Marine Mammal Care Center
Los Angeles

Science Corner - Seal Pox

If you’ve ever visited MMCC, you may have noticed animals with marble-sized bumps or lesions on their skin. The lesions are likely the result of seal pox, a DNA virus that can occur in captive, rehabilitating, and free-ranging seals and sea lions. Seal pox (genus Parapoxvirus) is a zoonotic disease, which means it can be transmitted between species. Because it is zoonotic, precautions to prevent exposure should be taken by humans handling and working in close contact with infected animals.

Like chicken pox in humans (chicken pox in humans is not caused by a poxvirus but a herpes virus Varicella zoster), there are several stages of clinical symptoms. Nodules appear 10-20 days after the initial exposure to the virus and dry up over the course of several weeks, however lesions may be visible for several months. Nodules are generally found on the head, neck, and thorax, but may appear on other parts of the body, including flippers and the mucous lining (mucosa) of the mouth. Studies indicate that animals with a prior rehabilitation history are at a higher risk of infection than animals in a rehabilitation facility for the first time.

During rehabilitation, it is standard procedure to isolate animals infected with the seal pox virus, but in stranding centers, especially when there are crowded conditions, it may be difficult to maintain the sanitary and quarantine conditions necessary to completely prevent the spread of the virus. In these situations, large numbers of animals can be affected but the infection is rarely fatal unless nodules on the snout, lips, and in the mouth interfere with eating. In most cases, no treatment is required, and the infection is allowed to run its course. Occasionally antibiotics are used if secondary bacterial infections occur.

After contact with infected animals, the pens, equipment, and personnel require scrub downs with a diluted bleach solution as a special precaution to destroy the virus.


Roess AA, Levine RS, Barth L, Monroe BP, Carroll DS, Damon IK, et al. Sealpox virus in marine mammal rehabilitation facilities, North America, 2007–2009 Emerg Infect Dis. 2011 Dec.

CRC Handbook of Marine Mammal Medicine: Health,   Disease, and Rehabilitation edited by Leslie A. Dierauf, Frances M.D. Gulland.

Nollens HH, Hernandez JA,  Jacobson ER, Haulena M, Gulland FM. Risk factors associated with development of poxvirus lesions in hospitalized California sea lions. J Am Vet Med Assoc. 2005;227:467–73.

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