An update on gastrointestinal nematodes in reindeer (Rangifer tarandus tarandus) in Iceland

Eurasian tundra reindeer (<i>Rangifer tarandus</i>) were introduced to Iceland from Norway in the late 18th century and have thrived in Eastern Iceland. In 2003-2005 the parasitic fauna was studied, and Icelandic reindeer were found to lack many parasites common to Norwegian reindeer. This study from 2018 provides an updated comparison. Abomasal content and faeces were collected from the 117 reindeer (63 adults, 22 yearlings, 17 calves, 15 age not recorded), from: 1 - West (N = 29), 2 - Central (N = 44), 3-9 - East (N = 40), not recorded (N = 4) management areas hunted in 2018. Not all animals were examined by all methods. Abomasal nematode counts (N = 81) were carried out in addition to faecal egg and larval counts, using modified McMaster (N = 111) and Baermann (N = 108). Abomasal nematodes were detected in 31 % of samples, with low mean abundance (48) and intensity (160). Males had higher prevalence (46 %) and mean abundance (89) than females (24 %; 29). The sheep gastrointestinal nematode (GIN) <i>Teladorsagia circumcincta</i> predominated, although, for the first time, single specimens of <i>Spiculopteragia boehmi (Gebauer,1932)</i> and a male nematode with morphology suggestive of <i>Ostertagia arctica</i>, a minor morph of <i>O. gruehneri</i>, were detected. <i>Trichostrongylus axei</i> was not detected. Trichostrongylidae and <i>Aonchotheca</i> egg prevalence was 35 % (mean abundance eggs per gram, EPG, 12, mean intensity 33 EPG) and 23 % (mean abundance 8 EPG; mean intensity 34 EPG) respectively. No faecal larvae were detected. There were geographic as well as sex related differences in abundance. Trichostrongylidae eggs prevalence, but not abundance, was higher in 2018 compared to 2005, and an opposite trend with abomasal nematode counts was seen. Reindeer in Iceland still have a low prevalence and abundance of GINs, dominated by <i>T. circumcincta</i>. The monitoring of GIN in this population provides a simple means of evaluating population health in a time with changing climate.