Transcript Epidemiology and Prevention of Viral Hepatitis A to E:

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