Immune Complexes Versus Larval Recovery In Evaluation Of The Chemotherapeutic Efficacy In Experimental Murine Toxocariasis

1Karam M. Maklad, 2Nagwa M. Kamal, 2Saedia A. Sayed El-Ahl and ³Amany M. Abd El-Wahab.

Departments of 1Parasitology, Faculty of Medicine, Ain Shams University, 2Parasitology and ³Microbiology, Faculty of Medicine For Girls, Al Azhar University, Cairo, Egypt.

The present study was designed to evaluate the efficacy of two broad-spectrum antiparasitic drugs; ivermectin and mebendazole (MBZ) in treatment of murine toxocariasis. Two parameters were assessed; larval recovery and determination of circulating immune complexes (CICs). Male Balb/c albino mice were infected with 750 larvated (L2) T.canis ova and designated according to treatment into untreated control, infected and treated with ivermectin (0.2 mg / kg), and infected and treated with MBZ (100 mg/kg) groups. Larval recovery from digested tissues was done after sacrification of 6 mice from each group at the end of 1st and 7th weeks post Infection (w.p.i). Blood samples were taken for assaying serum CICs from all mice groups by the end of every week through the entire experiment (1-7 w.p.i). Results revealed a reduction of the parasitism of all examined organs in the two treated groups. However, it was more pronounced in ivermectin treated (61.7%) than MBZ treated (51.2 %) groups. The larval distribution by organs showed a significant hepatic retention in the two treated mice groups compared to the control group by the end of 1st w.p.i. (40.83 ± 7.36, 19.67 ± 2.88, and 11.3 ± 2.16 respectively). While the posterior distribution of larvae to the carcass (10.5 ± 2.59, 30.5 ± 3.62, and 45 ± 7.52 respectively) was modified by the hepatic retention. By the end of 7th w.p.i. Larval recoveries showed a significant restriction of the access of the larvae to the cerebral components in the treated mice groups compared to controls (10.5 ± 1.87, 20.33 ± 2.75, and 43± 3.69 respectively). Investigation of the dynamics of CICs production revealed that sera of control animals showed CICs response by the end of 1st w.p.i. (Index 2.75) with persistent increase along the experiment till the end of the 7th w.p.i. (Index 3.1). In treated mice groups an observable reduction was recorded in CICs levels, and was more pronounced in the ivermectin treated (index 1.9 and 0.75) than MBZ treated (index 2.5 and 2) groups at the end of 1st and 7th w.p.i. respectively. This reduction could be attributed to larvistatic (hepatic retention) or larvicidal action of the drugs. It is concluded that ivermectin is more potent than MBZ in treatment of murine toxocariasis, and that evaluation of chemotherapeutic agents by larval recovery is essential and a valuable index.