Hepatitis B Flashcards
References: Evidence-Based MFM, Ch 30; Creasy & Resnik
What is the vertical transmission rate of HBV in women with HBeAg+?
95%
What is the vertical transmission rate of HBV in women who are HBsAg+ but HBeAg-?
25%
What is the vertical transmission rate of acute HBV in the third trimester?
90%
Without intervention, what percent of newborns infected with HBV develop chronic hepatitis? How many develop complications?
90%, with 25% of chronic HBV carriers eventually dying of complications (cirrhosis, hepatocellular cancer)
What vaccines do newborns born to women with HBV receive? Efficacy?
HBIg, HB vaccine, within 12 hrs of birth, prevents 90% of neonatal HBV infection
Is breastfeeding contraindicated in HBV+ mothers?
Breast-feeding is not contraindicated, as long as the mother is HBeAg- and HIV-, and the newborn receives appropriate immunoprophylaxis.
Labs for serologic diagnosis of acute HBV
HBsAg+, HBcAb+, HBcIgM+, HBsAb–
Labs for serologic diagnosis of chronic HBV
HBsAg+ >6 months, HBsAb–
Differential diagnosis of hepatitis
Hepatic A, B, or C virus Cytomegalovirus (CMV) Epstein–Barr Varicella (VZV) Coxsackie B Herpes (HSV) Rubella Autoimmune
Diagnosis of newborn HBV
Detection of persistent (e.g., >9 months of age) HBsAg. Only HbsAb is attributable to newborn vaccination: HBcAb arises only as the result of actual HBV infection.
Symptoms of acute HBV
Only 30% to 50% of patients acutely infected have symptoms such as loss of appetite, malaise, nausea, and vomiting. About 10% have jaundice. The onset is usually insidious.
Natural history of HBV infection
One-third of the world’s population (two billion people) have been infected with HBV: 90% have complete resolution, while about 10% overall develop chronic HBV infection; but this incidence is 90% in children 5 years old. About 25% of HBV chronic infection patients die of liver disease (4000/yr in the United States, >1 million/yr world-wide—0.5% mortality)
HBV vaccine efficacy
The vaccine is about 95% effective against HBV.
HBV incubation period
60-90 days
HBV antigens
“s” surface—infected. If present >6 months = chronic HBV infection
“c”—core
“e”—infectious
HBV antibodies
“s”—immune
“c”—covers “window” period, and usually precedes HBsAb conversion
Risk of chronic HBV infection
About 5% of HBV infections become chronic. This can lead to cirrhosis, hepatocellular carcinoma, and death.
Interpret this HBV panel: HbsAg - Anti-HBc - Anti-HBs - Vertical transmission rate?
Susceptible
0%
Interpret this HBV panel: HbsAg - Anti-HBc + Anti-HBs + Vertical transmission rate?
Immune bc of natural infxn
0%
Interpret this HBV panel: HbsAg - Anti-HBc - Anti-HBs + Vertical transmission rate?
Immune bc of HB vaccine
0%
Interpret this HBV panel: HbsAg + Anti-HBc + Anti-HBc IgM + Anti-HBs - Vertical transmission rate?
Acutely infected First trimester: 10% Third trimester: 90% HBeAg -: 10–20% HBeAg +: 90%
Interpret this HBV panel: HbsAg + Anti-HBc + Anti-HBc IgM - Anti-HBs - Vertical transmission rate?
Chronically infected
HBeAg -: 2–10%
HBeAg +: 90%
Interpret this HBV panel:
HbsAg -
Anti-HBc +
Anti-HBs -
Four interpretations possible:
- May be recovering from acute HBV infection
- May be distantly immune and test is not sensitive enough to detect very low level of anti-HBs in serum
- May be susceptible with false-positive anti-HBc
- May be an undetectable level of HBsAg present in the serum and the person is actually a carrier
Blood transfusion HBV transmission risk
1/137,000 transfused units of screened blood
HBV risk factors
Intravenous drug abuse Sexually transmitted diseases Multiple sex partners House contacts Metal institution/prison Acupuncture are other risk factors HBV-infected patients are at higher risk of HIV and HCV infections.
Complications of HBV
- Ninety percent of patients resolve the infection (clear the s and e Ag) and develop HBsAb
- 10% develop chronic HB (maintain HBsAg). Of these, most are asymptomatic with normal liver function tests (LFTs), and no HBV detectable by PCR.
- The other 15% to 30% of chronic HB has persistent viral replication: these patients can develop cirrhosis and hepatocellular cancer. Mortality is 0.5% to 1%. This is more common in pts coinfected with HCV or HIV.
Lamivudine for HBV - efficacy, dosing
-FDA category B
- >95% efficacy to achieve <150,000 HBV DNA, 167% HbeAg negativity
-Can reverse cirrhosis of the liver.
Given usually as 100 mg from 28 weeks to one month after birth in HBV carrier mothers, has been associated with a significant decrease in the HBV mother-to- child transmission
How to treat HBV exposure in pregnancy
Check serologies, LFTs. If HBsAg- and sAb-, give HBIg and begin the HB vaccine series (preferably within 24 hours of exposure): this combination will prevent 75% of transmission. Must give HBIg within 14 days of sexual contact. Repeat HBIg within one month if blood or mucous membrane exposure.
What is HDV?
Incomplete RNA virus, which can super- infect 20% to 25% of chronic HBV-infected patients. HDV infection worsens chronic HBV infection, so that 25% may die from disease. If HBV is prevented, HDV infection is prevented too. HDV has no effect on pregnancy or fetus/ neonate.
Presence of HBeAg indicates:
Active viral replication and a high level of infectivity.
When should you start lamivudine treatment for HBV in pregnancy, if the pt has had a previous perinatal transmission?
28 weeks
HBV DNA >/= 200,000 IU/mL or >10^6 copies/mL
When should you start lamivudine treatment for HBV in pregnancy, if the pt has NOT had a previous perinatal transmission?
28 weeks
HBV DNA >/= 2,000,000 IU/mL or >10^7 copies/mL
In clinical trials, effect of lamivudine prophylaxis on perinatal HBV transmission with lamivudine prophylaxis decreases by?
The overall effect favored lamivudine prophylaxis when these studies were combined (RR 0.31, 95% CI 0.15-0.63).
