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Murine schistosomiasis is usually associated with hepatic granulomatous lesions together with high serum and granuloma angiotensin converting enzyme (ACE) activity. Praziquantel (PRZ) which is known to reduce granuloma size was studied to show whether this effect is related to changes in ACE activity. Furthermore, captopril was studied to show whether by inhibiting ACE activity, the drug could also affect granuloma size. PRZ, captopril, and their combination led to significant reduction in liver granuloma. However, in normal mice, captopril was shown to increase rather than decrease serum ACE. The decrease in ACE activity by PRZ was correlated with its curative effect in infected mice. However, in experimentally induced pulmonary granulomata, the drug reduced granuloma size without affecting ACE activity of either serum or granuloma. It may be concluded that reduction in ACE activity may be beneficial as far as diminution of granuloma size is concerned and irrespective of whether there is an active infection or not. The possible use of Captopril as an antihypertensive in bilharzial infections associated with hypertension would probably not adversely affect the granulomatous lesions.

The schistosomicidal efficacy of praziquantel (2 × 500 mg/kg), oxamniquine (1 × 100 mg/kg) and combined one-third the curative dose of each of them (333 mg/kg praziquantel+33 mg/kg oxamniquine), were correlated to gonadal steroid hormonal changes and state of disease immunopathology, in mice infected with 100 Schistosoma mansoni (S. mansoni) cercariae. Maximum efficacy recorded with combination regimen particularly 4 weeks after treatment, was accompanied by maximum reduction in granuloma volume (65%), least fall in testosterone level (−56·2 and −60·2% in male and female mice respectively) and increased progesterone level (+ 33 · 9 and + 81 · 5% in male and female mice respectively). These findings revealed a potentiated effect of combination therapy on mature infection and the possible involvement of gonadal steroid hormones in affecting the efficacy of schistosomicidal drugs and state of disease immunopathology.

Cytophotometric measurement of the effect of praziquantel (500 mg/kg for 2 days) versus hycanthone (60 mg/kg for 3 days) on hepatocyte nuclear deoxyribonucleic acid (DNA) content was evaluated in Schistosoma mansoni infected mice. Drugs were given 8 weeks post-infection and repeated weekly for 4 weeks. DNA values of infected untreated control and infected drug treated groups were related to the median and upper diploid DNA values of normal control. Schistosoma mansoni infection per se did not change the hepatocyte DNA content, yet aneuploidy was 16.7%. Praziquantel did not result in significant change of DNA content or ploidy, while hycanthone resulted in marked significant increase of DNA content (328.9%) and aneuploidy (100%), compared to infected untreated control. Histopathological examination revealed hyperchromatic nuclei with mitosis in the hepatocytes of hycanthone treated mice, but not in praziquantel treated animals. These DNA changes were found to correlate with the reported safety of praziquantel and the carcinogenicity of hycanthone.

Granulomata formed in the liver or lung of man and animals infected with schistosomiasis are common manifestation of an inflammatory delayed hypersensitivity reaction. Non-steroidal anti-inflammatory drugs (NSAIDs) (tiaprofenic acid and piroxicam) have been used alone and as adjuvants to praziquantel in treating pulmonary granulomata induced in mice by injecting them intravenously with S. mansoni eggs. The size of the granulomata, as well as some immunological parameters, have been measured at the end of treatment. Both anti-inflammatory drugs effectively reduced the size of lung granulomata in a dose-dependent manner. The immediate skin reaction and, to a lesser extent, the delayed reaction were reduced by these drugs. Tiaprofenic acid, but not piroxicam, reduced the percent macrophage migration inhibition in vitro. The combined therapy of either of the drugs with praziquantel did not result in an additive effect.

Mice infected for 45 days with 120 Schistosoma mansoni cercariae and treated with levamisole (25 mg/kg subcutaneously) have more efficient acquired immunity when challenged with 240 Schistosoma mansoni cercariae the same day of treatment (97.7% # 87.7% in infected challenged controls). In praziquantel-treated mice (500 mg/kg for 2 days orally), the reduction in the percent resistance (45.5%) was accompanied by a significant diminution in the size of granuloma, delayed foot pad swelling and granuloma proportionate T-helper cells number. Levamisole when given two weeks post praziquantel treatment and with the challenge infection increased the percent resistance to 79.2%. The increase in percent resistance recorded in mice receiving both praziquantel and levamisole was accompanied by restoration of granuloma size, delayed foot pad swelling and granuloma proportionate T-helper cells number to infected challenged untreated control values. Results reveal-beside efficacy of levamisole as immunoregulant in schistosome immunity--a possible role for the granuloma as a T-cell mediated response in maintenance of immunity.

The effect of specific chemotherapy on hepatic fibrosis was studied in Swiss albino mice infected with Schistosoma mansoni. The effect of treatment with praziquantel at 8, 12, and 20 weeks postinfection on fibrosis was assessed by determination of total hepatic collagen content, ratio of type III/I + III collagen, granuloma volume, and histopathological examination of liver section. Total collagen content was reduced in mice treated at the 8th week of infection compared to respective infected controls. The ratio of type III/I collagen was within normal limits. The decrease in collagen deposition was not observed when treatment was given 12 or 20 weeks postinfection. Early specific treatment of schistosomiasis may be important in the therapeutic approach to the control of morbidity in schistosomiasis.The effect of specific chemotherapy on hepatic fibrosis was studied in Swiss albino mice infected with Schistosoma mansoni. The effect of treatment with praziquantel at 8, 12, and 20 weeks postinfection on fibrosis was assessed by determination of total hepatic collagen content, ratio of type III/I + III collagen, granuloma volume, and histopathological examination of liver section. Total collagen content was reduced in mice treated at the 8th week of infection compared to respective infected controls. The ratio of type III/I collagen was within normal limits. The decrease in collagen deposition was not observed when treatment was given 12 or 20 weeks postinfection. Early specific treatment of schistosomiasis may be important in the therapeutic approach to the control of morbidity in schistosomiasis.

The effects of praziquantel on cellular and humoral immune responses were studied in Swiss Albino mice and compared with the effects of potassium antimony tartrate. The experimental animals were antigenically primed by intravenous injection of Schistosoma mansoni eggs; the test drugs were given one day before egg injection and their effects monitored 16 days later. The size of the experimentally-induced pulmonary granulomata, immediate and delayed antigen-induced foot pad swelling, in vitro macrophage migration inhibition and the percentage of lymphocytes forming antibody and complement-dependent rosettes with erythrocytes (% EAC-R) were parameters used to assess the effect of the drugs. Praziquantel suppressed the size of pulmonary granulomata and the immediate and delayed foot pad reaction. Macrophage migration inhibition and the percentage of lymphocytes forming EAC-rosettes were not significantly affected. Tartar emetic was more effective as an immunosuppressant drug in these tests than praziquantel.

Combined low doses of praziquantel and oxamniquine were tested against different stages of Schistosoma mansoni in infected Swiss albino mice. The effect of combination therapy ( 1 3 the curative dose of praziquantel plus 1 3 the curative dose of oxamniquine) was compared with the effect of each drug alone, in reduced or full dose. Comparison with infected untreated controls was also made. Drug effects were evaluated on different growth stages of schistosomes by administering the drugs 24 h before infection and 4 h, 1, 2, 3, 4 and 5 weeks after infection. Animals were killed 8 weeks after infection. Worm burden, distribution, tissue egg load and oogram pattern were used in assessing drug efficacy. A potentiating effect was observed in animals receiving combination therapy. The combination regimen was most effective 4 h after infection, producing 96% worm reduction; eggs were not detected in the liver or intestine. Five weeks after infection the same regimen resulted in 98% reduction in the tissue egg load.

This trial investigated the anti-schistosomal activity of mirazid in comparison with that of praziquantel in Schistosoma mansoni-infected Egyptian patients. The sample population was composed of 1,131 individuals (459 school children and 672 household members). Screening for S. mansoni was conducted using the standard Kato Katz technique. Four slides from a single stool sample were examined before treatment, and four slides per sample from stool samples obtained on three consecutive days were examined post-treatment. All positive eligible subjects were randomly assigned into two groups, the first received mirazid at a dose of 300 mg/day for three consecutive days, and the second received praziquantel at a single dose of 40 mg/kg. All treated subjects were examined 4-6 weeks post-treatment. Mirazid showed low cure rates of 9.1% and 8.9% in S. mansoni-infected school children and household members, respectively, compared with cure rates of 62.5% and 79.7%, respectively, in those treated with praziquantel. Therefore, we do not recommend mirazid as an agent to control schistosomiasis.