A lymphatic dwelling filarioid nematode, Rumenfilaria andersoni (Filarioidea; Splendidofilariinae), is an emerging parasite in Finnish cervids

• Published in: Parasites & Vectors
• Main Authors: Sauli Laaksonen, Antti Oksanen, Eric Hoberg
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2015
• Subjects: Lymphatic filariosis; Rumenfilaria andersoni; Cervids; Emerging parasites; Climate change; Infectious and parasitic diseases; RC109-216; Arctic; Fennoscandia; Moose; Northern Finland; Tundra
• Online Access: https://doi.org/10.1186/s13071-015-0835-0; https://doaj.org/article/2a2b44ba07974539820ce61bf6700304

Abstract Background Recent studies revealed expansion of filarioid nematodes into northern Finland. In addition to Setaria tundra, an abundant filarioid, Rumenfilaria andersoni, was found inhabiting the lymphatic vessels of reindeer. Our study explores the dynamics of the rapid geographic expansion of R. andersoni, defining prevalence and density of microfilariae among 4 new cervid host species in Finland while developing a context for host-parasite ecology in Fennoscandia and more broadly in the Arctic and boreal regions. Methods Blood samples were evaluated for presence of microfilariae from 1576 semi-domesticated reindeer, 8 captive reindeer, and free-ranging cervids including 105 wild forest reindeer, 862 moose, 114 white tailed deer and 73 roe deer in 2003–2006 (−2010). Additionally, the prepatent period and the efficacy of ivermectin treatment were investigated. Results Rumenfilaria andersoni was found to be a common and abundant parasite in reindeer (0-90%) and wild forest reindeer (41-100%). Also moose (0-12%), white-tailed deer (15-22%) and roe deer (3%) were revealed as definitive hosts. Ivermectin was not effective against adult parasites. The prepatent period was estimated to be about five months. Conclusions Rumenfilaria andersoni was identified in 3 endemic cervid species and the introduced white-tailed deer, all constituting previously unrecognized host species in the Palearctic. Among moose, the prevalence and intensity were substantially lower than levels observed among subspecies of reindeer. White-tailed deer had a relatively high prevalence and density of R. andersoni microfilariae (rmf), whereas our limited data for roe deer indicated that the nematode may not have been abundant. Density and prevalence of rmf in moose and white tailed deer suggests the nematode may be adapted to these species, and that these cervids may be among the primary hosts of R. andersoni and reservoirs for transmission in Finland. Our current data suggest that R. andersoni became established in Finland recently, ...