How is Hepatitis E Diagnosed?
Diagnosing Acute Cases
Hepatitis E Virus (HEV) infection diagnosis is quite a complex process and clinically cannot able to differentiate from other viral infection. During the outbreak (high endemicity) most of the patients with Hepatitis E infection present with acute viral hepatitis that is characterized by a fever, malaise, fatigue, nausea, and vomiting. After a few days, the onset of symptoms like dark urination and jaundice occur, which last for a one or two weeks. Most of the cases recover spontaneously, but some may develop into acute liver failure condition which is poorly understood. The disease predominantly occurs in young people between 25 to 40 and in pregnant women, it is quite serious which may develop to the liver failure condition. Some patients present with acute-on-chronic liver failure, which suggests HEV infection superimposed on a pre-existing chronic liver disease.
Clinical Diagnosis of Chronic Cases
Chronic infection with Hepatitis E has been noted in low endemicity regions. It is common among patients who are recipients of an organ transplant and who are receiving immunosuppressive drugs (AIDS and Cancer patients). These syndromes are also indistinguishable from those caused by other hepatitis viruses and nonviral causes of liver injury.
Laboratory Diagnosis – Detection of Specific IgM Antibodies
Absolute diagnosis of hepatitis E infection in patients is usually done based on the detection of specific IgM antibodies to the virus in a person’s blood. This is usually adequate in areas where the disease is common. Diagnosis of current hepatitis E and previous exposure to HEV depends primarily on detecting anti-HEV antibodies belonging to IgM and IgG isotypes in the serum.
Laboratory Diagnosis – Biochemical and Radiological Tests
A serious of changes occurs in biochemical parameters in patients with HEV infection. It includes bilirubinuria, raised serum levels of bilirubin that is predominantly conjugated, markedly increased serum levels of alanine and aspartate aminotransferases and, in some patients, a modest increase in serum levels of alkaline phosphatase.
Patients with severe liver injury have abnormal coagulation test results and reduced serum levels of proteins that are synthesized in the liver, such as albumin and prothrombin.
Ultrasonography, CT, and MRI techniques can help to identify a liver condition that is triggered by viral hepatitis. Examining the liver nodularity with these imaging processes enables the diagnosis of an underlying chronic liver disease in patients who present with acute-on-chronic liver failure.
Using immune electron microscopy, HEV particles have been found in fecal specimens from patients with acute hepatitis E in endemic regions and in samples from animals that were infected experimentally.
Detection of Viral Nucleic Acids
Detection of viral nucleic acids provides a highly sensitive and specific approach to the diagnosis of current HEV infection. Reverse transcription PCR (RT–PCR), and loop-mediated isothermal amplification are the two different techniques used at present.
New Assay Formats
An immunofluorescence assay for detection of viral antigens in liver tissue was developed using an immune-fluorescent probe prepared from serum from a patient recovering from hepatitis E. An enzyme-linked immunosorbent spot (ELISPOT) assay for the detection of cell-mediated immune responses to HEV has been developed. The detection of specific viral proteins is used as a marker of infection with several viral and nonviral pathogens, such as HBV, HCV, and malarial parasites. A similar approach, using an indirect sandwich enzyme immunoassay (EIA), has been tried for HEV. This assay uses plates coated with a mixture of three monoclonal antibodies against the HEV capsid protein. The captured HEV antigen is then detected by sequential addition of another anti-HEV-ORF2 antibody, a biotin-labeled secondary antibody, and an enzyme-streptavidin conjugate.
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