Hanni Krista D, Mazet Jonna A K, Gulland Frances M D, Estes James, Staedler Michelle, Murray Michael J, Miller Melissa, Jessup David A
Wildlife Health Center, School of Veterinary Medicine, University of California, Davis, California 95616, USA.
J Wildl Dis. 2003 Oct;39(4):837-50. doi: 10.7589/0090-3558-39.4.837.
The southern sea otter (Enhydra lutris nereis) population in California (USA) and the Alaskan sea otter (E. lutris kenyoni) population in the Aleutian Islands (USA) chain have recently declined. In order to evaluate disease as a contributing factor to the declines, health assessments of these two sea otter populations were conducted by evaluating hematologic and/or serum biochemical values and exposure to six marine and terrestrial pathogens using blood collected during ongoing studies from 1995 through 2000. Samples from 72 free-ranging Alaskan, 78 free-ranging southern, and (for pathogen exposure only) 41 debilitated southern sea otters in rehabilitation facilities were evaluated and compared to investigate regional differences. Serum chemistry and hematology values did not indicate a specific disease process as a cause for the declines. Statistically significant differences were found between free-ranging adult southern and Alaskan population mean serum levels of creatinine kinase, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, calcium, cholesterol, creatinine, glucose, phosphorous, total bilirubin, blood urea nitrogen, and sodium. These were likely due to varying parasite loads, contaminant exposures, and physiologic or nutrition statuses. No free-ranging sea otters had signs of disease at capture, and prevalences of exposure to calicivirus, Brucella spp., and Leptospira spp. were low. The high prevalence (35%) of antibodies to Toxoplasma gondii in free-ranging southern sea otters, lack of antibodies to this parasite in Alaskan sea otters, and the pathogen's propensity to cause mortality in southern sea otters suggests that this parasite may be important to sea otter population dynamics in California but not in Alaska. The evidence for exposure to pathogens of public health importance (e.g., Leptospira spp., T. gondii) in the southern sea otter population, and the naïveté of both populations to other pathogens (e.g., morbillivirus and Coccidiodes immitis) may have important implications for their management and recovery.
美国加利福尼亚州的南部海獭（Enhydra lutris nereis）种群以及美国阿留申群岛链的阿拉斯加海獭（E. lutris kenyoni）种群近期数量有所下降。为评估疾病是否是导致数量下降的一个因素，通过评估血液学和/或血清生化值以及利用1995年至2000年正在进行的研究中采集的血液检测六种海洋和陆地病原体的暴露情况，对这两个海獭种群进行了健康评估。对72只自由放养的阿拉斯加海獭、78只自由放养的南部海獭以及（仅针对病原体暴露情况）康复设施中的41只虚弱的南部海獭的样本进行了评估和比较，以调查区域差异。血清化学和血液学值并未表明存在特定疾病过程是导致数量下降的原因。在自由放养的成年南部海獭和阿拉斯加海獭种群的平均血清肌酐激酶、碱性磷酸酶、丙氨酸氨基转移酶、天冬氨酸氨基转移酶、钙、胆固醇、肌酐、葡萄糖、磷、总胆红素、血尿素氮和钠水平之间发现了具有统计学意义的差异。这些差异可能是由于寄生虫负荷、污染物暴露以及生理或营养状况的不同所致。没有自由放养的海獭在捕获时有疾病迹象，杯状病毒、布鲁氏菌属和钩端螺旋体属的暴露率较低。自由放养的南部海獭中抗刚地弓形虫抗体的高流行率（35%）、阿拉斯加海獭中缺乏针对该寄生虫的抗体以及该病原体在南部海獭中导致死亡的倾向表明，这种寄生虫可能对加利福尼亚州海獭种群动态很重要，但对阿拉斯加则不然。南部海獭种群中暴露于具有公共卫生重要性的病原体（如钩端螺旋体属、刚地弓形虫）的证据，以及两个种群对其他病原体（如麻疹病毒和粗球孢子菌）的易感性，可能对它们的管理和恢复具有重要意义。
