Le virus de l'hépatite A : actualités

Hepatitis A virus (HAV) is the leading cause of viral hepatitis worldwide. Infection is usually self limiting, yet, in some cases it may cause fulminant and fatal hepatitis, particularly in patients of more than 50 years old. Improved hygiene standards have led to a reduction in natural immunization allowing potentially massive outbreaks involving adults. This changing epidemiology leads to the modification of public health surveillance systems and vaccine recommendations. The diagnosis of acute infection is based on anti-HAV IgM detection. However, IgM can be detected in the absence of HAV infection, then IgG avidity may help to distinguish between acute infection and immune reactivation. Molecular epidemiology contributes to the identification of linked cases and source of contamination. The observation of the diversity of circulating strains allows to better understand HAV diffusion modes within a community or from a country to another and to adapt the tools for virus detection.