Research Summary - 3
Estimation of T. foetus organisms present in field samples using stochastic simulations
| Date/Time: |
9/13/2025
08:00
|
| Author: |
Tyler M Jumper |
| Clinic: |
Mississippi State University |
| City, State, ZIP: |
Starkville, MS 39759 |
T.M. Jumper, DVM
1
;
M. Thoresen, PhD
1
;
E.H King, DVM, MS, DACT
1
;
D. Loy, DVM, PhD, DACVM
2
;
D. Loy, DVM, PhD, DACVM
2
;
D.R. Smith, DVM, PhD, DACVPM (Epidemiology)
1
;
1Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, MS, USA
2Nebraska Veterinary Diagnostics Center, School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA
Introduction:
Tritrichomonas foetus, a protozoan parasite that is transmitted from the bull host to cows during coitus, can cause reproductive failure and is regulated at the state level. The newly developed direct RT-rtPCR provides potential advantages over previously used diagnostic modalities. The reported limit of detection of the RT-rtPCR is 1 T. foetus organism/100 μL, with a decrease in detectable RNA in samples that have <10 organisms/100 μL. It is generally believed that T. foetus infected bulls would have much higher levels of organisms in a preputial sample, however research is lacking. Therefore, the objective of this study was to estimate the number of T. foetus organisms in field samples submitted for direct RT-rtPCR testing.
Materials and methods:
Linear regression of samples with known concentrations of T. foetus and their concurrent cycle threshold (Ct) values were used to estimate the concentration of organisms from field samples submitted to a diagnostic laboratory for routine testing with the RT-rtPCR. A stochastic simulation of 5000 iterations was performed to represent the possible distribution of T. foetus organisms in samples.
Results:
The relationship between Ct values and T. foetus dilution in the reference data set was significant (R2=0.8715, p<0.0001). The simulated number of organisms/100 μL mean=10.41 (min=0.009, max=525.75) and median=2.76 (percentiles: 5th=0.17, 25th=0.88, 75th=8.71, 95th=42.90).
Significance:
These results show that 75% of simulated samples fall below the 10 organism/100 μL threshold, indicating that truly infected bulls might be misclassified as “not detected” which could have economic consequences for beef cattle producers.
