Biochemical responses to Plasmodium spp. infection in geese: alterations in acute phase reactants, redox balance, and serum proteins

Abstract Goose farming is gaining importance due to the economic value of meat and by-products; however, despite frequent reports of Plasmodium spp. infections in waterfowls, data on systemic biochemical responses in domestic geese remain limited. This study investigated biochemical alterations associated with natural Plasmodium spp. infection in Anser anser domesticus , focusing on acute phase proteins (APPs), thiol–disulfide homeostasis (TDH), and serum protein profiles. Blood samples were collected from geese with Plasmodium infection defined by combined microscopic examination and PCR (n = 35) and from uninfected geese (n = 20) Serum levels of APPs [Serum amyloid A (SAA), haptoglobin (Hp), total sialic acid (TSA)], TDH parameters [Native thiol (NT), total thiol (TT), disulfide (DS)], and serum proteins (total protein, albumin, globulin) were analyzed. Plasmodium -infected geese showed significantly higher levels of APPs than uninfected geese, indicating a strong acute phase response. Meanwhile, thiol components (TT, NT, DS) were significantly lower in Plasmodium -infected geese, reflecting infection-associated oxidative stress. However, redox ratios remained stable, suggesting preserved redox balance through compensatory antioxidant mechanisms. No significant differences were observed in serum protein concentrations. Correlation analysis revealed that Hp positively correlated with DS and negatively with NT/TT%, highlighting an interaction between inflammation and oxidative imbalance. Principal component analysis (PCA) showed that multivariate differentiation between infected and uninfected geese was mainly associated with protein-related and thiol-based redox parameters. In conclusion, Plasmodium infection triggers a distinct inflammatory and oxidative response in domestic geese, without affecting total serum protein levels. The combined use of APPs and TDH markers provides a promising non-invasive approach for monitoring infection-related physiological responses in avian malaria, supporting their potential utility in veterinary practice.