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HEPATITIS A VIRUS (HAV)

HEPATITIS A VIRUS (HAV)

HAV was classified as an enterovirus type 72. It is now placed in anew genus in the picornavirus family called “Hepatovirus”. It is an RNA, icosahedral virus 27-30nm in diameter. Only one serotype is known. The virus is relatively heat resistant, it with stands 60c⁰ for 1 hour It is destroyed by boiling for 5 minutes. It is pathogenic to primates e.g. man and chimpanzees. It grows on primary cell lines of primate liver and human diploid cells

• Epidemiology: It is transmitted by the faecal- oral route. Incubation period is 2-6 week i.e. shorter than that of HBV. The manifestations are the same in all hepatitis viruses i.e. jaundice, fever, abdominal pain and anorexia HAV infection is usually milder than HBV many cases are non–icteric or asymptomatic. Recovery occurs without complications; no carrier, no chronic hepatitis or HCC and is followed by long lasting immunity.

The virus is found in the stools 2 weeks before and 2 weeks after the jaundice appears.

It affects mainly children and youg adults (5-15 years)

It may occur in sporadic or epidemic forms in summer comps or schools. It occurs mainly in the autumn

• laboratory diagnosis

1. Increased level of liver enzymes
2. Detection of HAV IGM or arising titre of IgG by RIA or ELISA is diagnostic of recast infection
3. PCR is applicable, but is not routinely used.
4. Detection of the virus in stools by immunoelectron microscopy is not routinely used.

• Prophylaxis:

Inactivated vaccine “Havrix” is licensed for use since 1995. It is recommended for children over over 2 years and is given intra muscularly in the deltoid region in 3 doses at 0.1 and 6 month the vaccine may be given to travelers, Armed forces and medical staff. Gamma globulin if given early after exposure renders the infection milder or sub clinical.

HEPATITIS A VIRUS (HAV)

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