Authors

Discussion

In our previous study, administration of 5mg prednisolone for five days pre-Schistosoma haematobium infection in guinea-pigs elicited establishment of the parasite evidenced by inflammatory reactions and vacuolations in the liver and bladder cells. This study further investigates the ability of low doses of prednisolone given for short duration to induce more S. haematobium provoked histologic changes in infected guinea-pigs.  Guinea-pigs were shared into six groups and the infected groups were subcutaneously injected with 250-300 S. haematobium cercariae. Twenty infected guinea-pigs each in group I and II were given 0.5mg (I0.5) and 1.5mg (I1.5) prednisolone respectively a day before infection and on day 5 post infection.  Group III comprised 20 unimmunossuppressed infected (UI) guinea-pigs while groups IV and V comprised groups of animals given 0.5mg (D0.5) and 1.5mg(D1.5) prednisolone a day before infection and on day 5 post infection. Group VI is the normal group of 10 guinea-pigs. Guinea-pigs were killed, perfused, worms recovered and the liver, lungs, spleen, intestine, and bladder removed for histopathological examination at 6, 8, 11, 14 and 16 weeks pi. Six to sixteen weeks pi, worm recovery was higher in I1.5 group than in I0.5 group but the number of worms recovered from the immunosuppressed groups was higher than the UI group. The tissue sections of the normal, D0.5, and D1.5 guinea-pigs were normal from 6-16 weeks pi. No histologic change was seen in liver sections of UI while changes were only observed in the lungs at 16th week pi. Liver sections of the I0.5 at the 6th week pi showed mild-moderate hepatocyte degeneration, which progressed to only necrosis by 16th week pi. Liver sections of I1.5 guinea-pigs at the 6th week pi showed mildly haemorrhagic hepatic lobules with severe vacuolar degeneration of hepatocytes, which became severe hepatocyte necrosis at week 8. By 11th week pi, hepatocyte degeneration was observed again and at 16th week, became widespread. Sections from the lungs were devoid of visible lesions until week 11 pi. Although the characteristic S. haematobium granulomas were not recorded, administration of low doses of prednisolone (especially 1.5mg/kg) for short duration could enhance the establishment of S. haematobium in guinea-pigs.