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Hepatitis B, Acute


Sonal Kumar

, MD, MPH, Weill Cornell Medical College

Reviewed/Revised Aug 2022 | Modified Sep 2022
Topic Resources

Hepatitis B is caused by a DNA virus that is often parenterally transmitted. It causes typical symptoms of viral hepatitis, including anorexia, malaise, and jaundice. Fulminant hepatitis and death may occur. Chronic infection can lead to cirrhosis and/or hepatocellular carcinoma. Diagnosis is by serologic testing. Treatment is supportive. Vaccination is protective and postexposure use of hepatitis B immune globulin may prevent or attenuate clinical disease.

Hepatitis B virus (HBV) is the most thoroughly characterized and complex hepatitis virus. The infective particle consists of a viral core plus an outer surface coat. The core contains circular double-stranded DNA and DNA polymerase, and it replicates within the nuclei of infected hepatocytes. A surface coat is added in the cytoplasm and, for unknown reasons, is produced in great excess.

HBV is the 2nd most common cause of acute viral hepatitis Overview of Acute Viral Hepatitis Acute viral hepatitis is diffuse liver inflammation caused by specific hepatotropic viruses that have diverse modes of transmission and epidemiologies. A nonspecific viral prodrome is followed... read more after hepatitis A Hepatitis A Hepatitis A is caused by an enterically transmitted RNA virus that, in older children and adults, causes typical symptoms of viral hepatitis, including anorexia, malaise, and jaundice. Young... read more . Prior unrecognized infection is common but is much less widespread than that with hepatitis A virus. In the US, 3322 cases of acute hepatitis B infection were reported in 2018—a decrease from the 25,000 annual cases reported before use of hepatitis B vaccine became widespread. However, because many cases are not recognized or not reported, the Centers for Disease Control and Prevention (CDC) estimates that the actual number of new infections was about 21,600 in 2018 (1 General references Hepatitis B is caused by a DNA virus that is often parenterally transmitted. It causes typical symptoms of viral hepatitis, including anorexia, malaise, and jaundice. Fulminant hepatitis and... read more ).

Occasionally, coinfection with hepatitis D occurs.

Transmission of hepatitis B

HBV is often transmitted parenterally, typically via contaminated blood or blood products. Routine screening of donor blood for hepatitis B surface antigen (HBsAg) has nearly eliminated the previously common posttransfusion transmission, but transmission through needles shared by drug users remains common. Risk of HBV is increased for patients on dialysis and in oncology units, and for hospital personnel in contact with blood.

Infants born to infected mothers have a 70 to 90% risk of acquiring hepatitis B during delivery (see Neonatal Hepatitis B Virus Infection Neonatal Hepatitis B Virus (HBV) Infection Neonatal hepatitis B virus infection is usually acquired during delivery. It is usually asymptomatic but can cause chronic subclinical disease in later childhood or adulthood. Symptomatic infection... read more ) unless they are treated with hepatitis B immune globulin (HBIG) and are vaccinated Prevention Neonatal hepatitis B virus infection is usually acquired during delivery. It is usually asymptomatic but can cause chronic subclinical disease in later childhood or adulthood. Symptomatic infection... read more immediately after delivery. Earlier transplacental transmission can occur but is rare. The risk of vertical transmission of HBV is also mitigated by treating actively infected pregnant women with high viral loads in their third trimester with tenofovir.

The virus may be spread through mucosal contact with other body fluids (eg, between sex partners, both heterosexual and homosexual; in closed institutions, such as mental health institutions and prisons), but infectivity is far lower than that of hepatitis A virus, and the means of transmission is often unknown.

The role of insect bites in transmission is unclear. Many cases of acute hepatitis B occur sporadically without a known source.

Chronic HBV carriers provide a worldwide reservoir of infection. Prevalence varies widely according to several factors, including geography (eg, < 0.5% in North America and northern Europe, > 10% in some regions of the Far East and Africa).

General references

Symptoms and Signs of Acute Hepatitis B

Hepatitis B infection causes a wide spectrum of liver diseases, from a subclinical carrier state to severe hepatitis or acute liver failure (fulminant hepatitis Fulminant Hepatitis Fulminant hepatitis is a rare syndrome of rapid (usually within days or weeks), massive necrosis of liver parenchyma and a decrease in liver size (acute yellow atrophy); it usually occurs after... read more ), particularly in older people, in whom mortality can reach 10 to 15%.

Five to 10% of all patients with acute HBV infection develop chronic hepatitis B Hepatitis B, Chronic Hepatitis B is a common cause of chronic hepatitis. Patients may be asymptomatic or have nonspecific manifestations such as fatigue and malaise. Diagnosis is by serologic testing. Without treatment... read more . The younger the age that acute hepatitis B occurs, the higher the risk of developing chronic hepatitis B. For immunocompetent people, risk of developing chronic hepatitis B infection is as follows:

  • For infants: 90%

  • For children aged 1 to 5 years: 25 to 50%

  • For adults: About 5%

Diagnosis of Acute Hepatitis B

  • Serologic testing

If acute viral hepatitis is suspected, the following tests are done to screen for hepatitis viruses A, B, and C:

  • IgM antibody to HAV (IgM anti-HAV)

  • Hepatitis B surface antigen (HBsAg)

  • IgM antibody to hepatitis B core (IgM anti-HBc)

  • Antibody to hepatitis C virus (anti-HCV) and hepatitis C RNA (HCV-RNA) polymerase chain reaction

If any of the hepatitis B tests are positive, further serologic testing may be necessary to differentiate acute from past or chronic infection (see table Hepatitis B Serology Hepatitis B Serology* Hepatitis B Serology* ). If serology suggests hepatitis B, testing for hepatitis B e antigen (HBeAg) and antibody to hepatitis B e antigen (anti-HBe) is usually done to help determine the prognosis and to guide antiviral therapy. If serologically confirmed HBV infection is severe, antibody to hepatitis D virus (anti-HDV) is measured.

Hepatitis B has at least 3 distinct antigen-antibody systems that can be tested:

  • HBsAg

  • Hepatitis B core antibody (HBcAb)

  • HBeAg

HBsAg characteristically appears during the incubation period, usually 1 to 6 weeks before clinical or biochemical illness develops, and implies infectivity of the blood. It disappears during convalescence. However, HBsAg is occasionally transient. The corresponding protective antibody (anti-HBs) appears weeks or months later, after clinical recovery, and usually persists for life; thus, its detection indicates past HBV infection and relative immunity. In 5 to 10% of patients, HBsAg persists and antibodies do not develop; these patients develop chronic hepatitis B.

HBcAb reflects antibody to the viral core. Hepatitis B core antigen (HBcAg) is detectable in infected liver cells but not in serum except by special techniques. Antibody to HBcAg (anti-HBc, or HBcAb) usually appears at the onset of clinical illness; thereafter, titers gradually diminish, usually over years or life. Its presence with anti-HBs indicates recovery from previous HBV infection. Anti-HBc is also present in chronic HBsAg carriers, who do not mount an anti-HBs response. In acute infection, anti-HBc is mainly of the IgM class, whereas in chronic infection, IgG anti-HBc predominates. IgM anti-HBc is a sensitive marker of acute HBV infection and occasionally is the only marker of recent infection, reflecting a window between disappearance of HBsAg and appearance of anti-HBs.

HBeAg is a protein derived from the viral core (not to be confused with hepatitis E virus). Present only in HBsAg-positive serum, HBeAg tends to suggest more active viral replication and greater infectivity. In contrast, presence of the corresponding antibody (anti-HBe) suggests lower infectivity. Thus, e antigen markers are more helpful in prognosis than in diagnosis. Chronic liver disease develops more often among patients with HBeAg and less often among patients with anti-HBe.

HBV-DNA can be detected in the serum of patients with active HBV infection.


Other tests

Liver tests are needed if they were not previously done; they include serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase.

Other tests should be done to evaluate liver function; they include serum albumin, bilirubin, and prothrombin time/international normalized ratio (PT/INR).

Treatment of Acute Hepatitis B

  • Supportive care

  • For fulminant hepatitis B, antiviral drugs and liver transplantation

No treatments attenuate acute viral hepatitis, including hepatitis B. Alcohol should be avoided because it can increase liver damage. Restrictions on diet or activity, including commonly prescribed bed rest, have no scientific basis.

Viral hepatitis should be reported to the local or state health department.

Prevention of Acute Hepatitis B

Patients should be advised to avoid high-risk behavior (eg, sharing needles to inject drugs, having multiple sex partners).

Blood and other body fluids (eg, saliva, semen) are considered infectious. Spills should be cleaned up using dilute bleach. Barrier protection is recommended, but isolation of patients is of no value.

Posttransfusion infection is minimized by avoiding unnecessary transfusions and screening all donors for hepatitis B and C. Screening has decreased the incidence of posttransfusion hepatitis B and hepatitis C, which are now extremely rare in the US.


Preexposure immunization has long been recommended for people at high risk. However, selective vaccination of high-risk groups in the US and other nonendemic areas has not substantially decreased the incidence of HBV infection; thus, vaccination is now recommended for all US residents 18 years old beginning at birth (see Centers for Disease Control and Prevention [CDC]: Child and Adolescent Immunization Schedule by Age). Universal worldwide vaccination is desirable but is too expensive to be feasible.

Adults at high risk of HBV infection should be screened and vaccinated if they are not already immune or infected (see also the CDC's Adult Immunization Schedule). These high-risk groups include

  • Men who have sex with men

  • People with a sexually transmitted infection

  • People who have had > 1 sex partner during the previous 6 months

  • Health care and public safety workers potentially exposed to blood or other infectious body fluids

  • People who currently or have recently injected illicit drugs

  • People who have diabetes and are < 60 years old (or 60 years if their risk of acquiring HBV is considered increased)

  • People with end-stage renal disease who receive dialysis, HIV infection, or chronic liver disease, or hepatitis C

  • Household contacts and sex partners of people who are HBsAg-positive

  • Clients and staff members of institutions and nonresidential day care facilities for people with developmental disabilities

  • People in correctional facilities or facilities providing services to injection-drug users

  • International travelers to regions with high or intermediate HBV endemicity

Postexposure prophylaxis

Hepatitis B postexposure immunoprophylaxis combines vaccination with hepatitis B immune globulin (HBIG), a product with high titers of anti-HBs. Efficacy of postexposure HBIG is about 75%.

For infants born to HBsAg-positive mothers, an initial dose of vaccine plus 0.5 mL of HBIG is given IM in the thigh immediately after birth.

For anyone having sexual contact with an HBsAg-positive person or percutaneous or mucous membrane exposure to HBsAg-positive blood, 0.06 mL/kg of HBIG is given IM within days, along with vaccine.

Any previously vaccinated patient sustaining a percutaneous HBsAg-positive exposure is tested for anti-HBs; if titers are < 10 mIU/mL, a booster dose of vaccine is given.

Key Points

  • Hepatitis B is often transmitted by parenteral contact with contaminated blood but can result from mucosal contact with other body fluids.

  • Infants born to mothers with hepatitis B have a 70 to 90% risk of acquiring infection during delivery unless the infants are treated with hepatitis B immune globulin (HBIG) and are vaccinated after delivery; risk is also decreased by treating actively infected third trimester pregnant mothers who have high viral loads with tenofovir.

  • Chronic infection develops in 5 to 10% of patients with acute hepatitis B and often leads to cirrhosis and/or hepatocellular carcinoma.

  • Diagnose by testing for hepatitis B surface antigen and other serologic markers.

  • Treat supportively.

  • Routine vaccination beginning at birth is recommended for all.

  • Postexposure prophylaxis consists of HBIG and vaccine; HBIG probably does not prevent infection but may prevent or attenuate clinical hepatitis.

More Information

The following is an English-language resource that may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

  • Centers for Disease Control and Prevention (CDC): Hepatitis B questions and answers for health professionals: This resource provides an overview of hepatitis B (including statistics, transmission, risk factors, screening, symptoms, diagnosis, and treatment), as well as information about the hepatitis B vaccine and hepatitis B and international travel. Accessed June 8, 2022.

Drugs Mentioned In This Article

Drug Name Select Trade
BayHep B, Hepagam B, Hep-B-Gammagee, HyperHEP B, HyperHEP S/D, Nabi-HB
Engerix-B, Engerix-B Pediatric, H-B-Vax, HEPLISAV-B, PreHevbrio, RDNA H-B Vax II, Recombivax HB, Recombivax HB Pediatric/Adolescent
Albuked , Albumarc, Albuminar, Albuminex, AlbuRx , Albutein, Buminate, Flexbumin, Kedbumin, Macrotec, Plasbumin, Plasbumin-20
NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
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