Hepatic amoebiasis in immunodepressed mice

The effects of immunodepression on intestinal amoebic lesions produced by Entamoeba histolytica were studied in inbred mice of the C3H/mg strain. Immunodepression was induced in two ways by giving (i) cyclophosphamide and (ii) anti-mouse lymphocyte serum. On immunodepression with the latter, although there was no difference in the degree of macroscopic intestinal damage, all five surviving immunodepressed mice showed hepatic lesions. It is noted that these had a striking histological resemblance to human and hamster lesions in hepatic amoebiasis.     

Immunoelectrophoresis test for amoebiasis

Haemagglutination and immunoelectrophoresis tests were investigated to find which was more suitable for the immunodiagnosis of amoebiasis. Both tests were positive in more than 90% of sera from patients with amoebic liver abscess. With serum from blood donors and patients with other diseases a much lower percentage of positives was given by the immunoelectrophoresis test, showing that this test had a closer correlation with clinically important disease.     

Cell-mediated immunity in hepatic amoebiasis

Cell-mediated immunity (CMI) was measured by blastic transformation of peripheral blood lymphocytes in 26 patients with amoebic liver abscess (ALA) and matched control subjects with no demonstrable clinical amoebiasis. During active disease, the mean mitogenic response, measured by the stimulation index of the patients' lymphocytes to Entamoeba histolytica antigen, was increased (mean +/- SD: 25.98 +/- 46.62 compared with 11.27 +/- 21.39), whereas that to phytohaemagglutinin (PHA) was reduced (54.80 +/- 56.26 compared with 111.70 +/- 70.61). Both these results were statistically significant (P less than 0.01); they do not, however, appear to be due to a quantitative defect in T-cell numbers, as both total peripheral lymphocytes (3332 +/- 1450 cells/microliters compared with 2447 +/- 531 cells/microliters) and T-cells (2652 +/- 1128 cells/microliters compared with 1908 +/- 386 cells/microliters) were significantly elevated in the patients (P less than 0.01). When these tests were repeated two months later in 12 cured patients they were found to be comparable to those of the control subjects. The results indicate that there is a transient cellular sensitization to amoebic antigen together with an increase in T-lymphocytes and an impairment of the mitogenic response of lymphocytes to PHA. The significance of these findings is discussed.     

Safety and efficacy of diphetarsone in the treatment of amoebiasis, non-pathogenic amoebiasis and trichuriasis

Eighty-nine patients infected with Entamoeba histolytica, non-pathogenic amoebae or Trichuris trichiura were studied prospectively to determine the safety and efficacy of diphetarsone therapy. An additional 75 patients were studied retrospectively to assess further the efficacy of diphetarsone in the treatment of E. histolytica cyst passers. Side effects were noted in 9% and included gastrointestinal upset, lightheadedness and headache. Transient liver function abnormalities were recorded in 5.6%. diphetarsone was completely effective in the treatment of Dientamoeba fragilis, Entamoeba hartmanni, Iodamoeba buetschlii and Trichuris trichiura. 99% of the patients with E. histolytica, 97% of those with E. coli and 98% of those with Endolimax nana were cured.     

Nitazoxanide in the treatment of amoebiasis

Amoebiasis is a significant cause of morbidity worldwide and is the third leading cause of death from parasitic diseases. This study evaluated nitazoxanide, a thiazolide anti-infective, in the treatment of intestinal and hepatic amoebiasis. Prospective, randomised, double-blind, placebo-controlled studies were conducted in outpatients with intestinal amoebiasis from the Nile Delta of Egypt. Nitazoxanide was administered twice daily for 3 days at doses of 500mg (age > or =12 years), 200mg (age 4-11 years) or 100mg (age 1-3 years). Seventeen adults hospitalised with hepatic amoebiasis were treated with 500mg nitazoxanide twice daily for 10 days. Four days after completion of therapy, 32 (94%) of 34 nitazoxanide-treated patients with intestinal amoebiasis resolved symptoms compared with 15 (50%) of 30 patients who received placebo (P<0.001). Thirty-two (94%) of 34 nitazoxanide-treated patients were free of Entamoeba histolytica in two post-treatment stool specimens compared with only 13 (43%) of 30 patients receiving placebo (P<0.0001). All patients with hepatic amoebiasis responded to nitazoxanide therapy. Nitazoxanide is effective in treating invasive intestinal amoebiasis and in eliminating E. histolytica colonisation of the intestinal tract. Further studies are warranted in patients with hepatic amoebiasis.