Hepatitis A Virus

Sample for Hepatitis A Virus

1. Venous blood is needed to prepare the serum.
2. Random sampling can be used.
3. The serum can be stored at 4 °C for 5 days.
4. Feces can be taken for immuno-electron microscopy.

Purpose of the test (Indications) for Hepatitis A Virus

• To diagnose viral hepatitis A (HAV) infection.

Definition of Hepatitis A Virus (HAV)

1. Hepatitis A viral infection is also called Infectious hepatitis or short incubation hepatitis.
2. Hepatitis A is a non-enveloped virus belonging to the hepatotropic virus family and is 27 nm in diameter.
3. HAV belongs to the Picornaviridae family.
   1. It is a picornavirus.
   2. Genus is a hapatovirus.
4. There is no cross-reactivity with HBV or other hepatotropic viruses.

Structure of the Hepatitis A Virus:

1. It consists of a linear single-stranded RNA virus (ssRNA) genome with 7.5 kb.
2. It measures 27 to 32 nm spherical particles with cubic symmetry.
3. VPg is a Viral protein genome-linked. It is a protein attached to the positive strand of viral RNA.
   1. VPg acts as a primer during RNA synthesis.
4. HAV is a self-limiting acute liver disease.

Hepatitis A virus (HAV) structure

The incubation period of Hepatitis A Virus infection:

1. The incubation period is short, 3 to 4 weeks (range is 2 to 6 weeks).
2. It is highly infectious during active infection and is excreted in the stool.
3. It will spread through contaminated water or food.
4. Urine and alive are less infective than stool.
5. A great number of the virus appears in the stool before the symptoms appear.
6. The number of viruses decreases as the symptoms appear.
7. Complete recovery in 1 to 3 weeks and no carrier state.
8. An occasional patient may have the longer disease for almost one year.

Mode of the spread of HAV infection:

1. Initially, it was found in the stool and liver by E/M.
2. It is a highly contagious viral infection and is most common in children.
   1. Most children recover from the disease and develop lifelong immunity.
   2. It is common in daycares and orphanages.
3. In the active stage, this virus is excreted in the stool.
4. So there is an oro-fecal spread because of the contamination of food and drinks.
5. Sexual transmission between male homosexuals has been reported.
6. Transmission via blood transfusion and I/V drug use is rare.
7. It is most common in the third world, almost 90% to 100%.

The clinical course of Hepatitis A virus (HAV):

1. Mostly asymptomatic.
2. >50% of cases are subclinical, anicteric hepatitis.
3. The most common age group is children.
4. There may be a prodromal period of fever, chills, fatigue, malaise, and headache.
   1. The above symptoms will be followed by nausea and vomiting.
5. There is anorexia.
6. Sometimes there may be abdominal pain which is usually in the upper quadrant.
7. Sometimes there may be gastroenteritis.
8. When jaundice appears, then there is rapid improvement in the clinical symptoms.
   1. Jaundice may last for a few days to 12 weeks.
   2. Usually not infective after the appearance of jaundice.

Outcome Hepatitis A Virus infection:

1. There is mild to severe disease.
2. Mostly recovered from the HAV infection and gets life-long immunity.
3. Very few die of HAV infection with fulminant hepatitis.

Summary of the HAV infection:

High-risk group for Hepatitis A Virus:

1. Child-care centers.
2. The family members who are in close contact with the patient.
3. In the summer camps.
4. People are working in correctional centers.
5. Homosexual peoples.

Immunology of Hepatitis A Virus:

1. The first antibody in acute infection is IgM type (HAV-IgM)
2. IgM appears 3 to 4 weeks after exposure to the virus or before the liver function tests are raised.
   1. IgM returns to normal in roughly 8 weeks or disappears in 3 to 4 months. It is not detectable after 12 months.
3. HAV-IgG appears after 2 weeks when IgM is increasing.
   1. Now IgM slowly comes to normal, and IgG will be present in the blood.
   2. HAV-IgG will be detectable in the blood even after 10 years.

      1. Disease stage	IgM	IgG
         Acute infection	Positive	Negative
         Later on	Positive	Positive
         Immunity	Negative	Positive
         Repeat test 2 weeks later	Not done	Negative

Diagnosis of Hepatitis A Virus:

1. SGPT and SGOT have raised the varying range to hundreds of the normal, which may remain for 1 to 3 weeks.
2. Blood show relative lymphocytosis.
3. HAV-IgM
   1. IgM is macroglobulin, and it indicates acute infection.
   2. It appears in the blood 3 to 4 weeks after exposure to the HAV virus.
   3. Or it appears just before the rise in SGPT.
   4. The peak level reaches one week after the rise begins.
   5. It appears simultaneously when symptoms appear.
   6. It becomes normal in about 2 months after the clinical symptoms become normal,
   7. It is non-detectable for 12 months. In a few cases may be detected in 12 to 14 months.
4. HAV-IgG
   1. It appears after 2 weeks of the beginning of IgM increase.
   2. It is seen in the middle stage of the symptoms.
   3. It peaks in about 1 to 2 months after it begins to rise.
   4. Now its titer will fall and remain low titer for at least 10 years.
   5. The rising titer is needed in only IgG-positive cases.
5. HAV-IgG positive and HAV-IgM negative indicate convalescent or chronic stage.
   1. Anti-HAV- IgG is present throughout life. It is positive in 50% of the USA population, indicating past infection and immune status.
   2. HAV total antibody indicates present or past infection.
   3. HAV total antibody also indicates vaccination.
6. PCR: In the early stage, antibodies are not detectable then. Only PCR for RNA can be found in the stool and blood.
   1. PCR for RNA may be found in the saliva as well.
   2. PCR is rarely needed.
7. The fecal HAV virus is positive 2 weeks before the symptoms appear.
   1. The HAV virus can be detected in the stool as early as 1 to 2 weeks after exposure.
   2. This period ends about 1 to 4 days after the appearance of the symptoms.
   3. At admission in 40% to 64% of the patient, the HAV virus in stool is negative.
8. Summary of HAV virus diagnosis:
   1. For acute infection (current or recent HAV infection) = HAV-IgM.
   2. Past HAV infection/immunity = HAV-antibody total.

Hepatitis A virus (HAV) profile

Preventions of Hepatitis A Virus:

1. The best is to give the vaccine in epidemic areas and to children.
2. Improve:
   1. Safe water supply.
   2. Safe food supply, which is the best hygienically.
   3. Have good sanitation.
   4. Washing of hands before taking the food.

Treatment of Hepatitis A Virus:

• These patients recover without any treatment.
• Mainly there is a need for supportive treatment.

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