Hepatitis A virus - Lab Diagnosis, Treatment, Prophylaxis
Laboratory diagnosis of Hepatitis A virus
The laboratory diagnosis of the Hepatitis A virus is as follows:
Specimen
serum for antibody detection test
liver, bile, stool, and blood for HAV Ag
Genome
Direct antigen detection
The virus is present in stool for 2 weeks prior to the onset of jaundice virus is demonstrated in stool during this period by using immunoelectron microscopy.
Isolation of the Hepatitis A virus
Isolation by the culture of feces in the cell line is not routinely done because the facilities for growing the virus are not widely available.
The Hepatitis A virus has been grown in human and simian cell culture
Serodiagnosis
The serodiagnosis of the Hepatitis A virus is done by following tests.
ELISA detects IgM and IgG antibodies in serum.
IgM antibody is the first Ab to appear at the onset of symptoms and continues to persist at a high level for 1-2 months. It disappears by 4-6 months but occasionally persists longer. Hence. IgM antibodies can be used for diagnosis.
A four-fold rise in IgG antibody titer is diagnostic of infection
Radioimmunoassay
Immune electron microscopy
Molecular diagnosis
DNA probes and polymerase chain reaction (PCR) can be used to demonstrate the HAV genome in the stool, and serum of infected patients.
Other tests
LFT is highly useful for supplementing the diagnosis of HAV infection
ALT and AST levels are nearly 4-100 times more than normal levels
serum bilirubin level is also increased and it increases with the appearance of jaundice
decreased serum albumin level and prolongation of prothrombin time indicate a severe hepatocellular infection
Treatment of Hepatitis A virus
There is no specific treatment for the Hepatitis A virus; treatment is supportive
Normal immunoglobulin has a protective effect when given before or shortly after exposure
If fulminant hepatitis develops, liver transplantation may be needed.
Prophylaxis of Hepatitis A virus
The prophylaxis of Hepatitis A virus includes:
Vaccination
Both inactivated and attenuated vaccines have been developed
Active immunization with vaccines containing formalin-inactivated HAV is available
It is given in two days, an initial dose followed by a booster dose after 6-12 months
Although childhood immunization is not recommended, immunization should be offered to people traveling from industrialized countries to HAV endemic regions, patients with chronic liver disease, homosexual men, etc.
Measures to prevent the few-oral spread of infection
good hygienic measures and food safety
safe drinking water and proper disposal of sanitary waste
determining sources of infection
identifying contacts of case patients for post-exposure prophylaxis by administration of Hepatitis A immunoglobulin within 2 weeks of exposure.