Insights of hepatitis A virus disease burden in Indian subcontinent: why urbanized localities are vulnerable to disease outbreaks?

Hepatitis A virus (HAV) is a spherical, non-enveloped, linear-positive single-stranded RNA virus that belongs to the Picornaviridae family. The virus attacks the liver, which leads to inflammation and the onset of jaundice. It represents a disease of the pediatric population and, in most cases, it causes an acute self-limited illness, but rarely a fulminant condition. HAV spreads from person to person through the fecal-oral route and ingestion of contaminated food or drink. It is highly endemic in large geographical areas of the world, including the Indian subcontinent, where most of the population is exposed to the virus in childhood. Most of the viral infections at this age cause asymptomatic disease that provides lifelong protection against HAV. However, our recent study showed an increased incidence of HAV infection in the adult population. This signifies a change in the pattern of age-specific seroprevalence of antibodies for hepatitis A and a huge number of non-immune susceptible individuals. Molecular epidemiological studies define various aspects of viral infection and transmission. Sequence characterization based on the VP1/P2A junction region confirmed IIIA and IA as the predominant genotypes circulating in the Indian subcontinent. The duration of the viremia is dependent on the host, and viral genotypes have no role in the severity of the disease. A mutational study confirmed the lack of genetic variations among Indian strains. Due to the high endemicity of this disease in the Indian subcontinent, vaccination is not recommended. However, individuals who are susceptible and seronegative for HAV-IgG should be targeted for vaccination. It will be a rational and cost-effective approach.