الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
Hepatitis E virus (HEV) infection results in hepatitis E, an acute and self-limited disease. The virus is transmitted in a faecal–oral manner and is a major cause of viral hepatitis in much of the developing world, where it causes rampant sporadic infections and large epidemics. A curious feature of hepatitis E is the unusually high rates of mortality that are observed in pregnant women, in whom the disease is exacerbated by the development of fulminant liver disease. HEV is a spherical, nonenveloped virus that is approximately 32-34 nm in diameter. The HEV gemone is a single- stranded, positive sense, polyadenylated RNA molecule, approximately 7.5 kilobases in length. Three open reading frames (ORFs) have been identified; ORF1 codes for non-structural proteins responsible for replication of the viral genome, ORF2 codes for structural proteins, including the capsid protein, and ORF3 codes for a protein appears to be involved in virus-host interaction. On the basis of structural and physiochemical properties HEV has been classified in family calciviridae, genus calcivirus. However, its genome organization more closely resembles that of rubella virus and plant furoviruses than that of calciviruses. Sequence analysis of the genomes of several HEV strains from different geographical areas showed that HEV has at least four recognized genotypes, but has only a single serotype. In the past diagnosis of HEV was by exclusion of other types of viral hepatitis. However, it has recently become possible to detect HEV infection by using an enzyme-linked immunosorbent assay (ELISA) based on cloned recombinant HEV antigens to detect anti-HEV IgM and anti-HEV IgG antibodies. The aim of this study was to determine HEV infection among cases of acute viral hepatitis in Alexandria. The study was carried out on 100 patients of both sexes admitted to fever hospitals with clinical diagnosis of acute hepatitis. All relevant information was collected from each patient including personal data (e.g.: age, sex, occupation, etc…) as well as health data (e.g.: jaundice, fever, history of blood transfusion, etc…). Three ml of intravenous blood was collected aseptically from each patient and tested for the presence of anti-HEV IgM and anti-HEV IgG antibodies using ELISA techniques. To evaluate the liver function, sera were also tested for ALT level by kinetic photometric technique. Among 100 acute hepatitis patients IgM anti-HEV was detected alone in 16 patients, IgG anti-HEV was detected alone in 30 patients, while both were detected in 6 patients. Accordingly, the prevalence of HEV infection in the studied group was 52 (Those having any marker for HEV), while the incidence of HEV infection was 22 (Those having anti-HEV IgM). These results are relatively high and indicate that HEV is a major cause of enterically transmitted non-A, non-B hepatitis in Alexandria. Among the studied group, it was found that the males are at higher risk for acquiring HEV infection than females. This sex related difference in exposure to HEV is probably because of social habits rather than genetic predisposition. In this study it was found that the highest incidence of anti-HEV IgM antibodies was in the middle age group. This could result from increased exposure to high-risk environment through work and travel, sexual contact, or from increased exposure secondary to increased volume of ingested food and water compared with infants and children. In this study, it was observed that the prevalence rate of HEV infection among hepatitis patients was increased by age. These results may reflect failure of young children to mount a brisk anti-HEV response when compared with adult and the sporadic transmission of the virus that accumulates over age, which is consistent with the predominantly subclinical nature of the infection, the short period of infectious viremia and consequently limited pool of HEV infection in the community. In the studied group nearly half of the patients with HEV infection had no past history of jaundice. And, the presence of family history of jaundice in patients with HEV infection was significantly low. These results could be explained by the subclinical pattern of the disease especially during childhood. Since, like HAV, HEV is generally transmitted by the faecal-oral route, it was found that its prevalence rate is relatively lower than HAV. This could be related to the epidemiology of HEV and/or to technical limitations in its detection. However, the variable persistence of IgG anti-HEV makes it difficult to determine accurately the frequency of exposure in any population and raise the possibility of reinfection after disappearance of this antibody. Lastly, further studies are needed to determine to the sensitivity and the specificity of the available ELISA to reach an accurate diagnosis of HEV infection.^lEng