DAO 106:187-196 (2013)  -  DOI: https://doi.org/10.3354/dao02659

Age-dependent prevalence of anti-Brucella antibodies in hooded seals Cystophora cristata

Ingebjørg H. Nymo1,*,**, Morten Tryland1,**, Anne Kirstine Frie2,**, Tore Haug2,**, Geoffrey Foster3, Rolf Rødven4,**, Jacques Godfroid1,**

1Section of Arctic Veterinary Medicine, Norwegian School of Veterinary Science, Stakkevollveien 23, 9010 Tromsø, Norway
2Institute of Marine Research, PO Box 6404, 9294 Tromsø, Norway
3SAC Consulting Veterinary Services, Drummondhill, Stratherrick Road, Inverness IV2 4JZ, UK
4Bioforsk—Norwegian Institute of Agricultural and Environmental Research, PO Box 2284, 9269 Tromsø, Norway
*Email:
**Member of the Fram centre–High North Research Centre for Climate and the Environment, 9296 Tromsø, Norway

ABSTRACT: Investigations of hooded seals Cystophora cristata have revealed high prevalences of Brucella- positive seals in the reduced Northeast Atlantic stock, compared to the increasing Northwest Atlantic stock. This study evaluated the relation between Brucella-serostatus in seals in the Northeast Atlantic stock and age, sex, body condition and reproduction. Bacteriology documented which animals and organs were B. pinnipedialis positive. No relationship was observed between Brucella-serostatus and body condition or reproductive traits. Pups (<1 mo old) had a substantially lower probability of being seropositive (4/159, 2.5%) than yearlings (6/17, 35.3%), suggesting that exposure may occur post-weaning, during the first year of life. For seals >1 yr old, the mean probability of being seropositive decreased with age, with no seropositives older than 5 yr, indicating loss of antibody titre with either chronicity or clearance of infection. The latter explanation seems to be most likely as B. pinnipedialis has never been isolated from a hooded seal >18 mo old, which is consistent with findings in this study; B. pinnipedialis was isolated from the retropharyngeal lymph node in 1 seropositive yearling (1/21, 5%). We hypothesize that this serological and bacteriological pattern is due to environmental exposure to B. pinnipedialis early in life, with a subsequent clearance of infection. This raises the question of a reservoir of B. pinnipedialis in the hooded seal food web.


KEY WORDS: Pinniped · Pups · Brucellosis · Serostatus · Bacteriology · Infection clearance · Atlantic hooded seal stock · Food web


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Cite this article as: Nymo IH, Tryland M, Frie AK, Haug T, Foster G, Rødven R, Godfroid J (2013) Age-dependent prevalence of anti-Brucella antibodies in hooded seals Cystophora cristata. Dis Aquat Org 106:187-196. https://doi.org/10.3354/dao02659

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