Hopping species and borders: detection of Bartonella spp. in avian nest fleas and arctic foxes from Nunavut, Canada

Abstract

Background: In a warmer and more globally connected Arctic, vector-borne pathogens of zoonotic importance may be increasing in prevalence in native wildlife. Recently, Bartonella henselae, the causative agent of cat scratch fever, was detected in blood collected from arctic foxes (Vulpes lagopus) that were captured and released in the large goose colony at Karrak Lake, Nunavut, Canada. This bacterium is generally associated with cats and cat fleas, which are absent from Arctic ecosystems. Arctic foxes in this region feed extensively on migratory geese, their eggs, and their goslings. Thus, we hypothesized that a nest flea, Ceratophyllus vagabundus vagabundus (Boheman, 1865), may serve as a vector for transmission of Bartonella spp.

Methods: We determined the prevalence of Bartonella spp. in (i) nest fleas collected from 5 arctic fox dens and (ii) 37 surrounding goose nests, (iii) fleas collected from 20 geese harvested during arrival at the nesting grounds and (iv) blood clots from 57 adult live-captured arctic foxes. A subsample of fleas were identified morphologically as C. v. vagabundus. Remaining fleas were pooled for each nest, den, or host. DNA was extracted from flea pools and blood clots and analyzed with conventional and real-time polymerase chain reactions targeting the 16S-23S rRNA intergenic transcribed spacer region.

Results: Bartonella henselae was identified in 43% of pooled flea samples from nests and 40% of pooled flea samples from fox dens. Bartonella vinsonii berkhoffii was identified in 30% of pooled flea samples collected from 20 geese. Both B. vinsonii berkhoffii (n = 2) and B. rochalimae (n = 1) were identified in the blood of foxes.

Conclusions: We confirm that B. henselae, B. vinsonii berkhoffii and B. rochalimae circulate in the Karrak Lake ecosystem and that nest fleas contain B. vinsonii and B. henselae DNA, suggesting that this flea may serve as a potential vector for transmission among Arctic wildlife.

Keywords: Arctic fox; Bartonella; Disease ecology; Flea; Geese; Nunavut; Vector-borne disease; Wildlife; Zoonotic.

Fig. 1

Photographs of eggs in an uninfested nest (a) and blood-covered eggs in a flea infested nest (b) in the Karrak Lake goose colony (Photos taken by Kayla Buhler in June 2019)

Fig. 2

Hypothesized mechanisms of Bartonella transmission in a terrestrial Arctic ecosystem. a Goose carcasses that are brought to dens may expose fox adults and kits to infected fleas. b Migrating geese may introduce Bartonella species from southern latitudes to fleas overwintering in nest material in the Arctic. Alternatively, nest fleas may expose geese to Bartonella if the bacteria can be maintained over the harsh arctic winter. c Collecting and caching eggs may result in transmission of Bartonella to foxes via nest flea bites or exposure to flea dirt on the surface of eggs. Alternatively, fleas may collect infected blood meals from foxes. d Predation of Arctic rodents may expose foxes to rodent fleas carrying Bartonella species. e Rodents may visit newly abandoned nests to consume egg remnants and may expose nest fleas to Bartonella species. Rodents may also be exposed to Bartonella species via flea feces or bites in nests