الفهرس 
Review of Literature
Genomic organization of TTVOnly 14 pages are availabe for public view
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Abstract
End-stage renal disease (ESRD) is a significant problem in almost all countries and the prevalence has increased considerably in developing countries especially those of Middle East. The prevalence of HCV infection among hemodialysis patients is 48% in Egypt. TTV is transmitted parentally, through blood and blood products and also via fecal-oral route. TT Virus infection has been found in 1 - 12% of blood donors reported from different geographical regions. Patients on maintenance hemodialysis (HD) and intravenous drug users are particularly predisposed to bloodborne infections and therefore are suitable populations for clinical and epidemiologic studies on the newly discovered TTV. The absence of a detectable hepatitis B surface antigen (HBsAg) and occasionally other HBV serologic markers has been called occult hepatitis B infection (OBI). The application of highly sensitive and specific tests for HBVDNA has helped to refine the diagnosis of OBI and to promote its emergence as an important clinical entity. The higher incidence and prevalence of HBV infection in HD patients makes vaccination a powerful and desirable tool for prevention of the disease among these high risk individuals.
The aim of this work was: (1) to study the prevalence of hepatitis transfusion transmitted virus (TTV) infection among HD patients. (2) to screen these patients for occult B infection this might be an important source of the continuous HBV infection in HD units and to study the prevalence of occult hepatitis B infection in Egypt and if the infection with the TTV singly or associated with HCV infection. (3) to study the influence of TTV and OBI alone or combined with each other or with HCV on liver enzymes and other biochemical parameters.
OBI among HD patients without HBsAg positive infection was examined by PCR among HD patients and TTV seminested PCR was detected among these patients. The prevalence of TTV and OBI with or without HCV was investigated. Analysis of PCR products of ORF1 gene of TTV on agarose gel electrophoresis and analysis of the HBV surface (S) gene was amplified by a nested PCR, Sexity one hemodialysis patients were collected during the year 2011-2016, together with 16 control subjects, negative for anti- HCV, HBsAg, OBI PCR and TTV. All patients were subjected to biochemical analysis for determination of liver enzymes (AST& ALT), ALP, urea, creatinine, uric acid, phosphorus, calcium, sodium, potassium, hemoglobin, WBCꞌs and platelet. The HD patients were divided into six groups where, G1: TTV group, G2: OBI group, G3: TTV and HCV group, G4: HCV group, OBI and coinfected with other viruses TTV and HCV group, G5: OBI and coinfected with other viruses TTV and HCV group, G6: non (OBI/TTV/HCV) group. The distribution of the detected viruses were in G1 (13.1%), G2 (21.3%), G3 (14.8%), G4, (26.2%) and G5 (11.5%). In G6, the viruses OBI, TTV and HCV were absence in 13.1% among HD patients.TTV+HCV co-infection, indicated by the presence of TTV DNA and HCV RNA, was observed in 14.8% with HD patients.
No statistical difference was found in all HD groups in AST and ALT when compared with contrl group. A highly significant increase of urea, creatinine, uric acid and ALP were found in all groups when compared with control group in HD patients. K and P showed a significant difference in all groups when compared with control group in HD patients. Hb and platelet showed a highly significant decrease in all HD patients when compared to control group. Na and Hb showed a highly significant decrease in the group of OBI compared with –ve HBV patients among HD patients.
from the present study, we concluded that, The nosocomial risk factors play an important role in TTV alone and mixed with HCV infections among patients on haemodialysis, these factors are related to dialysis machines and dialyzers which include dialyzers membranes and haemodialysis ultrafiltrate,reprocessing of dialyzers, and dialysis machines. Also, the importance of identify individuals with OBI in dialysis units as those patients may be potential sources of HBV nosocomial transmission. Whether all individuals undergoing dialysis should be submitted to HBV-DNA screening or whether this test should be restricted to high risk populations still has not been ascertained.
Recommendation: Because prevention is the first line of defense against blood borne pathogens especially viral hepatitis infection and is much more cost-effective than treatment, prevention should be the main goal of current efforts to break the vicious cycle of this infection.
In Egypt, government should provide more support for application of infection control policies regarding the vaccination of high-risk groups, such as HD patients and medical staff, as the cost of treatment is much higher than the cost of vaccination. Also, the accurate prevalence of OBI in Egypt among high-risk groups especially HD patients is not well known and can only be definitively determined by giving more attention to large, national epidemiological studies.