DAO 122:185-193 (2017)  -  DOI: https://doi.org/10.3354/dao03073

Colony-level assessment of Brucella and Leptospira in the Guadalupe fur seal, Isla Guadalupe, Mexico

E. Carolina Ziehl-Quirós1,3, María C. García-Aguilar2,*, Eric Mellink

1Departamento de Biología de la Conservación and 2 Departamento de Oceanología Biológica, Centro de Investigación Científica y de Educación Superior de Ensenada, Carretera Ensenada-Tijuana No. 3918, Zona Playitas, 22860 Ensenada, Baja California, Mexico
3Present address: Londres 1948 # 36, Col. Olímpica, Delegación Coyoacán, 04710 CDMX, Mexico
*Corresponding author:

ABSTRACT: The relatively small population size and restricted distribution of the Guadalupe fur seal Arctocephalus townsendi could make it highly vulnerable to infectious diseases. We performed a colony-level assessment in this species of the prevalence and presence of Brucella spp. and Leptospira spp., pathogenic bacteria that have been reported in several pinniped species worldwide. Forty-six serum samples were collected in 2014 from pups at Isla Guadalupe, the only place where the species effectively reproduces. Samples were tested for Brucella using 3 consecutive serological tests, and for Leptospira using the microscopic agglutination test. For each bacterium, a Bayesian approach was used to estimate prevalence to exposure, and an epidemiological model was used to test the null hypothesis that the bacterium was present in the colony. No serum sample tested positive for Brucella, and the statistical analyses concluded that the colony was bacterium-free with a 96.3% confidence level. However, a Brucella surveillance program would be highly recommendable. Twelve samples were positive (titers 1:50) to 1 or more serovars of Leptospira. The prevalence was calculated at 27.1% (95% credible interval: 15.6–40.3%), and the posterior analyses indicated that the colony was not Leptospira-free with a 100% confidence level. Serovars Icterohaemorrhagiae, Canicola, and Bratislava were detected, but only further research can unveil whether they affect the fur seal population.


KEY WORDS: Arctocephalus townsendi · Infectious diseases · Epidemiology · Introduced species · Isla Guadalupe · Serology · Bayesian approach


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Cite this article as: Ziehl-Quirós EC, García-Aguilar MC, Mellink E (2017) Colony-level assessment of Brucella and Leptospira in the Guadalupe fur seal, Isla Guadalupe, Mexico. Dis Aquat Org 122:185-193. https://doi.org/10.3354/dao03073

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