Hepatitis A virus (HAV) is a small sized (27nm), RNA virus of the family picornaviridae. It can be inactivated by boiling for one minute or by exposure to UV-light, chlorine and formaldehyde. Hepatitis A is prevalent in many parts of world where there is a poor sanitization facility and overcrowding.
Transmission Of Hepatitis A Virus
- HAV is transmitted by faeco-oral route.
- Infection is acquired by consumption of contaminated food or water. Consumption of seafood has also been implicated.
- Person to person spread is common mode of transmission.
- Viral excretion in stools of infected person begins few days to two weeks prior to onset of symptoms and decline after jaundice appears.
- Incubation period is between 15 to 50 days.
- There is no animal reservoir of this infection.
Symptoms Of Hepatitis A
- Clinical presentation can range from asymptomatic infection to fulminant hepatic failure.
- Commonly, acute hepatitis illness occurs with an abrupt onset.
- Initial symptoms are fever, malaise, fatigue, anorexia and vomiting.
- Some patients have an aversion to food and smoking.
- These are soon followed by dark colored urine and appearance of jaundice.
- Some patients may notice clay colored stools and itching.
- Fever is usually mild to moderate, not associated with chills and improves as jaundice appears.
- Jaundice remains for a few weeks and then gradually improves.
- Clinical examination usually shows icterus (yellowish discoloration of the sclera) and slightly enlarged, mildly tender liver.
- The illness lasts for less than eight weeks.
- HAV causes self limiting illness with usually no sequence.
- It does not lead to chronic carrier state, chronic hepatitis or cirrhosis of liver.
Hepatitis A Diagnosis
- Diagnosis of HAV infection is based on detection of antibodies against HAV in serum.
- IgM HAV are 1st to appear and can be detected in early course of illness. Therefore presence of IgM anti-HAV in serum suggests a recent HAV infection.
- Presence of IgM anti-HAV on the other hand suggests an infection sometimes in the past and that the individual is immune to HAV infection.
- Diagnosis of acute infection can also be made by detection of viral particles in stool specimens.
Hepatitis A Treatment And Prevention
No specific treatment is available for HAV infection, since the illness is mild and self-limiting. Bed rest and dietary precautions like fat restriction, liberal use of sugars and carbohydrate are prescribed.
Transmission of HAV can be prevented by ensuring clean and safe water supply and by following hygienic food preparation and consumption practices.
For HAV infection, specific immuno-prophylaxis, both active and passive is possible.
Hepatitis A Vaccination
- Intra-muscular administration of immune serum globulin before or soon after exposure to HAV infection leads to a milder infection. Protective effect of this dose lasts for 2 to 3 months.
- Use of immune serum globulin is recommended in persons who are not previously exposed and are at risk of getting this infection like travelers.
- Passive immunization is recommended for household and day care centre contact of patients with HAV.