0071643192.pdf

HEPATITISA

RNA picornavirus; endemic worldwide; in the United States, over one-third of

all urban-dwelling adults seropositive for the anti-HAV antibody; common in

children <15 years old; most common cause of conjugated hyperbilirubinemia

in children; rare in persons >40 years old; highest rates seen in American Indians

and Alaska natives

TRANSMISSION

Fecal-oral, contaminated food and water worldwide

SYMPTOMS

■ Presents with flulike illness, malaise, anorexia, weakness, fever, RUQ pain,

jaundice, and pruritus; children are typically asymptomatic

■ Atypical presentations include acute liver failure, cholestasis (prolonged,

deep jaundice), and relapsing disease (2–18 weeks after initial presentation).

DIAGNOSIS

■ History:Inquire about ill contacts, substandard water supply, travel, and

contaminated food (shellfish and green onions).

■ Labs:Anti-HAV IgM (acute infection); anti-HAV IgG (prior exposure, vac-

cination); anti-HAV total measures IgM and IgG (acute infection, prior

exposure, vaccination)

TREATMENT

■ Supportive, rarely progresses into fulminant infection

■ Avoid alcohol and acetaminophent (Tylenol) during acute infection.

HEPATITISB

Some 400 million people worldwide have chronic HBV, including >1 million

in the United States. Transmission can be perinatal (the most common cause

worldwide), sexual, or percutaneous. Age at infection is inversely related to

the risk of chronic infection. Of all patients with chronic HBV, 15–20%

develop cirrhosis and 10–15% develop hepatocellular carcinoma.

TRANSMISSION

Maternal→fetal, body fluids through sexual contact, IVDA.

SYMPTOMS

Similar to acute hepatitis A

DIAGNOSIS(SEETABLE11.12)

■ HBsAg:Surface antigen indicates activeinfection.

■ Anti-HBs:Antibody to HBsAg indicates past viral infection or immunization.

■ Anti-HBc:IgM is an early marker of infection; IgG is the best marker for

prior HBV exposure. IgM may also become detectable in reactivation of

HBV.

■ HBeAg: Proportional to the quantity of intact virus and, therefore,

infectivity; some HBV variants (called precore mutants) cannot make

HBeAg.

ABDOMINAL AND GASTROINTESTINAL

EMERGENCIES