To evaluate the hypothesis that the granuloma cell population in S. haematobium is different from that of S. mansoni infections, a hamaster animal model was established.
Infection of hamsters was induced by abdominal skin exposure of the male golden
hamsters with 300 cercariae. S. haematobium granuloma cell population in the small
intestine, urinary bladder, liver and spleen and those of S. mansoni granuloma in the
small instestine and liver of infected hamsters were histologically examined between 6 &
12 weeks post- exposure. In both species, the granuloma cell population was formed of
lymphocytes (47%), histiocytes (28%), eosinophils (16%) and polymorphs (8%). As
compared to granuloma cell population in S. haematobium ; S. mansoni granulomas
had: (a) higher population of eosinophils (28% vs. 11%), (b) lower population of
polymorphs (4% vs. 10% and histiocytes (22% vs. 31%) and (c) similar population of
lymphocytes (46% vs. 47%). The mean diameter of liver granuloma was higher in S.
mansoni (175.8 ± 12.34) than for S. haematobium (125.4 ± 16.12). As compared to S.
haematobium, the numbers of isolated (^+ and total worms were significantly higher in
S. mansoni (24.5± 2.7 vs. 7.3 ± 2.3; 2.3; 6.3 ± 0.8vs. 2.2 ± 0.5; 80±2.2 vs. 56.3 ±3.8,
p<.0.05). The heterogeneity of cell population granuloma suggests the involvement of
different immune mechanisms in their development. The cells achieving numerical
dominance in the granulomas were in the following order: lymplymphoyctes >
monocytes> eosinophils> Polymorhs. The difference in the granuloma cell population
between S.haematobium and S. mansoni may reflect different tissue reactions to the
deposited ova.