A Nearctic parasite in a Palearctic host: Parelaphostrongylus andersoni (Nematoda; Protostrongylidae) infecting semi-domesticated reindeer in Alaska

• Parelaphostrongylus andersoni causes muscular and lung pathology in Nearctic cervids.
• We found P. andersoni in an introduced, semi-domesticated reindeer herd in Alaska.
• Infection of these reindeer may have occurred through indirect contact with native caribou.
• This nematode may cause subtle deleterious impacts on commercial herding activities.

Parelaphostrongylus andersoni is a muscle-dwelling protostrongylid nematode that infects caribou and white-tailed deer across North America, and can cause significant muscular and pulmonary pathology in these species. We collected 44 fecal samples from semi-domesticated reindeer (Rangifer tarandus tarandus) from the Kakarak herd of western Seward Peninsula, Alaska, USA. This herd has no record of historical contact and extremely limited possibility of contemporary contact with native Grant’s caribou (Rangifer tarandus granti) of the Western Arctic herd. Fecal samples were processed using the Baermann technique, and 22.7% (n = 10) were positive for protostrongylid dorsal-spined larvae (DSL). Genomic DNA extracted from individual DSL from each of the ten positive reindeer (total of 48 DSL) was amplified by PCR targeting the ITS-2 region of ribosomal RNA. Forty of 48 DSL were successfully sequenced and confirmed as P. andersoni and one representative sequence for each of the ten positive samples was deposited in GenBank. No other protostrongylids, including Varestrongylus sp., presumed to be widespread across caribou range, and Elaphostrongylus rangiferi, which could have been introduced with reindeer from Eurasia, were detected in these samples. P. andersoni is likely widespread among introduced reindeer in Alaska, potentially causing subtle but deleterious effects with negative economic impacts on commercial herding activities.

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