Evaluation of schistosomicidal activity of myrrh extract: parasitological and histological study.

Ninety mice were divided into three main groups: G. I (non-infected control), G. II (infected non treated control) and G. III (infected treated), which was further subdivided into 4 subgroups: IIIA, IIIB, IIIC & IIID, where the drug was administered in a dose of 500 mg/kg body weight for five days before infection for subgroup IIIA, on the 1st day post infection (PI) for subgroup IIIB, 21 days PI for subgroup IIIC and 45 days post infection for subgroup IIID. All animals were sacrificed 80 days after the start of the experiment. Anti-schistosomal activity was assessed parasitologically by estimating the percentage reducetion of worm burden, egg count/gm tissues (liver & intestine), and the oogram pattern; histologically & histopathologically by examination of jejunum using different stains. The percentage reduction of worm burden was 30.35%, 64.54%, 76.92% and 98.46% respectively when compared to the infected non-treated control G. The maximum effect of the drug was observed in subgroups IIIC & IIID. Also, there was marked reduction in the egg count in tissues (liver & intestine). In addition the oogram pattern showed that myrrh had high antischistosomal activity. The histologically and histopathologically infected untreated (GII), when compared to non-infected non-treated control G. showed apparent shortening and flattening of the jejunal villi with focal loss of the epithelial covering. Loss of PAS positive brush border of many enterocytes with goblet cells hyperplasia was seen. Bilharzial granulomas were frequently encountered in the submucosa and the musculosa with numerous eosinophils content. In subgroups IIIA & IIIB, there was mild amelioration of the mucosal structural abnormalities. The granulomas were less frequently seen with decrease of their eosinophils. In subgroups IIIC & IIID there was restoration of the jejunal mucosal continuity, marked decrease in the granulomas and paucity of eosinophils. The present data proved that myrrh has a valuable schistosomicidal effect against different maturation stages of S. mansoni. The chemotherapeutic effect was more evident when the drug was given to the infected mice on the 21st as well as on the 45th day PI. The drug proved a promising chemoprophylactic agent when used five days before exposure to infection.