LAUSR

One more “World Hepatitis Day” has just passed and amidst all the global attention that hepatitis B and C get, complicated disease course due to hepatitis A becomes an emerging battle in countries undergoing epidemiological transition from high to intermediate endemicity. Globally, hepatitis A accounts for 126 million cases of acute hepatitis and 35,245 deaths every year [1]. It is well known that hepatitis A has age-dependent clinical manifestations, being asymptomatic in early childhood and causing icteric illness and complications in adolescence and adulthood. In regions with high endemicity, hepatitis A causes asymptomatic infection in almost everyone during childhood thus conferring life-long immunity, whereas the low endemicity areas have low circulation of hepatitis A with a large vulnerable population not exposed to the virus due to better sanitation and hygiene. Therefore, hepatitis A is not a major public health problem in in high endemicity areas, except for local outbreaks. Holding a unique place in the epidemiology of hepatitis A are the intermediate endemicity areas, which have high circulation of hepatitis A but a fair number of the population have climbed up the socio-economic ladder rendering them susceptible to hepatitis A with a complicated course [2]. The World Health Organization suggests the following classification for endemicity – High: ≥90% seroprevalence by 10 years of age; intermediate: <90% by 10 years and ≥50% by 15 years; low: ≥50% by 30 years and <50% by 15 years; and very low: <50% by 30 years [1]. As countries have a transition from high endemicity to intermediate endemicity, the number of clinically significant hepatitis A would paradoxically go up. Though there is paucity of large epidemiological studies, India is possibly in transit from high to intermediate endemicity as suggested by a study of 928 children that showed that the seroprevalence of hepatitis A is 50% in children aged 6 to 10 years [3]. In another laboratory surveillance data study, 25% cases of Hepatitis A disease occurred after 19 years of age [4]. In contrast, earlier studies showed seroprevalence of anti HAV IgG to be 84% by 6 years and 96% by 12 years of age [5]. Hence, this time of epidemiological shift in India is the most apt to examine hepatitis A related clinical illness with a fresh perspective.