Fecal/oral contact with infected persons for a week after jaundice appears; can be transmitted up to a year after clinical disease (Jama 1958;200:365); occasionally parenteral; higher incidence in parents of day care center children, children are often asx (Nejm 1980;302:1222)

In US, incidence has plummeted w childhood immunization now in majority of states (Jama 2005;294:194)

In developing countries, 3/1000/mo incidence for 1st-class hotel users, 20/1000/mo for community living guests; thus is most frequent preventable infection in travelers (Jama 1994;272:885)

Sx:

15-40 d incubation period (Am J Med 5/62)

In children, only 5-15% get sx

Malaise (48% in children/63% in adults), anorexia (41%/42%), abdominal pain (48%/37%), fever and/or chills (41%/32%), jaundice (65%/88%), diarrhea (58%/18%), dark urine (58%/68%), light stools (58%/58%), nausea and vomiting (65%/26%)

Si:Jaundice, though anicteric form also common and more benign

Benign, 15% morbidity and rare (0.3%) mortality (Ann IM 1998;128:111); sx peak 2 wk after onset and take about 4 wk to clear; relapse in 6% at 1-3 mo (Ann IM 1987;106:221)

Fulminant hepatitis, relapsing hepatitis, no chronic active hepatitis (Eric Mast, CDC 11/95)

r/o other pre-, intra-, and post-hepatic causes of jaundice, including hepatocellular disease, obstructive causes

other viral hepatitis non-A, non-B hepatitis like HEPATITIS E virus infection, an enterovirus that causes only acute hepatitis like hep A (Nejm 2004;351:2367) but that sometimes evolves to acute hepatic failure, an enterovirus spread via water sources esp in equatorial areas (Virol 1993;4:273), eg, 80% of Indians have it; and in pregnant women, who have a 25% mortality. Effective recombinant vaccine (rVEV) available as 3-shot series (Nejm 2007;356:1895, 949)

Lab:

Chem:Typical hepatitis enzyme picture w ALT (SGPT) > AST (SGOT) > LDH > alkaline phos levels

Serol:Hepatitis A IgM antibody present when 1st sx present (Ann IM 1982;96:193); later IgM goes negative and IgG appears and stays