Current status of sensitivity to praziquantel in a focus of potential drug resistance in Egypt.

A decade ago, a study revealed that praziquantel (PZQ) failed to cure 1.6% of those with intestinal schistomiasis in five villages of the Nile delta region. The recommended dosage of PZQ is a single 40 mg/kg oral dose, and each of these patients continued to pass viable Schistosoma mansoni eggs despite three successive doses at or above this level. The eggs passed by these uncured villagers produced adult worms that were, in most cases, significantly less responsive to PZQ in vitro. This report investigates the current sensitivity of S. mansoni infections to PZQ after 10 years of therapeutic pressure in the same villages, testing the hypothesis that the number of drug failures would have increased as continued drug pressure selected for worms with diminished sensitivity to PZQ. The data show that these villages have experienced a significant decrease in the prevalence and intensity of S. mansoni infections, with present infection rate of 10.9%, compared with 25.1% in 1994. The first treatment resulted in normal range of cure rates, between 73.8 and 92.3% in each of the five villages in the study. After three successive doses (40, 40, and 60 mg/kg, the same treatment protocol applied a decade ago) there were no uncured patients remaining in the study. This shows that there has not been an increase of drug failure, despite 10 years of therapeutic pressure in these villages where there had been resistant infections and worms with decreased response to PZQ.

Epidemiology of Schistosoma mansoni infection and its relationship to snail distribution in a village at the Nile bank south to Cairo.

The relationship between epidemiology of S. mansoni infection and snail distribution at a village, related to Guiza Governorate and lies south to Cairo, was investigated. A systematic random sample of houses was selected. All inhabitants of the houses were invited to share in the study. The Number examined was 704. Urine and stools were examined using Nucleopore filtration and standard Kato-Katz techniques, respectively. Snail collection was done from 35 sites along the water bodies related to the village. Snails collected were examined by cercariae shedding under light. Snail differentiation was done. The results showed that the prevalence of Schistosoma mansoni human infection was 25.1 % and GMEC was 2.4 +/- 5.5. Schistosoma haematobium infection was zero percent. Biomphlaria alexandrina snail infection rate was 3.7% with density equal 0.5 +/- 1.3. Bulinus truncatus snail infection rate was zero percent. The pattern of S. mansoni human infection was closely related to snail distribution and infection. Presence of a hybrid species of B. alexandrina and B. glabrata may explain the epidemiological pattern found in the studied village.

Incidence of cryptosporidiosis in immunodeficient cancer patients in Egypt.

A coproprotozoal study was carried out on 63 patients suffering from malignancy. The majority had cancer of haemopoietic system. All patients were under chemotherapy and included: Group A (33 children) and Group B (30 adults) of whom 20 immunocompetent diarrhoeic patients of matched age and sex were considered as controls. Stool samples were examined by merthiolate iodine-formaldehyde concentration technique (MIF). Modified Zeihl-Neelsen (ZN) stain was performed for Cryptosporidium oocysts. Detection of Cryptosporidium coproantigen by enzyme-linked immunoassay test (Ridascreen test), was used. Immunoglobulins (IgG, IgM, IgE & IgA), C3, C4 and CD4:CD8 ratio, were measured. According to their levels 25 out of 63 patients had both humoral and cellular immunodeficiency. The incidence of Cryptosporidium in cancer patients was 23.8%, while it was 37.7% and 91% in children and adults immunodeficient patients, respectively. ZN stain was able in diagnosed Cryptosporidium in 13 out of 35 immunodeficient cases while ELISA detected only 11 cases. Cryptosporidium infection in immunodeficient cancer patients had significantly more frequent and prolonged duration of diarrhoea than in negative ones.

Upgrading of Kato-Katz technique for diagnosis of S. mansoni infection in rural Egypt.

Processing of the same stool samples was done using standard Kato-Katz (KK) technique with 41.7 mg of stools and one of the three modifications. These included KK technique using a higher concentration of glycerin (one and quarter, usual one) for preparation, or another stain (negrosin-eosin), with a specified formula, instead of the standard malachite green, or processing a smaller volume of stools (20mg). The results showed that, using cumulative infection rate from the two comparable tests as the reference, KK with higher concentration of glycerin was more sensitive than standard KK (sensitivities 77.6% and 61.2%. respectively). Using negrosin-eosin stain showed higher sensitivity (75.0%) in relation to standard KK technique (70.8%). Kato-Katz with higher concentration of glycerin showed the same sensitivity as KK with negrosin-eosin stain (85.7%) in relation to others. All comparisons showed statistically insignificant differences ((P>0.5). Using 20 mg of stools showed very low sensitivity in relation to standard KK technique (57.9% & 100.0% respectively). The statistical difference was highly significant. All specificities were 100%. Other screening indices showed the same trend of sensitivities. Degree of microscope clarity was optimal with higher concentration of glycerin. Negrosin-eosin showed better visualization of ova than the standard KK. All modifications took only an hour after processing to be examined. KK technique used with any of these modifications, is simple, inexpensive. use of either a higher concentration of glycerin or negrosin-eosin stain and recommended for both field studies and primary health care settings.