Age-related comparative study of C-reactive protein, lipid profile biomarkers, and strongyle nematode...

Gastrointestinal (GI) parasitic infection remains one of the most prevalent and economically significant health challenges in equine populations. The infective stages of GI parasites can activate systemic inflammatory responses and disrupt lipid metabolism leading to exacerbation of parasitic infection. Moreover, age-related low-grade chronic inflammation may further contribute to the persistent infection which impacts the health status of individual horses.

This study examined serum levels of the inflammatory marker C-reactive protein (CRP) and lipid profile parameters to identify age-related patterns in horses in the high prevalence area of GI parasitic infection in Southern Thailand.

Seventy-seven horses were categorized into four age groups: foal (<1 year); young (1-3.99 years); early adult (4-10 years); and late adult (>10 years) and were examined for fecal helminth eggs and fecal egg count (EPG) using a modified McMaster technique. The serum CRP, and lipid profile parameters including total cholesterol (TC), total triglyceride (TG), high-density lipoprotein (HDL-C), and low-density lipoprotein (LDL-C), LDL: HDL, and TC:HDL ratios were determined.

Strongyle nematodes, including cyathostomins and Strongylus vulgaris were detected with the prevalence >60% of horses across all age groups. CRP, TC, and LDL-C levels increased significantly with age (p < 0.01), while HDL-C levels significantly declined in the late adult group when compared with other age groups (p = 0.0037). Among all age groups of horses, Spearman correlation (ρ) and binary logistic regression (odd ratio: OR [95%CI]) revealed that serum CRP, and LDL-C levels were positively associated with the EPG of strongyle nematode helminths. While HDL-C levels showed negative correlation.

HDL, and TC:HDL ratios were identified as the risk factors for strongyle nematode GI infection. Using the ROC analysis, the cut-off values of CRP (>0.49 mg/L; %sensitivity [SS] = 72.97, %specificity [SP] =75.00), LDL: HDL (>2.476; %SS=64.29, %SP=71.43), and TC: HDL (>5.198; %SS=51.22, %SP=83.33%) could help predict the strongyle nematode GI parasitic infection in horses.

These findings highlight the diagnostic potential of CRP and cholesterol index as the prognostic biomarkers and disease monitoring in equine strongyle nematode infection to provide the proper management and intervention to current parasite management strategies.