title: Distribution and seasonal prevalence of bovine lungworms in selected areas in western Montana.
abstract: In a survey (Oct, 1967, through Aug, 1969) of the distribution and seasonal prevalence of bovine lungworms in beef herds in 3 western Montana counties (Park, Gallatin, and Ravalli), infected cattle were detected in 27 of 35 herds. Results of 2,125 fecal examinations indicated that 7.8% of all cattle were infected with Dictyocaulus viviparus. Lungworms were found in 6.6% of 1,038 calves (less than 12 months old), 11.5% of 755 yearlings (1 to 2 years old), and 3.3% of 332 cows (more than 2 years old). A distinct seasonal pattern existed in calf infections, with initial passage of larvae beginning in late July or August and persisting until November or December. Exposure of calves in 1 portion of the study area apparently was delayed until November, with patent infections continuing through March. Spontaneous loss of infections normally occurred after 3 to 4 months of patency. The mean rate of larval excretion in the feces of all infected cattle was 0.37 larvae per gram of feces (l/g). Larval output was relatively uniform within each geographic area regardless of host age, but varied considerably from one portion of the study area to another. The potential role of wild ruminants (deer, elk, and moose) in the epizootiology of D viviparus is discussed with respect to western range utilization practices.
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000469:parasitology; D004022:Dictyocaulus Infections / Q000453:epidemiology* / Q000469:parasitology; D005243:Feces / Q000469:parasitology; D005260:Female; D008168:Lung / Q000469:parasitology; D008297:Male; D009009:Montana; D012621:Seasons