In vivo assessment of the effects of methotrexate on latent toxoplasmosis

Abstract EN

Toxoplasma gondii (T.

gondii) has been shown to result in life-threatening encephalitis in immunocompromised patients after reactivation of dormant parasites.

The present work aimed to assess the effects of methotrexate on reactivation of latent toxoplasmosis alone and combined with a therapeutic combination of spiramycin, pyrimethamine and folinic acid on the progress of the disease.

Forty-four laboratory-bred Swiss albino male mice were infected with Me49 nonvirulent strain of T.

gondii and equally divided into four groups: infected untreated control (I); infected and treated with combination of spiramycin, pyrimethamine and folinic acid (II); Infected and received methotrexate (III); and infected and received both methotrexate, spiramycin, pyrimethamine and folinic acid (IV).

The mean number and size of tissue cysts in brain smears of mice of each group were determined, serum levels of anti-Toxoplasma IgM were assessed in different study groups by an enzyme linked immunosorbent assay and histopathological examination of brain and liver were done.

The results showed that the mean serum IgM level was significantly different in the treated groups compared to that in infected control group.

The highest level of serum IgM was found in the infected and received methotrexate group.

After treatment with spiramycin, pyrimethamine and folinic acid, it was significantly decreased.

In this study, reactivation of latent toxoplasmosis was observed by a significant increase in the mean number and sizes of Toxoplasma tissue cysts in brains of mice with established chronic toxoplasmosis after treatment with methotrexate alone or combined with spiramycin, pyrimethamine compared to both untreated chronically infected controls and infected mice treated with spiramycin, pyrimethamine and folinic acid.

Moreover, considerable pathological lesions in the brain and liver was observed in groups received methotrexate alone or combined with spiramycin, pyrimethamine compared to both untreated chronically infected controls and infected mice treated with spiramycin, pyrimethamine and folinic acid.