Active and passive disease surveillance in wild turkeys (Meleagris gallopavo) from 2008 to 2018 in Pennsylvania, USA

There are increasing concerns about the effects of disease on wild turkeys (Meleagris gallopavo). Yet, many management agencies lack adequate data on wild turkey diseases and pathogens to address this concern. Toward that end, the Pennsylvania Game Commission increased surveillance efforts on wild turkeys beginning in 2013 (referred to hereafter as the enhanced surveillance period). From 2008-2018, 121 wild turkeys from Pennsylvania were submitted for necropsy, with 102/121 (84.3%) submitted during the enhanced surveillance period (2013-2018). We examined cases to determine causes of morbidity/mortality through gross and microscopic examinations and ancillary tests. The most common causes of morbidity/mortality in the examined wild turkeys were avian pox (66/121; 54.5%), chronic dermatitis (15/121; 12.4%), and trauma (10/121; 8.3%). We diagnosed additional diseases for the first time or more frequently during the enhanced surveillance period, including histomoniasis (7/121; 5.7%) and infectious sinusitis (1/121; 0.8%). Skin lesions were the most common cause of submission (94/121; 77.7%) and were most often attributed to avian pox (66/94, 70.2%), chronic dermatitis (15/94; 16.0%), or lymphoproliferative disease (3/94; 3.2%). During 2013-2018, tissues and sera were collected from any diagnostic cases and hunter-harvested turkeys to create a tissue repository. We used these samples to test for infection or exposure to specific pathogens. We found that 75.3% (61/81) of wild turkeys were positive for lymphoproliferative disease virus, 61.9% (52/84) for Heterakis gallinarum, 28.6% (10/35) for Toxoplasma gondii, and 15.6% (15/32) for Borrelia burgdorferi. We detected antibodies (indicating exposure) to avian paramyxovirus-1 in 34.9% (22/63) of the wild turkeys and West Nile virus in 21% (13/62), but none were seropositive to influenza A viruses (0/62; 0%). The presence of diseases and pathogens in wild turkeys in Pennsylvania are being defined through active and passive surveillance approaches. Such data can begin to address the broader questions of disease impacts on wild turkey populations.