Background:

1. Cyathostomins: These are a type of worm (nematode) that commonly infect horses. Their presence is widespread.
2. Infection Consequences: When horses are infected, a condition called larval cyathostominosis can occur. This happens due to a sudden emergence of a large number of larvae from the worms.
3. Faecal Egg Count (FEC) Tests: This is a test that checks horse feces for the number of worm eggs. However, this test has limitations. Although it tells you how many eggs are being shed by the worms, it doesn’t give a clear picture of the total number of worms in the horse. It also doesn’t provide information about worms that are in the mucus lining or the lumen (interior) of the intestines.

Previous Research:

1. There’s been prior research on an ELISA (a type of laboratory test) called CT3, which detects antibodies (specifically IgG(T)) in horse serum. This test is useful for detecting worms that are present in the mucus lining or the lumen of the intestines.

Current Study:

1. Objective: The researchers are trying to refine and validate the CT3 ELISA for commercial use. They have samples from horses for which they already know the worm burden.
2. Optimisation: They improved the test by adding “calibrators” that help in quantifying the specific antibody (IgG(T)). With this quantification, they created a ‘serum score’ for each horse, indicating the level of infection.
3. Validation: They used another set of samples to check how well the optimized test worked. They aimed to determine the right serum score values that would indicate worm burdens of 1,000, 5,000, and 10,000 worms.
4. Performance: The test performed very well. Using statistical measures, they found that the test could accurately diagnose worm infections. Specifically, it had over 90% sensitivity (correctly identifying true infections) and more than 70% specificity (correctly identifying those without infections) at the chosen serum score thresholds.

Further Observations:

1. They studied the pattern of these antibodies in various situations:
   • They noticed that newborn horses (foals) initially get these antibodies from their mothers through colostrum (the first milk). This inherited protection drops over time, but then increases again as the foals start eating grass contaminated with the worms.
   • When they studied horse populations in different geographical areas, they found that the number of horses testing positive for the worms (using the CT3 test) was related to the risk of worm transmission in that area.

Commercial Use:

1. Based on their findings, they outlined criteria for using the test in a commercial setting.
2. They developed mathematical models (logistic regression) to predict the chances that a horse’s worm burden exceeds certain thresholds based on its serum score. These models performed similarly to the direct serum score threshold method.

Conclusion:

1. The CT3 test is valuable for veterinarians. It can help them identify horses with low worm burdens that may not need treatment. Moreover, it supports the diagnosis of worm infections in horses.