disease in humans
In the case mentioned above, contamination of the eye with Influenza A caused a painful purulent conjunctivitis, the onset of which was approximately 48 hrs after exposure. No treatment was attempted; the inflammation resolved in about 5 days.

Back to Top

Sealpox
Two researchers were infected while working with grey seals (Halichoerus grypus) at the University of Guelph and developed lesions on their fingers. Skin scrapings of the lesions reveal viral particles that were microscopically identical to those identified from the grey seals' lesions (Hicks and Worthy 1987).

Pathogen
Sealpox is classified as a Parapoxvirus. Other related viruses include orf in sheep and bovine papular stomatitis in cattle.

Clinical disease in marine mammals
Causes singular to coalescing nodules on the head and neck and ventral surfaces of the flippers of seals and sea lions. Histopathologically, the lesions are hyperkeratotic and parakeratotic. The nodules will often ulcerate after 2 weeks but will resolve in about 4 weeks (Hicks and Worthy 1987).

Clinical symptoms in humans
The lesions in humans have been described as "milker's nodules". They are found most commonly on digits and are raised edematous and erythematous nodules. They have a histological appearance consistent with parapox lesions (i.e. hyperkeratosis/parakeratotic).  There is no treatment. Lesions should resolve on their own.

Back to Top

Home ] [ Viruses ] Bacteria ] Fungi ] [References]