Comparison of the Teesdale glass sandwich and Kato-Katz techniques for the diagnosis of Schistosoma mansoni: a double-blind study.

In a double blind study, the Teesdale glass sandwich and Kato-Katz techniques were compared for the diagnosis of Schistosoma mansoni. From each of five stool specimens, six slide preparations were made by each method, and each slide was read independently by two readers. Examination of the differences in the number of eggs per slide by Analysis of Variance (ANOVA) showed no significant differences between methods, readers, or slides prepared from the same specimen at the 90% level of significance.

Schistosomiasis in Malawi--a review.

Prevalence data for schistosomiasis in Malawi, collected in recent years, indicated that the infection, especially Schistosoma mansoni is far more widespread than was previously thought. S. haematobium is highly prevalent in the south, while S. mansoni predominates on the Central Plateau. Both infections occur with moderate to high intensity along the lakeshore plain. Despite the high prevalence, reports of morbidity due to the infection are fewer than might be expected.

Egg count variability and sensitivity of a thin smear technique for the diagnosis of Schistosoma mansoni.

Variation in daily egg counts, and in counts for samples of the same stool, was investigated in children with Schistosoma mansoni and Ascaris lumbricoides infections, using a thin smear technique. The results indicated that counts vary according to the stool consistency; drier stools from the same person producing up to seven times greater counts than wet ones. The sensitivity of the technique was tested in schoolchildren living in an endemic S. mansoni area, and found to detect all infections with intensities of greater than 50 eggs per gram of stool, after examination of only one slide containing 40mg stool. The sensitivity varied with the intensity of infection. The relevance of these findings to diagnosis in field situations is discussed.

Long-term efficacy of single-dose oral treatment in schistosomiasis haematobium.

A two-year follow-up was conducted in children who had been the subjects of a six-month double-blind trial in the single-dose treatment of Schistosoma haematobium infection. The trial had assessed therapeutic efficacy of three oral preparations-praziquantel 40 mg/kg, metrifonate 10 mg/kg, and the 'combination' (concurrent niridazole 25 mg/kg and metrifonate 10 mg/kg administration). Reduction in urinary egg excretion remained high up to follow-up at two years, based on a comparison of pre- and post-treatment geometric mean counts-praziquantel 96.9% (n = 96 at six months, 51 at two years); the 'combination' 93.9% (n = 97 at six months, 48 at two years); and metrifonate 90.3% (n = 92 at six months, 49 at two years). The differences in percentage reduction were not significant (p greater than 0.1). However, a significantly greater reduction in egg output was produced by praziquantel (81.7%) and the 'combination' (82.5%) than by metrifonate (54.2%), on comparing pre- and post-treatment arithmetic mean counts (p less than 0.01). A significantly smaller percentage of subjects were excreting greater than or equal to 125 ova/10 ml urine two years after treatment with praziquantel (10.3%), compared to treatment with the 'combination' (25.7%) and metrifonate (35.8%) (p less than 0.01). The cure rate was significantly higher in the praziquantel group (47.4%) compared to the 'combination' (24.7%) and metrifonate (17.4%) groups, for the six to 24-month follow-up period (p less than 0.001). The pattern and level of transmission had contributed to the long-term efficacy recorded in this study.

Single dose oral treatment in urinary schistosomiasis: a double blind trial.

A double blind trial of three oral preparations given in single doses for the treatment of Schistosoma haematobium infection was carried out in schoolchildren; selection was biased towards those who excreted large quantities of eggs. Praziquantel 40 mg/kg was the most effective drug giving a greater than 97% reduction in egg output six months after treatment; combined treatment with niridazole 25 mg/kg and metrifonate 10 mg/kg gave a reduction of greater than 92% and metrifonate 10 mg/kg alone a reduction of greater than 86%. Fewer children continued to have moderate to heavy infections (excretion greater than 124 ova/10 ml urine) six months after treatment with praziquantel (5%) and the combined regimen (7%) than with metrifonate (16%). Though our findings show that praziquantel appears to be the most effective and convenient drug available for individuals with S haematobium infection, the combined regimen is a cheaper alternative for treatment where cost is important and parasitological cure not an essential objective.

Studies on the enzyme linked immunosorbent assay (ELISA) test for Schistosoma mansoni infections.

Extensive studies of the use of the ELISA test for the detection of antibodies in Schistosoma mansoni infections are described. A method has been evolved for the determination of the optimum value for the reference serum endpoint. In chimpanzees infected with S. mansoni a crude egg antigen detected antibodies earlier in the infection than did a worm antigen and was generally more reactive. The ELISA test, using the egg antigen, has been applied to sera from populations infected with S. mansoni, with other human schistosomes, or with helminth infections other than schistosomiasis. The ELISA test was as sensitive as the IFAT and CFT, but more specific. However, many cross-reactions occurred in infections with other human (and with animal) schistosomes, although to a lesser extent with other helminths. In surveys in the Sudan the use of blood collected on absorbent paper was only slightly less sensitive for the detection of antibodies than sera, and this technique showed that the prevalence of infection was higher than that measured by stool examination alone. Possible future developments are discussed with a view to improving sensitivity and specificity both for clinical and epidemiological work.

Metrifonate trial in the treatment of various presentations of Schistosoma haematobium and S. mansoni infections in the Sudan.

The effect of metrifonate (Bilarcil Bayer) on Schistosoma haematobium and S. mansoni infections was studied in 174 patients near Khartoum. A high cure rate was obtained in S. haematobium infections, but anthelmintic efficacy was minimal in patients passing S. mansoni eggs in their stools. There was, however, a marked reduction of egg output in patients passing S. mansoni eggs in urine. This suggests that the site of infection in man, rather than the species of parasite, renders the parasite more susceptible to metrifonate. The significance of this and the possibility that these results further clarify the mode of action of metrifonate are discussed.

Comparison of the Bell technique, a modified Kato thick smear technique, and a digestion method for the field diagnosis of schistosomiasis mansoni.

A modification of the Kato thick smear technique, the Bell filtration technique, and a digestion method were investigated to determine the relative merits of each for the detection of schistosome eggs in human faecal samples. The modified Kato technique was the method of choice because it was sensitive, simple to perform, and suitable for field use. The Bell filtration technique was equally sensitive in detecting light infections, but was more tedious and more complicated to perform than the thick smear technique.

A simple thick-smear technique for the diagnosis of Schistosoma mansoni infection.

A smear technique is described in which thick glass coverslips are substituted for cellulose acetate film soaked in glycerine as used in the Kato technique for stool examination. Estimates of the sensitivity and applicability of this technique for Schistosoma mansoni infections indicate that it compares favourably with the Kato technique, especially for field use.