Detection probability and Pasteurellaceae surveillance in bighorn sheep

Area of Science:

• Veterinary Microbiology
• Wildlife Disease Ecology
• Bacterial Pathogenesis

Background:

• Pasteurellaceae species are significant pathogens in bighorn sheep populations.
• Accurate detection of these bacteria is essential for effective herd management and conservation efforts.
• Variability in diagnostic test results can confound disease prevalence estimations.

Purpose of the Study:

• To investigate how detection probability influences the repeatability of bacterial culture results for Pasteurellaceae in bighorn sheep.
• To estimate occupancy probabilities of Pasteurellaceae biovariants within bighorn sheep herds.
• To determine the impact of detection probability on sample sizes required for accurate surveillance.

Main Methods:

• Collected oropharyngeal and lung swabs from free-ranging bighorn sheep in Colorado.
• Submitted samples immediately or after a 2-day delay for bacterial culture.
• Calculated detection and occupancy probabilities for cultured Pasteurellaceae biovariants.

Main Results:

• Detection probabilities for Pasteurellaceae biovariants were consistently ≤ 0.71.
• Delayed sample submission reduced microbial diversity and detection probability.
• Oropharyngeal swabs yielded higher detection probabilities than lung swabs.
• Estimated occupancy probabilities ranged from 0.37-0.89.
• Required sample sizes varied from 3 to >30 per sheep and 2 to 40 per herd for 95% detection confidence.

Conclusions:

• Detection probability is a critical factor affecting the reliability of bacterial culture results for Pasteurellaceae in bighorn sheep.
• Sample collection method (oropharyngeal vs. lung) and submission time influence detection rates.
• Confounding effects of the detection process must be addressed to enhance the rigor of wildlife disease surveillance.