Evaluation of anthelmintic resistance in livestock parasites using observational data and hierarchical models
Research output: Contribution to conference › Poster › Research
Documents
- Abstracts 2010
Final published version, 118 KB, PDF document
Anthelmintic resistance is an increasing challenge in the control of parasites in livestock.
The fecal egg count reduction test (FECRT) is the practical gold standard method for
evaluating resistance, but the interpretation is complicated due to high levels of
variability. Several factors contribute to cause this high variability and these must be
taken into account to accurately identify a reduction in anthelmintic efficacy. To address
this problem, we developed a hierarchical statistical model for analysis of FECRT data
from multiple farms. The model includes animal effect and farm clusters as random
effects. Resistance classifications are based on model adjusted lower confidence limit
(LCL) values of predicted mean efficacies on each farm. The model was used to evaluate
the efficacy of pyrantel embonate paste from 64 Danish horse farms. On these farms 614
out of 1644 horses had egg counts = 200 eggs per gram (EPG) and were treated. Post
treatment samples and information on age, gender and farm zip code were collected for
each horse. In addition, individual coprocultureswere performed on all pretreatment fecal
samples to determine the presence of Strongylus vulgaris, with 31farms (48.4 %) testing
positive. The efficacy of pyrantel was unaffected by the presence of S. vulgaris on the
farm. The cutoff LCL values used for classifying farms as pyrantel resistant were: >92%:
no resistance, 88-92%: suspect resistance, and <88%: resistance. Using model-adjusted
LCLs, we classified 7 (10.93 %) farms as pyrantel resistant, 5 (7.81 %) as suspect
resistant and the remainder of farms (81.25%) as not resistant. In comparison with
unadjusted LCLs, the model provided a more stable classification of farms with a 1.1 %
12
false discovery rate. The statistical model presented here can be adapted to handle
FECRT data obtained from other livestock species, drug types, and parasite species.
Original language | English |
---|---|
Publication date | 2010 |
Publication status | Published - 2010 |
Event | Joint Spring Symposium. Danish Society for Parasitology and Danish Society for Tropical Medicine & International Health - Copenhagen, Denmark Duration: 29 Nov 2010 → … |
Conference
Conference | Joint Spring Symposium. Danish Society for Parasitology and Danish Society for Tropical Medicine & International Health |
---|---|
Country | Denmark |
City | Copenhagen |
Period | 29/11/2010 → … |
Number of downloads are based on statistics from Google Scholar and www.ku.dk
ID: 18879217