Schistosoma haematobium (Egyptian Strain): Rate of Development and Effect of Praziquantel Treatment

Abstract

This study investigates the development of the Egyptian strain of Schistosoma haematobium and the resultant immunohistopathology and biochemical changes in organs affected. In addition, the response of different developmental stages of S. haematobium worms to praziquantel (PZQ) was examined. Schistosoma haematobium-infected hamsters were classified into 4 groups and were treated at day 35, 55, 75, and 95 postinfection (PI), respectively. Each group was subdivided into 3 subgroups. Two of them were treated orally with PZQ (300 mg/kg or 500 mg/kg divided equally on 2 consecutive days), and the third group was left without treatment. Treated groups were killed 20 days posttreatment. Infection with S. haematobium became patent 73 days PI; tissue egg load and worm fecundity were higher at 95 days and maximal 115 days PI, with an oogram pattern comparable to that in Schistosoma mansoni infection. In the liver, small cellular granulomas were observed 75 days PI, with preponderance of CD4+ T-cell phenotypes. In the urinary bladder, only submucosal focal Brunn's-nest formation and angiogenesis without typical granulomas were observed. Ninety-five and 115 days PI, confluent granulomata with multiple eggs in the center were observed in the liver and urinary bladder, with a preponderance of CD8+ positive T cells in the liver and hyperplasia of the urinary bladder epithelium with cystitis cystica and papillae formation. One hundred percent worm eradication was recorded with the higher dose of PZQ in animals treated 75 and 95 days PI. In conclusion, in spite of the long prepatent period of the Egyptian strain of S. haematobium, sensitivity to PZQ was recorded soon after infection. Granulomata were similar to those of S. mansoni in the livers and urinary bladders, but they were confluent with multiple eggs in the centers, hyperplasia of the urinary bladder urothelium with cystitis cystica, papillae, and Brunn's-nest formation predictive of malignant changes with no hepatocyte dysplasia.

A Novel Mouse Model of Schistosoma haematobium Egg-Induced Immunopathology

“…The hamsters were sacrificed at the point of maximal liver and intestinal Schistosoma egg levels (18 weeks post-infection [74]), at which time livers and intestines were minced, homogenized in a Waring blender, resuspended in 1.2% NaCl containing antibiotic-antimycotic solution (100 units Penicillin, 100 µg/mL Streptomycin and 0.25 µg/mL Amphotericin B, Sigma-Aldrich), passed through a series of stainless steel sieves with sequentially decreasing pore sizes (450 µm, 180 µm, and 100 µm), and finally retained on a 45 µm sieve. Control injections were performed using similarly prepared liver and intestine lysates from age-matched, uninfected LVG hamsters (Charles River Laboratories).…”

Praziquantel: its use in control of schistosomiasis in sub-Saharan Africa and current research needs

“…Evidence from in vitro cultures suggests that S. haematobium is marginally more sensitive to PZQ than S. mansoni (Botros et al 2005(Botros et al a, 2008. There are, however some case reports of S. haematobium infections failing to respond to treatment with PZQ (da Silva et al 2005 ;Alonso et al 2006).…”

Histopathological study on susceptible and resistant Bulinus truncatus snails to infection with Schistosoma haematobium

“…Both at light and electron microscopy, collagen-like fibers are noted at the proximity of hemocytes accumulations. Since no active connective-cell was visualized and no real accumulation of such fibers could be documented in the present study, they are probably pre-existing normal component of the molluscan tissues as suggested by Imbert-Establet et al (1992), Vuong et al (1996) and Botros et al (2008).…”

“…This external layer is often mentioned as the "Paletot". Such two-layered sporocysts have been described at the ultrastructural level (Hussein et al, 2005;Botros et al, 2008). However, the electron micrographs clearly showed that the outer nucleated layer is of host origin.…”