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False-positive Ascaris suum egg counts in pigs
J Boes1, P Nansen, L S Stephenson
1Danish Centre for Experimental Parasitology, Department of Veterinary Microbiology, Royal Veterinary and Agricultural University, Frederiksberg C, Denmark. jbo@kvl.dk
International Journal for Parasitology
|July 1, 1997
Summary
False-positive Ascaris suum egg counts in pigs are common. This study suggests coprophagia and geophagia, influenced by housing, cause these inaccurate results in pig fecal samples.
Area of Science:
- Veterinary Parasitology
- Animal Science
- Farm Management
Background:
- False-positive Ascaris suum egg counts in pig feces are frequently observed.
- These inaccuracies impact diagnostic reliability in both experimental and natural settings.
Purpose of the Study:
- To investigate the prevalence and contributing factors of false-positive Ascaris suum egg counts in pigs.
- To compare diagnostic accuracy between indoor and pasture housing systems.
Main Methods:
- Analysis of data from 12 Ascaris suum infection experiments in pigs.
- Comparison of false-positive rates and positive predictive values between indoor and pasture housing.
- Correlation analysis between egg counts of true-positive and false-positive pigs housed together.
Main Results:
- False-positive fecal samples ranged from 4% to 36%, with higher prevalence and egg counts in indoor experiments.
- The positive predictive value was significantly lower in indoor (45%) compared to pasture (89%) experiments.
- A positive correlation existed between egg counts of true-positive and false-positive pigs penned together.
Conclusions:
- False-positive Ascaris suum egg counts in pigs are likely due to coprophagia (indoor) and coprophagia/geophagia (pasture).
- Housing and management factors significantly influence the prevalence and magnitude of these false-positive results.