Summary
Schistosomiasis is a chronic and debilitating disease that threaten millions of people, particularly the rural poor areas in the developing world. In control of schistosomiasis, the use of drugs that are safe and effective will remain the main tool until a successful vaccine is produced. Referring to the possibility of appearance of drug resistant parasites, especially with retreatment regimens in endemic areas, search for new schistosomicidal is essential.
In the present study, mice were infected by subcutaneous injection of mice with 60 ± 10 S. mansoni cercariae.
Mice infected with S. mansoni cercariae are classified as following:
A) Immature stage:
• Group 1: Non-infected non-treated.
• Group 2: Infected non-treated.
• Group 3: Infected and treated with Nigella sativa oil daily for 2 weeks before infection (prophylactic group).
• Group 4: Infected and treated with praziquantel for 2 successive days 3 weeks post infection.
• Group 5: Infected and treated with Nigella sativa oil daily for 2 weeks starting from 2nd day post infection.
• Group 6: Infected and treated with Nigella sativa oil daily for 2 weeks starting from 2nd day post infection and praziquantel for 2 successive days 3 weeks post infection
All mice in this group sacrificed after 4 weeks post infection.
B) Mature stage:
Group 1: Non-infected non-treated.
Group 2: Infected non-treated.
Group 3: Infected and treated with Nigella sativa oil daily for 2 weeks before infection (Prophylactic group).
Group 4: Infected and treated with praziquantel for 2 successive days 6 weeks post infection.
Group 5: Infected and treated with Nigella sativa oil daily for 4 weeks starting from 2nd day post infection.
Group 6: Infected and treated with Nigella sativa oil daily for 4 weeks starting from 2nd day post infection and praziquantel for 2 successive days 6 weeks post infection.
All mice in this group sacrificed 8 weeks post infection.
- The therapeutic effect of each drug on S. mansoni infected mice was evaluated using the following:
I-Parasitological evaluation
1-Kato technique to detect S. mansoni eggs in mice feces.
2-Worm burden to detect number of worms after perfusion.
3-Oogram pattern to detect changes in the different developmental stages of ova in intestinal wall.
4-Tissue egg load (intestine and liver).
II-Histopathological examination of liver specimens.
III-Scanning electron microscopy examination of worms.
Results revealed that:
1-Worm burden:
Therapeutic treatment with Nigella sativa oil had a high significant decrease on mean number of immature worm burden either alone as (R% was 57%) or in combination with praziquantel as (R% was 55.67%), as regard prophylactic group, it showed moderate effect, as the (R% was 37%), however praziquantel had no effect on immature worm burden. Concerning mature worm burden, praziquantel and combination therapy had the highest significant decrease on mean number of total mature worm burden, (R% was 93.96 % &93.74%) respectively. Therapeutic treatment with Nigella sativa oil had a high significant effect as (R% was 57.51%). While, prophylactic group showed the least effect as (R% was 40.91%).
2- Oogram pattern:
The most evident effect observed in combined therapy and praziquantel groups, both groups had a high significant effect, as there was complete disappearance in the immature ova (0.0±0.0) & (0.10±0.32) respectively, both groups had the highest significant increase in the percentage of dead ova (98.2±4.02) & (98.1±2.13) respectively, both groups significantly decreased the percentage of mature ova (1.8±4.02) & (1.8±1.93) respectively. Therapeutic treatment with Nigella sativa oil had a high significant increase on percentage of dead ova (21.43±3.64) and a high significant decrease on percentage of immature ova (31.0±8.49), while it increased percentage of mature ova (47.57±10.7). Prophylactic treatment with Nigella sativa oil had only significantly increased the percentage of dead ova (14.75±6.5).
3-Tissue egg load (intestine and liver):
The most evident reduction in ova count in tissue was observed in combined group, with the highest detected percentage of reduction (R% was 75.76%) in hepatic tissue & (R% was 91.76%) in intestinal tissue. Praziquantel had a high significant reduction in ova count in hepatic tissue and intestinal tissues, (R% was 75.47%&91%). Nigella sativa oil had a moderate reduction in ova count in hepatic tissue (R% was 57.86%) & (R% was 81.45%) in ova count in intestinal tissue. The lowest percentage of reduction in ova count per gram of hepatic tissue was observed in prophylactic group, (R% was 51.46%) & (R% was 78.76%) in ova count in intestinal tissue.
II-Histopathological examination:
- Liver sections obtained from mice sacrificed 4 weeks post infection showed improvement of hepatic pathology in therapeutic of Nigella sativa oil, while prophylactic group, praziquantel and combined therapy showed no improvement of hepatic pathology.
-The most evident reduction in the mean number of hepatic granuloma /5 low power fields was observed in group treated with combined therapy as (R%) was (69.81%), praziquantel showed a high significant reduction on mean number of hepatic granuloma as (R%) was (60.67%), therapeutic treatment with Nigella sativa oil had a moderate reduction on mean number of hepatic granuloma, (R%) was (51.05%). The lowest percentage of reduction was observed in prophylactic group had the lowest percentage of reduction, (R%) was (37.81%).
-As regard the size of the granuloma, Nigella sativa oil treated group had a high significant reduction on the mean granuloma diameter, the (R% was 26.69%) with moderate improvement of hepatic pathology, praziquantel treated group showed moderate diminution in hepatic granuloma diameter, (R% was 19.9%) with slight improvement of hepatic pathology, the highest significant reduction in the mean granuloma diameter was observed in group treated by combined therapy as (R% was 27.06%) with moderate improvement of hepatic pathology and the least detected decrease in granuloma diameter was observed in prophylactic group as (R% was 14.85%) with slight improvement of hepatic pathology.
III-Scanning electron microscopy examination of worms
As regard the immature groups, the most evident effect on immature worms was achieved by Nigella sativa oil, it showed extensive tegumental destruction and edema of tegument, prophylactic group and combined group showed moderate effect. However, praziquantel only showed slight effect. As regard the mature groups, the most evident effect on mature worms was achieved by praziquantel and combined therapy in the form of severe reduction in the number and size of the tubercles with complete loss of spines. Therapeutic and prophylactic groups treated with Nigella sativa oil showed moderate effect on worm tegument.
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