September 2, 2011

Recent Disease Investigation from Wildlife Disease Association Newsletter

In the Spotlight: Recent Disease Investigation from Wildlife Disease Association Newsletter

Nordic Section Quarterly Report of Wildlife Disease Incidents for April, May and June 2011

Severe nose bot fly infestation in a wild reindeer flock in Southern Norway

In the July 2011 Wildlife Disease Association newsletter, Bjørnar Ytrehus and Kjell Handeland from the Norwegian Veterinary Institute submitted the following disease report summary.

In the middle of May 2011 a hunter observed a flock of 30-40 wild tundra reindeer on the southern part of Hardangervidda ( 8° E, 60°N) showing signs of lethargy, respiratory distress and complete lack of fear. On close view he observed “worms creeping out of the nose of them”.

A young animal was culled and the head submitted for laboratory examination. At reception, the tongue, pharynx and larynx had been removed and could therefore not be inspected. In the nostrils, on the muzzle and cheeks and within the nasal conchae about 30 third-stage larvae of the reindeer nose bot fly (Cephenemyia trompe) were found. The larvae were also found in the tissues around the retropharyngeal lymph nodes and lateral to the pharynx (figure 1). The adjacent lymph nodes showed follicular hyperplasia with a greenish discoloration and moist cut surfaces. The tissues surrounding the larvae show a greenish discoloration and edema.

The local wildlife manager was urged to follow the affected reindeer flock, but it could not be reloacted. A few other small flocks that were observed did not show any obvious signs of disease.

The nose bot fly is a common problem in domesticated reindeer herds in northern Norway, and there are large variations in infection levels between years, districts and individuals (Nilsen, 1995). Little is known about the impact of this infestation in the wild reindeer populations in southern Norway. However, the clinical signs observed in the reported flock may indicate severe health distress by heavy infestation, possibly most pronounced when the third-stage larvae are in the migratory process of leaving the host.