الفهرس 
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Abstract
Schistosomiasis has been classified and prioritized for a global response and targeted for elimination as a public health problem by 2025.
S. mansoni is one of the species of the genus Schistosoma that causes intestinal schistosomiasis in humans as a result of sexual reproduction in the definitive hosts (humans, other primates, rodents) and this type of reproduction allows for parasite genotypic diversity. The phylogeny and evolution within the genus Schistosoma are of great interest and has been a subject to many molecular studies. However, Most of the genetic studies of S. mansoni undertaken so far have relied upon parasite materials obtained by indirect sampling procedures that involve the passage of the parasite through laboratory animals. The intravascular location of adult schistosomes makes them routinely unavailable for study thus hindering population genetic studies of S. mansoni in the human definitive host.
Although S. mansoni is considered a uniform species morphologically, differences between parasite strains or populations have been observed in some biological characteristics such as infectivity, virulence, response to treatment or fecundity.
Understanding the genetic structure of S. mansoni will lead to a better understanding of the variation in natural populations and the transmission dynamics of schistosomes between hosts across geography areas .
In the light of the above, the current work aimed to study the rate of infection and genotype difference of S. mansoni in two different infected populations in Kafr Elsheikh and Behira governorates, Egypt.
One hundred thirty-five participants from Dammanhur, El Behira governorate and one hundred and three from ELshakhloba Kafr Elsheikh governorate in Egypt were recruited for this study after obtaining ethical approval from the Committee of Ethics in Medical Research Institute, Alexandria University. The study concentrated on the performance of Kato katz technique to determine the rate of infection rate the poaitive sample were amplified by PCR and the sequencing of the amplified DNA obtained from PCR for identification of the genotype.
Risk factors were recorded using a predesigned questionnaire: Age and gender of the participants in the two governorates, occupation of the cohort, and water –contact activities.
Stool samples collected in sterile containers from the participants were sent to laboratory of MRI Parasitology Department. The samples were subjected to microscopic examination using Kato Katz thick smear technique.
For molecular analysis, DNA was extracted from microscopic positive stool samples, using the ZYMO fecal isolate DNA (ZYMO, USA), according to the manufacturer’s instructions. The extracted DNA was stored at – 20 ˚C until use. Extracted DNA samples were subjected to PCR analysis for amplifying mitochondrial COX1 gene using JB 3 and JB
4.5 primers, followed by amplicon detection by electrophoresis on agarose gel (1.5%) stained by ethidium bromide the amplicon’s length was 451 bp.
Sequencing was performed using Big Dye TerminatorV3.1cycle sequencing kite (Applied Biological Materials (ABM) Richmond, BC Canada) using forward primer JB3 (200µM, 60 ˚C Tm) to confirm the species identification. Sequencing products were analyzed with a Genetic Analyzer ABI PRISM 3130 (Applied Biosystems). Based upon sequence data, The Phylogenetic tree was constructed using the neighbour-joining analysis of the bioinformatics tools of BioEdit Version 7.0.5.
The data were entered, verified, and analyzed using SPSS software using appropriate statistical tests. Differences and associations were considered statistically significant at P <0.05.After conducting Kato katz thick smear methods for microscopic identification of schistosoma eggs, results revealed the following:
• Shistosomasis was detected in 33 participants out of 238 examined ,with Overall prevalence of S. mansoni infection was 14.1% and 13.9% in Elshakhloba and Damanhur areas respectively.
• The prevalence of infection in males was 20.7% (25 out of 121 males), and femalesrepresent 6.8%(8 out of 117). Males had 3.6 times higher risk for S. mansoni infection.
• Regarding age, middle ages (20- 40ys) prevalence was double than in adolescents (<20ys) and triple than that in older age (>40).
• Regarding occupation, the percentage of participants who had infection and worked as farmers was 51%(17 out of 33) which was significantly higher than other occupation; fishermen represent 24.2%(8 out of 33), student were 21%(7 out of 33) and those who contaced water for domestic propose were 3.1%(1 out of 33). Moreover , the overall exposures to the water source increased the risk 7 times for having infection
• Molecular detection of S.mansoni mitochondrial COX1 gene was successfully amplified by PCR in 13 samples out of 33, positive stool samples identified microscopically .
• Sequencing and phylogenetic analysis revealed that all mt COX1gene isolates are closely related and share the same allele.
• In this work, were a phylogenomic analysis performed to address the two main questions of :
(i) How much is diversity level of S. mansoni in the two governorates
(ii) Whether the different inhabitants with of different occupational activities in the two area share the same genotype with each other and compare the result with the most extensive genetic diversity being found in the old world, particularly in Africa.
In conclusions, S.mansoni genotypes in the two governorates showed no genotype diversity regardless the different occupational activities reported in the two geographical populations.