Evidence of Anaplasma phagocytophilum infection in an island population of Scandinavian moose (Alces alces) in the South-eastern Sweden

Abstract: In the second half of the 1990's the moose population on the island Öland declined drastically and the hunters decided to completely stop hunting for moose for a number of years. When the hunting commenced the hunters found the slaughter weights to be lower than expected and the number of calves were also low. The hunters then contacted the Swedish National Veterinary Institute who then initiated a project which this report is a part of. Samples from a total of 40 moose was collected, 32 out of 33 sampled moose were positive for antibodies against Anaplasma phagocytophilum and 4 out of 36 samples were positive by PCR for Ananplasma phagocytophilum. Out of these three were calves and one was a female yearling. Reported slaughter weights for calves were low and the number of observed calves per adult female were half compared to the mainland. This survey indicates that infection with Anaplasma phagocytophilum constitutes a contributing cause for the low number of observed calves in the moose population on the island of Öland.