Birds of a Feather Spread Disease Together—Pacific Gulls as Potential Vectors of Coxiella burnetii From Australian Fur Seal Breeding Colonies
Abstract
Coxiella burnetii is a zoonotic pathogen known to cause abortion in wildlife.1 It has also been associated with decreasing populations of northern fur seals (Callorhinus ursinus) and Steller sea lions (Eumetopias jubatus).2 C. burnetii has been identified as a possible contributory cause to decreased pup production in Australian fur seals (Arctocephalus pusillus doriferus).3 Birds are known to act as vectors for many diseases4,5 and have been implicated as possible vectors for C. burnetii in northern hemisphere marine mammals6. Pacific gulls (Larus pacificus) are known to scavenge birthing remains from Australian fur seal breeding colonies3 and, in this current study, are hypothesized as possible vectors.
Pacific gulls were sampled at two locations during the Australian fur seal breeding season, one associated with an Australian fur seal breeding colony (Kanowna Island [KI]) and the other without Australian fur seals present (Seal Island [SI]). Oral swabs, cloacal swabs and blood were collected from 17 birds/location (n=34). Birds were additionally fitted with GPS telemetry. Swabs and serum were extracted for qPCR for three molecular markers specific to C. burnetii (com1, htpAB, and IS1111).
Detection rates were significantly different between the two colonies, with most oral and cloacal swabs positive on both com1 (94.1%; 88.2%) and htpAB (76.5%; 76.5%) on KI, whereas amplification was extremely poor for both at SI. Only KI serum samples showed amplification (17.7% for both com1 and htpAB). There was no IS1111 amplification in any sample from either location. GPS tracking of flight paths indicated that birds from both colonies made forays into the mainland, visiting freshwater bodies, dairy farms and refuse sites up to 25 km inland.
The combination of molecular and telemetry tools highlights the significant differences foraging ecology can have on the epidemiology of some pathogens. From this study, it is obvious that Pacific gulls can act as vectors for C. burnetii, but the implications thereof aren’t yet fully understood.
Acknowledgements
Our sincere thanks to Sean Best, a superb helicopter pilot. Also, a tremendous thank you to the institutional support we received from the Australian Rickettsial Reference Laboratories in conducting this research.
*Presenting author
+Student presenter
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