Toxoplasmosis is a widespread, neglected disease with significant morbidity and mortality. The current
study aimed to investigate the potential effectiveness of azithromycin against the cystogenic Me
49 nonvirulent strain of Toxoplasma gondii after the 6th week post-infection (PI) in chronically infected
mice. Fifty laboratory-bred female Swiss albino mice were divided into five groups: G1: Non-
Infected, G2: Infected non-treated, G3: Infected and treated by azithromycin 200 mg/kg after the 6th
week PI for 3 days, G4: Infected and treated by azithromycin 200 mg/kg after the 6th week PI for 10
days and G5: Infected and treated by spiramycin 200 mg/kg after the 6th week PI for 2 weeks, brain
cysts number, size and histopathological changes were evaluated after 2 months.
The results showed that treating mice after the 6th week post-infection with azithromycin for 10 days
reduced number and size of brain cysts by 64% & 30%, respectively, but without significant difference
as compared with spiramycin-treated ones. Azithromycin treatment for 3 days achieved a greater reduction
(34%) in brain cyst size than the group treated with azithromycin for 10 days. But, it caused
the least reduction in brain cyst number (10%). Azithromycin treatment for 10 days improved the histopathological
changes in cerebral toxoplasmosis.