Hepatitis A: State of the Art Knowledge

With tremendous advancements related to hepatitis B treatment in the last few years, the other types of hepatitis viruses are often overlooked. One, hepatitis A virus (HAV), causes a considerable amount of morbidity globally, and it is also vaccine-preventable. The rates of HIV infection are low and decreasing in most industrialized nations, but HAV infection does occur.

The Journal of Hepatology has published an article that describes the current knowledge of HAV in detail.

HAV infection replicates in hepatocytes and can causes necro-inflammatory hepatic damage. It is an acute infection, and resolves spontaneously in approximately 99% of individuals who are affected. However, some patients—up to 20%—may experience clinical relapse. Its symptoms (fatigue, nausea and vomiting, abdominal pain, anorexia, fever, loss of appetite) can be debilitating, especially in patients who have chronic nonviral liver disease. When liver injury occurs, it is caused by innate and adaptive immune responses to viral infection.

HAV's clinical outcomes vary by the age of the patient. Children generally present with no symptoms whatsoever, but the clinical presentation can be more severe as patients age.

Researchers around the world track HAV's global incidents and use the collected data to predict the potential for outbreaks and shifts. Their main concern is vulnerable populations, particularly the elderly.

Patients who have been exposed to HAV have 2 options. First, they can receive pooled human immunoglobulin with a goal of passively transferring anti-HAV antibodies. This approach is costly and provides only short-term protection, and for these reasons has fallen into disfavor.

Alternatively, exposed individuals may receive inactivated HAV vaccine within 2 weeks as a form of post-exposure immunization. The researchers indicate that the latter intervention's effectiveness is surprising since the circulating virus is cloaked in membranes and resistant to antibody-mediated neutralization.

However, researchers currently have no serologic assay that can differentiate between natural and vaccine-induced immunity against HIV, which affects their ability to track the virus's epidemiology.

Many countries have introduced universal immunization programs and have seen significant decreases in the incidence of HAV infection.

This is a comprehensive review that can help pharmacists understand HAV infection and its related issues, and emphasize the value in vaccination.

Reference

Lemon SM, Ott JJ, Van Damme P, et al. Type A viral hepatitis: A summary and update on the molecular virology, epidemiology, pathogenesis and prevention. J Hepatol. 2017 Sep 5. pii: S0168-8278(17)32278-X. doi: 10.1016/j.jhep.2017.08.034. [Epub ahead of print]