Publication:

Usefulness of serology in diagnosis of different clinical presentations of ocular toxoplasmosis

Background Large proportions of acquired cases of ocular toxoplasmosis are reported with atypical presentations. The objectives of the study were to find out whether any correlation existed between serological findings of typical and atypical presentations of ocular toxoplasmosis as compared to cases presenting with non-toxoplasmic uveitis and to find out the proportion of various atypical presentations of ocular toxoplasmosis.

Methods It was a prospective observational study.The study subjects of ocular toxoplasmosis were tested for immunoglobulin M (IgM) and immunoglobulin G (IgG) toxoplasma antibody levels in serum by ELISA (enzyme-linked immunosorbent assay) technique. The proportion of atypical presentation among total toxoplasma cases and distribution of atypical cases were calculated.  Fisher’s exact test, one-way analysis of variance and Kruskal-wallis test were used as applicable.

Results Among the cases (n=35) thirteen patients had typical presentation of a retinochoroidal focus with an adjacent scar and 22 patients had atypical features. Control group consisted of 24 patients. Various types of presentations in atypical cases were retinitis patch without an adjacent scar (31.8%), intermediate uveitis (27.3%), papillitis (22.7%) retinal vasculitis and dense vitritis (9.09% each).  Mean IgG levels in typical cases (85.3±82.9 IU/ml) and atypical cases (47.5±66.2) were significantly higher than control group (6.6±3.4, p<0.001).

Conclusions Serology is a useful tool in the diagnosis of ocular toxoplasmosis with a compatible clinical picture as serum IgG levels are significantly elevated in both typical and atypical presentations of ocular toxoplasmosis as compared to cases presenting with non-toxoplasmic uveitis.