[Hepatitis A virus infection. A review]

Area of Science:

• Hepatology
• Virology
• Immunology

Background:

• Hepatitis A virus (HAV) is a resilient RNA virus transmitted via the fecal-oral route, primarily infecting the liver.
• Liver damage from HAV infection is likely immune-mediated, involving virus-specific immunity interacting with infected hepatocytes.
• While typically self-limiting, HAV infections can be protracted or relapsing, but not chronic.

Purpose of the Study:

• To provide a comprehensive overview of Hepatitis A virus (HAV) epidemiology, pathogenesis, clinical manifestations, diagnosis, and prevention.
• To highlight the differences in HAV prevalence and clinical presentation between developing and industrialized countries.
• To emphasize the role of vaccination in preventing Hepatitis A.

Main Methods:

• Literature review and synthesis of existing data on HAV epidemiology, virology, immunology, and clinical outcomes.
• Analysis of diagnostic methods, including antibody detection for acute infection and immunity assessment.
• Evaluation of preventive strategies, focusing on hygiene and inactivated HAV vaccines.

Main Results:

• HAV is globally distributed, with near-universal childhood infection in areas with poor sanitation, conferring lifelong immunity.
• In industrialized nations, HAV infections are more common in adults and at-risk groups, often presenting with severe icteric hepatitis.
• Anti-HAV-IgM indicates acute infection; anti-HAV-IgG signifies immunity from infection or vaccination.
• Inactivated HAV vaccines are safe, immunogenic, and provide over 20 years of protection.

Conclusions:

• Hepatitis A infection is primarily immune-mediated and usually self-limiting, with no chronic form observed.
• Vaccination and hygiene are crucial for preventing HAV, especially in industrialized countries where adult infections can be severe.
• Long-lasting immunity is achieved through natural infection or vaccination, with inactivated vaccines offering robust protection.