Disease Surveillance in Main Hawaiian Island Hawaiian Monk Seals (Monachus schauinslandi)
IAAAM Archive
Robert C. Braun
Kaneohe, HI, USA


The Hawaiian monk seal (HMS; Monachus schauinslandi) population in the Northwestern Hawaiian Islands (NWHI) has declined approximately 60% since the late 1950s. Recently, the population in the main Hawaiian Islands (MHI) has increased, perhaps reestablishing itself since prerecorded history. Seals in the MHI may be exposed to a broader range of human, pet, livestock, and feral animal pathogens and their host species, compared to seals in the remote and relatively isolated NWHI. Concern for both the MHI and NWHI sub-populations is enhanced by the prospect of seals carrying disease from the MHI to the larger sub-populations in the NWHI. Studies on HMS movements and foraging habitats in the MHI and potential exposure to infectious diseases have recently begun. Between March 2003 and September 2004, twenty-one HMSs were captured and biomedically sampled, and the movements of ten seals were monitored using satellite-linked radio transmitters. All seals tested negative for canine adenovirus, calicivirus, morbillivirus, Phocine Herpes Virus, Leptospira sp,. and both feline and canine heartworm antigen/antibodies?. Six of 21 seals tested positive on complement fixation for Chlamydia. Five seals demonstrated positive titers to Sacrcocystus neurona, four to Neospora caninum, and four seals were positive to Toxoplasmoa gondii. Fecal cultures showed approximately half were positive for Escherichia coli 0157 and one was positive for Campylobacter sp. None were positive for Salmonella sp. Seals spent considerable time foraging, traveling, and resting in near-shore waters close to human population centers, agricultural activity, livestock ranges, and sources of land-based water runoff and sewage dispersal

In the last five years six HMSs were found dead in the MHI. Necropsies were performed on all six animals. Toxoplasmosis gondii was determined to be the cause of death for two of the animals. Leptospirosis was found in tissues in another two. This poster discusses the definitive diagnosis, pathology of those cases and relates the life history as well as use of coastal habitats, which may have provided exposure to these primarily terrestrial pathogens.


The author would like to acknowledge the support and assistance of : Charles Littnan, G. Antonelis, J. Baker, B. Stewart, P. Yochem, Shawn Farry, and L. Kashinsky.

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Robert C. Braun

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