Marine Mammal Preventative Medicine

Question 1

How are zoonoses transmitted from marine mammals to people?

Answer 1

Modes of Transmission:

• Direct contact (skin to skin or exposure to bodily fluids) and indirect contact (contaminated surfaces or environment). Survey of marine mammal workers – 50% reported an injury, while 20% reported skin reaction or rash.
• Consumption – 87 marine mammal species consumed in 54 countries. Can include normal microbiota. Also includes contamination (i.e., from fecal sources) including clostridium and E coli from intestinal contents. Can occur from translocation due to postmortem timing or from projectiles used in capture.
  
  • In Norway meat industry test for fecal contamination (coliforms, E coli, streptococci, enterococci, clostridia, fecal bacteriophages. Also, salmonella, yersinia entercoliticia and listera monocytogenes. Often served as salted/dried products.

Question 2

What are five marine mammal viruses that are zoonotic?

Answer 2

Viral Zoonoses:

• Poxvirus – Sealpox, affects the skin and mucosal membranes of seals can be transmitted through skin abrasions or wounds. Begins as red skin (macule) then progresses into a vesicle or pustule 2-3 weeks after contact (usually face or hands). Can also get fever and swollen lymph nodes. Seen in wild seals and those in rehab centers, possibly from stress.
• Calicivirus – detected in seals, cetaceans, and polar bears.
  
  • San Miguel sea lion virus (SMSV) – vesicular lesions of the skin and oral mucosa of California sea lions, causative agent of vesicular exanthema of swine (VES). Not noted in surveys of Alaskan natives handling SMSV infected seals, but one report of a laboratory worker with SMSV-5 with lesions on the palms, fingers, and toes.
• Influenza
  
  • Seals – clinical signs of respiratory distress, pneumonia, lethargy, incoordination, nasal discharge and ulceration of the skin and oral mucosa.
    
    • Mass strandings with pneumonia as predominant finding – four workers developed purulent conjunctivitis with periorbital swelling although no firm association was established.
    • H3N8 from north American waterfowl confirmed in stranded harbor seals with pneumonia and skin ulcerations.
    • H1N1 detected in elephant seals
    • Influenza B isolated from naturally infected harbor seal
  • Pilot Whales – Influenza A involved in two mass strandings
• Rabies virus
  
  • Seal found far from breathing hole with wounds on dorsum. Developed edematous skin lesion, confusion and aggression and was euthanized.
  • Polar bear with posterior paralysis
• Norovirus
  
  • Causes gastroenteritis in humans. Found in feces of California sea lions and harbor porpoise. In screenings, 10% of harbor porpoises contained norovirus (HPNV – harbor porpoise norovirus).

Question 3

List five bacterial infections of marine mammals that are potentially zoonotic.

Answer 3

• Seal Finger and Mycoplasma spp.
  
  • Also known as speck finger, sealers finger or blubber finger – this is caused by one or more types of mycoplasma (M. phocacerebrale). M. Phocidae and M. phocarhinis isolated from harbor seals with pneumonia.
  • May occur from a bite, skin abrasion or when handling seals, or other seal products.
    
    • Day to 3-week incubation, finger becomes red, edematous, tender and painful. Can affect regional lymph nodes and joints. Untreated can lead to permanent stiffness of affected joints.
    • Drug of choice – tetracycline or doxycycline.
• Erysipelothrix rhusiopathiae – localized cutaneous form (fish poisoning) – red indurated pruritic/burning patches, diffuse cutaneous form, or rarely systemic bacteremia (endocarditis). Enters through skin abrasions.
• Salmonella – (S. enteritidis and S. thyphimurium) – contact with feces/fomites or consumption of meat and blubber. Can be found in healthy or clinically affected animals. In prevalence study S. bovismorbificans was most common, found in cattle. Can share serovars mon birds, marine mammals, cattle and humans.
• Mycobacterium (M. marinum) typically inoculated on elbow, knee, foot or fingers (rarely synovitis, osteomyelitis, ocular, laryngeal lesions. Can be infected and shed bacteria without clinical symptoms or have nonspecific clinical signs (lethargy). Cleaning of pools with high pressure contributes to aerosol formation (shed in respiratory secretions and also mucosal secretion, feces and urine). Seals found with M. tuberculosis complex, and trainer became sick with pulmonary tuberculosis (fatigue, weight loss, productive cough) two years after working with the animals. Patagonian sea lions are most often affected.
• Brucella – reproductive disease in dolphins but little pathology in true seals. Zoonotic potential of B ceti (cetaceans) and B pinnipedialis (seals). Study showed that bacteria was able to enter human macrophages but not multiply or survive. One case of laboratory worker developed chronic headache, fatigue and sinusitis (flu- like signs). Eating raw seafood can cause neurobrucellosis (intracerebral granuloma).
• Leptospira – mostly pinnipeds (leptospira interrogans pomona), involved in stranding and mortality events. Zoonotic potential unclear, but people have become sick from exposure to tissues and fluids during necropsies.
• Coxiella burnetii – gram negative intracellular bacteria, causative agent of Q fever. Enzootic in fur seals, pacific harbor seals and northern sea otters, and has been found in the placenta of harbor porpoises and stellar sea lions. Most affects placenta but recent reports of affecting brain tissues and a component of stranding in harbor seals. Causes flu like symptoms (sometimes GI) in humans.

Question 4

List a few marine mammal protozoal infections that can be potentially zoonotic.

Answer 4

Parasitic Zoonoses:

• Toxoplasma gondii – clinical cases and antibodies detected in whales, dolphins, seals, sea otters, manatee and polar bears. No risk for contracting through indirect contact, only through ingestion of meat. No documented cases, however, seroprevalence suggests likely transmission. Seroprevalence of native communities increased significantly with amount and frequency of marine mammal consumption.
• Trichinella spp – entire life cycle in one host, thus transmission is through consumption of infected meat (polar bear and walrus most likely to be infected). Most outbreaks associated with walrus meat (through predation on seals). Freezing may kill larvae of trichinella spiralis, however artic variant T. nativa is more freeze tolerant.
• Giardia spp – No reports of transmission from marine mammals to people, but giardia spp have been identified in multiple cetacean and pinniped species with high prevalence.
• Cryptosporidium spp - often associated severe diarrhea in mammalian species. Has been reported in multiple pinniped and cetacean species. No reports of transmission to humans but may be transmitted from infected people (food handlers) to meat. Can also occur via contaminated water.

Question 5

What cetacean fungal infection is potentially zoonotic?

Answer 5

Fungal Zoonoses:

• Infection with fungi requires spores from the environment, not the vegetative stages found in marine mammals.
• Lacazis (loboa) loboi – obligate pathogen causing chronic mycotic disease (lobomycosis) in dolphins that is transmitted to humans through skin abrasions. Central and South American tropics, Gulf of Mexico, Florida to S America.