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Epidemiology, prevention and control of viral hepatitis B
1.
2. • Formerly known as “Serum” Hepatitis
• Acute self limiting systemic infection transmitted usually by parenteral
route.
• Incubation Period: 50-180 days (avg 60-90)
• Principal age distribution 15-29 yrs.
• Seasonal Incidence: Through out the year.
• In 5-15% cases, hepatitis fails to resolve and the affected individuals
become persistent carriers of the virus.
3. • Hepatitis B is endemic throughout the world, esp. in tropical and
developing countries.
• Prevalence depends upon a complex mix of
• Behavioral
• Environmental
• Host Factors
4.
5. • Based on different HBsAg carrier rates, countries can be divided into 3
categories –
High Endemicity: >=8%
Intermediate Endemicity:>=2-8%
Low Endemicity:<2%
• Countries of the region can be divided on three epidemiological patterns-
Type 1:
In Nepal & Sri Lanka
Characterized by low HBsAg carrier rate of 0.9-1%
Type 2:
In Bhutan, India, Indonesia and Maldives.
Carrier rate is high: 5-7%
Type 3:
In Bangladesh, DPR Korea, Myanmar and Thailand
Carrier rate is very high: 9%-12%
6. Agent Factors-
a) Agent: Discovered by Blumberg in 1963
• Three morphological forms found in patient’s serum
Small spherical particles of avg diameter 22nm- constitute the
bulk.
Tubules of varying length and diameter
Dane particles- considered infectious.
b) Reservoir of infection: Man is the only reservoir and infection spreads either
from carrier or cases.
c) Infective material: Contaminated blood is the main source of infection.
d) Virus is readily destroyed by Sodium hypochlorite.
7. Host Factors:
a) Age- Acute Hepatitis B occurs in approx. 1% of perinatal, 10% early
childhood(1-5 yrs of age) and 30% of late (>5 yrs age) HBV infections.
• Chronic HBV infection is inversely related to age. Occurs in approx.
80-90% of Perinatal infections. 30% early childhood infections and
5% infections after 6 yrs of age.
c) High Risk Groups-
• Annual incidence in surgeons is 50 times greater than general
population.
• Other high risk groups are recipients of blood transfusion, health
care and lab personnel, homosexuals and so on.
d) Hepatitis B and HIV infection- Presence of HIV markedly increases
the risk of developing HBV associated liver cirrhosis and HCC.
e) Humoral and Cellular responses
8.
9. a) Parenteral route: Most common.
b) Perinatal transmission: Infection of baby usually anicteric
and recognized by appearance of HBsAg btw 60-120 days
after birth.
c) Sexual transmission: Particularly in male homosexuals
d) Other Routes: Horizontal transmission from child to child
responsible for majority of HBV infections and carriers in
parts of world other than Asia.
10.
11.
12. No specific treatment therefore prevention has been the major aim in
management using following measures-
Hepatitis B vaccine
Hepatitis B immunoglobulin (HBIG)
Passive-Active immunization
Other measures
13. •Recombinant Hepatitis B vaccine was introduced in 1986.
•Active substance in HBsAg
•In India 4 dose schedule is followed under NIS for infants.
a) At Birth within 24 hrs - first dose.
b) 3 additional doses at 6 ,10 and 14 weeks with DPT.
c) Minimum recommended interval btw doses is 4 weeks.
• In countries where high proportion of HBV infection is
acquired perinatally, vaccine should be given within 24
hrs after birth.
14. • Immunization in Adults:
a) Considered for groups at high risk of HBV infections like person
with high risk sexual behavior ,partners, injecting drug users, etc.
b) Adults >= 20 yrs should receive 1ml of adult formulation in 3 doses.
c) First two doses separated by no less than 4 weeks.
d) Third dose 4-6 months after second.
HepB vaccine is contraindicated for individuals with H/O allergic reactions to any
of its components.
Vaccine should be stored at 2-8 °C
Freezing must be avoided.
Second vaccine series is started in those who fail to respond to primary
vaccination series.
Given on the usual 0,1 and 6 month schedule.
Revaccinated personnel should be tested 1-2 months later.
15. For immediate protection.
For those acutely exposed to HBsAg positive blood.
a) Surgeons, nurses or lab workers
b) Newborn infants of carrier mothers.
c) Sexual contacts of acute HepB patients.
d) After liver transplantation.
HBIG should be given as soon as possible (ideally within 6 hrs and
preferably not later than 48 hrs of accidental inoculation)
Recommended Dose- 0.05-0.07 ml/Kg body wt.
Two doses given 30 days apart.
Provide short term passive protection for 3 months.
16. Simultaneous administration of HBIG and HepB vaccine is more
efficacious than HBIG alone.
Ideal for prophylaxis as well as prevention of carrier state in new
born babies of carrier mothers.
HBIG given as soon as possible within 24 hrs.
HepB vaccine should be given i/m within 7 days of exposure.
Second and third doses should be given one and six months,
resp, after first dose.
17. Blood donors positive for HBsAg should be rejected.
Health personnel should be alerted to the importance of
adequate sterilization.
Carrier should be told not to share razors or tooth
brushes and use barrier method of contraception.
18. Park’s Textbook of Preventive and social medicine.,23rd
edition
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