Toxoplasma IgM (IgM) is a sensitive indicator of primary toxoplasmosis; but with limited specificity,
and it may occasionally be sustained in blood serum for extended periods, ranging from several
months to years, following the first infection. The Toxo IgG avidity assay is a currently employed diagnostic
method for accurately assessing the time it takes to acquire an infection and determining the
initial T. gondii infection. This study evaluated Toxoplasma IgG avidity testing in new-borns diagnosed
with cholestasis on 92 neonates presented with cholestasis, whose blood samples were assessed
for the presence of toxoplasmosis using IgG and Toxo IgG Avidity ELISA tests. Biochemical changes
including the lipid profile, liver and renal functions were also evaluated. ELISA test revealed Toxo
IgG seropositivity at 52.2% (29.43±17.86IU/ml). Toxo IgG avidity tested low at 56.5%, high at
34.8%, and borderline at 8.7% (0.38 ±0.31) with a significant association (P<0.001) at a cut-off value
of 0.315. IgG titre was significantly correlated with direct bilirubin (P=0.029), AST (P<0.001), ALT
(P<0.001), ALP (P=0.041), PC (P=0.003), INR (P=0.041), urea (P=0.021), and triglyceride (P=0.022).
Toxo IgG avidity showed a significant (P<0.001) negative association with total bilirubin, direct bilirubin,
AST, ALT, PT, INR, and a significant positive association with PC (P<0.001), GGT (P=0.01).