Gastrointestinal nematodes in Icelandic reindeer (Rangifer tarandus tarandus)

Abstract

Reindeer (<i>Rangifer tarandus</i>) are host to gastrointestinal-tract nematodes (GINs) throughout the world. Some populations of reindeer exist in almost complete isolation from others, and this can have a key influence on the species and infection rates of GINs. An example of an isolated reindeer population occurs in Iceland. In this study, I have investigated the prevalence of GINs in Icelandic reindeer in a range of age gender and area classes. In total, I checked for the presence of GINs in fecal and abomasum samples of 115 reindeer, including adult females (n= 72) and males (n= 29), as well as 14 calves. The fecal samples were analyzed based on the McMaster and Baermann method. The reindeer samples analyzed in this study were from individuals shot during August–September 2018 in eight hunting management areas of eastern Iceland. Analysis of fecal samples for parasite eggs revealed an overall mean prevalence for Trichostrongylidae and <i>Capillaria</i> sp. of 35.1% and 22.5%, respectively. A total of four species of nematode parasites were found in the abomasum: <i>Telodorsagia circumcincta</i> and its minor morphotype <i>T. trifurcata, Spiculopteragia spiculoptera, Ostertagia gruehneri</i> and <i>Ostertagia</i> sp. Interestingly, overall male individuals showed higher prevalence and probability of nematode infection than females, based on egg counts. My study also revealed <i>Ostertagia gruehneri</i> in one adult male which was not reported in previous studies conducted in Iceland. Probability of <i>Capillaria</i> sp. infections was significantly different in the GLM model with animals from the west-central areas having significantly lower infection prevalence than the other areas. I conclude that my study suggests the Icelandic reindeer shows the healthy status in the country with an overall lower parasite prevalence than detailed in earlier studies. However, the low prevalence of GINs in this study might be associated with the lack of ‘freshness’ of the samples. However, no study has evaluated parasite detection with samples that have been frozen for some time, nevertheless laboratory tests at the site right after collection could improve future studies.