Ocular toxoplasmosis with positive polymerase chain reaction in peripheral blood – report of two cases, São Paulo State, Brazil

Abstract

Aims: To describe the use of polymerase chain reaction (PCR) in peripheral blood and demonstrate its importance in the clinical follow-up of patients with ocular toxoplasmosis.

Case description: Two immunocompetent patients were clinically diagnosed with acute ocular toxoplasmosis. The routine clinical evaluation consisted of fundus examination using binocular indirect ophthalmoscopy, color fundus photography, fluorescein angiography, and spectral domain optical coherence tomography. The serological diagnosis was made by ELISA (IgM, IgG) and confirmed by ELFA (IgG, IgM). The molecular diagnosis was made by PCR in peripheral blood using the B1 gene of Toxoplasma gondii as marker. The younger patient was male, had previous lesion in the right eye, complained of low visual acuity in the left eye and was under treatment. The older patient was male, had retinal detachment, and presented with sudden loss of acuity in the right eye. The fundus examination revealed chorioretinal scar in the left eye. IgG was reactive, IgM was non-reactive, and PCR was positive in the peripheral blood of both patients. New blood samples were collected for serological and molecular monitoring and PCR remained positive in both cases. Six weeks after treatment with oral sulfadiazine and pyrimethamine, the PCR yielded negative results.

Conclusions: The results show that T. gondii antigens may be found in peripheral blood during ocular reactivations and that PCR may be a good tool for the follow-up of patients with ocular toxoplasmosis.