Molecular approach for detecting early prepatent Schistosoma mansoni infection in Biomphalaria alexandrina snail host.

The present study aimed to evaluate a polymerase chain reaction (PCR) assay used for detection of Schistosoma mansoni infection in Biomphalaria alexandrina snails in early prepatent period and to compare between it and the ordinary detection methods (shedding and crushing). Biomphalaria alexandrina snails are best known for their role as intermediate hosts of S. mansoni. DNA was extracted from infected snails in addition to non-infected "negative control" (to optimized the efficiency of PCR reaction) and subjected to PCR using primers specific to a partial sequence of S. mansoni fructose-1,6-bus phosphate aldolase (SMALDO). SMALDO gene was detected in the infected laboratory snails with 70, 85, and 100 % positivity at the 1st, 3rd, and 7th day of infection, respectively. In contrast, the ordinary method was not sensitive enough in detection of early prepatent infection even after 7 days of infection which showed only 25 % positivity. By comparing the sensitivity of the three methods, it was found that the average sensitivity of shedding method compared to PCR was 23.8 % and the average sensitivity of crushing method compared to PCR was 46.4 % while the sensitivity of PCR was 100 %. We conclude that PCR is superior to the conventional methods and can detect positive cases that were negative when examined by shedding or crushing methods. This can help in detection of the areas and times of high transmission which in turn will be very beneficial in planning of the exact timing of the proper control strategy.

Geohelminths distribution as affected by soil properties, physicochemical factors and climate in Sharkyia governorate Egypt.

Soil-transmitted helminths are mainly a group of parasitic nematodes causing human infection through contact with parasite eggs or larvae; they survive in the warm and moist soil of the tropical and subtropical countries. This study was carried out in Sharkyia governorate from October, 2011 to October, 2013, to correlate between the prevalence and distribution of these parasites in the soil and the physicochemical factors affecting the examined samples of the soil. One hundred and twenty samples of different types of soil (clay, silt, sand) from different localities were collected and examined. Diagnosis of geohelminths was confirmed by the recovery of their eggs and larvae with other protozoa by different parasitological methods. The modified baermann method was found to be more efficient in detection of geohelminths larvae than charcoal culture method. Among the examined sites geohelminths were much more numerous in the soil of rural areas especially in the spring and summer seasons, while the contamination of canal banks by geohelminths was the worst (80 %). An insignificant correlation was reported between the soil texture and the number of positive samples in the examined areas while the relationship was directly proportional among (moisture, PH, organic). It appeared that the most common geohelminthic stage was Toxocara spp. eggs besides other types of protozoa especially Balantidium coli cysts. This suggests that factors other than soil texture are important in the prevalence of geohelminths in the soil e.g. temperature, moisture, PH and organic matter. So, to change some of these factors in a trial to control geoparasites transmission but with keeping the environment should be tried. These results also open the way to further studies to highlight the mutual affection between inhabitants of these sites and the prevalence of these geoparasites.

Studies on the role of tumor necrosis factor- alpha (TNF-α) in hepatocytes induced apoptosis in vaccinated, Schistosoma mansoni-challenged mice.

Tumour Necrosis Factor-alpha (TNF-α) plays a complex role in pathophysiological changes caused by schistosomiasis in the liver cells as induced apoptosis. So, The highlighted experimentally the role of TNF-α in hepatocytes apoptosis, using that as an assessment of the efficacy of antischistosomal vaccination by mixed crude antigens preparations [Cercarial antigen preparation (CAP) + soluble worm antigen preparation (SWAP) + soluble egg antigen(SEA)] by parasitological, histo-pathological and histochemical studies using Feulgen stain of hepatoytes DNA, a serological study also of serum TNF-α level by ELISA. Fifty two laboratory bred Albino male mice, were used in this study. They were classified into four groups (13 mice in each group), G1: normal control, G2 as infected control while G3 supported by Freund's Adjuvant (F. Adj) then infected and G4 vaccinated with combined antigens (CAP, SWAP and SEA) + F. Adj, then infected. Mice were sacrificed by cervical dislocation 9 weeks post infection, parasitological (Kato-Katz thick smear for egg count), histopathologial {haematoxylin and eosin (H&E) staining of hepatic sections}, histochemical (feulgen staining of hepatocytes DNA) and ELISA to estimate serum TNF-α level were performed. The data showed that vaccination with combined antigens showed protective effect on vaccinated then Schistosoma challenged mice, hepatocytes induced apoptosis was directly proportional with the TNF-α serum level, and the protection degree of potential combined vaccine was inversely proportional with serum TNF-α level and induced apoptosis.