Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Hepatitis B Virus Hepatitis B - Clinical Features • Incubation period: Average 60-90 days Range 45-180 days • Clinical illness (jaundice): <5 yrs, <10% 5 yrs, 30%-50% • Acute case-fatality rate: • Chronic infection: 0.5%-1% <5 yrs, 30%-90% 5 yrs, 2%-10% • Premature mortality from chronic liver disease: 15%-25% Acute Hepatitis B Virus Infection with Recovery Typical Serologic Course Symptoms anti-HBe HBeAg Total anti-HBc Titer 0 4 anti-HBs IgM anti-HBc HBsAg 8 12 16 20 24 28 32 36 Weeks after Exposure 52 100 Progression to Chronic Hepatitis B Virus Infection Typical Serologic Course Acute (6 months) Chronic (Years) HBeAg anti-HBe HBsAg Total anti-HBc Titer IgM anti-HBc 0 4 8 12 16 20 24 28 32 36 Weeks after Exposure 52 Years Rate (per 100,000) Rate of Reported Hepatitis B by Age Group 25 United States, 1990 20 15 10 5 0 0-14 15-19 20-29 Age Group (Years) Source: CDC Viral Hepatitis Surveillance Program 30-39 40+ Age at Aquisition of Acute and Chronic HBV Infection United States, 1989 Estimates Adult (83%) (4% ) Perinatal (24%) (4%) Children (12%) (1-10 yrs) (8%) Adolescent (6%) Acute HBV Infections Adult (59%) Chronic HBV Infections 100 80 80 60 60 Chronic Infection 40 40 20 20 Symptomatic Infection 0 Birth 1-6 months 7-12 months Age at Infection 1-4 years 0 Older Children and Adults Symptomatic Infection (%) Chronic Infection (%) 100 Outcome of Hepatitis B Virus Infection by Age at Infection Global Patterns of Chronic HBV Infection • High (8%): 45% of global population – lifetime risk of infection >60% – early childhood infections common • Intermediate (2%-7%): 43% of global population – lifetime risk of infection 20%-60% – infections occur in all age groups • Low (<2%): 12% of global population – lifetime risk of infection <20% – most infections occur in adult risk groups Geographic Distribution of Chronic HBV Infection HBsAg Prevalence 8% - High 2-7% - Intermediate <2% - Low Concentration of Hepatitis B Virus in Various Body Fluids High Moderate blood serum wound exudates semen vaginal fluid saliva Low/Not Detectable urine feces sweat tears breastmilk Hepatitis B Virus Modes of Transmission • Sexual • Parenteral • Perinatal Risk Factors for Acute Hepatitis B United States, 1992-1993 Heterosexual* (41%) Injecting Drug Use (15%) Homosexual Activity (9%) Household Contact (2%) Health Care Employment (1%) Unknown (31%) Other (1%) * Includes sexual contact with acute cases, carriers, and multiple partners. Source: CDC Sentinel Counties Study of Viral Hepatitis Elimination of Hepatitis B Virus Transmission United States Objectives • • • • Prevent chronic HBV Infection Prevent chronic liver disease Prevent primary hepatocellular carcinoma Prevent acute symptomatic HBV infection Elimination of Hepatitis B Virus Transmission United States Strategy • • • • Prevent perinatal HBV transmission Routine vaccination of all infants Vaccination of children in high-risk groups Vaccination of adolescents – all unvaccinated children at 11-12 years of age – “high-risk” adolescents at all ages • Vaccination of adults in high-risk groups Cases per 100,000 Population Estimated Incidence of Acute Hepatitis B United States, 1978-1995 80 Vaccine licensed 70 HBsAg screening Infant of pregnant immunization women recommended recommended 60 OSHA Rule enacted 50 Adolescent immunization recommended 40 30 20 Decline among homosexual men & HCWs 10 0 Decline among injecting drug users * 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 * Provisional date Year