FACTORS AFFECTING PARELAPHOSTRONGYLUS-TENUIS IN WHITE-TAILED DEER (ODOCOILEUS, VIRGINIANUS) FROM MAINE

White-tailed deer (Odocoileus virginianus) collected in Maine (USA) fr om November 1988 to December 1989 were examined for Parelaphostrongylu s tenuis. Relationships of deer age class, sex, collection year, and d eer density to prevalence and intensity of P. tenuis infections were a nalyzed. Prevalence increased with deer age (P < 0.001) and interactio n of deer age class and collection year (P < 0.001). Prevalence did no t vary by year in deer greater-than-or-equal-to 1 yr old (85%, n = 519 ), but was higher in fawns in 1988 (66%, n = 87) than 1989 (23%, n = 7 3, P < 0.001). Based on such yearly variations, prevalence in fawns du ring late autumn could provide an index of annual transmission of P. t enuis. Intensity of P. tenuis averaged 2.5 worms per infected fawn (SD = 2.8, n = 72) versus 3.9 (SD = 3.1, n = 375) in deer greater-than-or -equal-to 1 yr old (P = 0.032). Neither prevalence (P > 0.50) nor inte nsity (P > 0.50) of infection was associated with deer density over a range of 1.4 to 5.8 deer per km2. Heads and fecal samples from the sam e individuals (n = 42) provided prevalence estimates of 73% and 44%, r espectively. No differences in prevalence, intensity, or geographic di stribution of P. tenuis in adult deer collected in Maine during fall w ere evident between the late 1980's (this study) and the late 1960's ( Gilbert, 1973). Moose (Alces alces) populations increased from the 196 0's through 1980's in areas of Maine where >80% of adult deer carried P. tenuis, despite the risk of a lethal neurologic disease that occurs when moose become infected with the parasite.