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Viral Hepatitis
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Hepatitis A Virus
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1. Epidemiology
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Has a worldwide distribution (low, intermediate & high endemicity).
Highest levels of endemicity in regions with low standards of
sanitation.
Adults of high endemicity are usually immune / epidemics are
uncommon.
Improving sanitary conditions  many young adults susceptible --
increase frequency of outbreaks.
Children play important role in HAV transmission/ most of cases are
asymptomatic or unrecognized.
In areas in Southeast Asia 90% have serological evidence of past
infection compared to 33% in USA.
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In developed countries epidemics are usually of the propagated
type (evolve slowly, over wide area, and for many months) ;
common source epidemic may evolve rapidly.
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Mode of transmission:
a. Mostly through oral-fecal route.
Common source epidemic at community level is through
contaminated:
- water
- food by food handlers or
- produce before entering the food chain.
b. IV drug users and hemophiliacs outbreaks confirmed the needleborne transmission
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3.
Methods of control:
A. preventive measures
a.
b.
c.
Educate the public on good sanitation
Provide water treatment and distribution system & sewage disposal
system
Vaccine:
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inactivated vaccine
proved to be safe and effective
Not for children under 1 year of age
2 doses required
Protection appear in 14-30 days after first dose; 2nd dose is given for long
time protection.
In high endemic areas it may be cost effective to screen for HAV before
vaccination.
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d.
Immunization
In Developed countries vaccination of high risk groups:
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persons at increased risk for HAV infection :
- chronic liver disease and clotting disorders
- homosexuals
- Iv drug users
- travelers to endemic areas (could be given with IG if
travel in <2weeks)
children in communities with consistently elevated rates of
hepatitis A.
IG to Close personal contacts (household, sexual, institutional) of
persons with HAV is recommended as early after exposure as possible.
- Could be given with the vaccine on separate sites
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Passive immunization (IG):
- When administered before exposure or during the early IP, it is
effective in preventing clinical hepatitis A.
B. Control of patient & contacts
a. Report the disease to local health authority
b. Isolation of confirmed cases/ enteric precautions for 1
week post jaundice; but longer in outbreaks in
neonatal ICU.
c. Concurrent disinfection: Sanitary disposal of feces, urine,
and blood
d. Immunize contacts (vaccine & IG within 2 weeks post
exposure) after serology confirmation of HAV infection
in index patients (IGM anti-HAV testing).
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Hepatitis B virus (HBV)
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1.
Epidemiology
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About 10% of children and 30-50% of adults with acute HBV
infection show icteric disease.
Case fatality is 1%, higher in >40 y.
Chronic infection is found in 0.5% of adults in North America and
0.1-20% in other parts of the world.
After acute infection, the risk of chronic infection (CI) is inversely
related to age.
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CI occurs among 90% of infants infected at birth,
20-50% of children infected between 1-5 years, and
1-10% infected of older children and adults.
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15-25% of CI patients will die prematurely of cirrhosis or
hepatocellular carcinoma (HC).
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HBV may be the cause of 80% of all cases of HC worldwide.
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The risk of HBV infected men transmitting it to women is 3 times
more than it is women to men.
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Occurance
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Worldwide and endemic
2 billions persons have been infected with 350 millions chronically
infected
Each year 1 million persons die of HBV and 4 million acute clinical
cases occur.
In highly endemic countries (HBsAg >8%), most infections occur
during infancy and early childhood.
In intermediate endemic countries (HBsAg 2-7%) infection occur in
all age groups.
In Low endemic countries, infections is more among young adults;
especially high risk groups.
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Mode of Transmission
Body substances (blood/products, saliva, semen, vag. secretions,
unfixed tissues, CSF, pleural/peritoneal/pericardial/synovial/
amniotic fluids transmitted through
percutaneous (IV, IM, SC, Intradermal) or
permucosal route
Inanimate objects (HBV stable for 1 week at room temprature).
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Major modes of transmission:
 Anal intercourse,
 In household, HBV transmitted from child to child.
 Sharing razors and toothbrushes.
 Perinatal transmission is common (85% of babies born to mothers
positive for HBsAg).
 Injecting drug users
 Nosocomial exposure such as : transfusion of blood/blood products,
hemodialysis, acupuncture, needle stick.
 IG, heat treated plasma protein, albumin, and fibrinolysin are safe.
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Methods of control
A.
Preventive measures.
1. Vaccine:
one from plasma of HBsAg +ve,
2nd from recombinant DNA (rDNA).
Combined passive-active immunoprophylaxix is more effective
but expensive.
i.
In all countries, routine infant immunization should be the
primary strategy to prevent HBV infection.
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In endemic countries, routine infant immunization rapidly eliminates
transmission.
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For low/ intermediate endemicity countries immunization extended
for older children, adolescents, and adults may be more desirable
strategy.
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Strategies that ensure high vaccine coverage of successive
age group cohorts are the most effective in eliminating HBV
transmission.
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In addition, immunization strategies can be targeted to
high risk groups, which account for most cases among
adolescents and adults.
ii.
Testing to exclude people with pre-existing anti-HBs or antiHBc is not required but may be a cost saving method among
children and adults where level of infection is high.
iii.
Immunity lasts fro 15 years.
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Pregnancy is not a contraindication for giving vaccine.
v.
Vaccine schedule vary by country. What is in Jordan?
Single antigen preservative-free HB vaccine is now available.
iv.
2.
The current WHO HB prevention strategies based on routine
universal newborn/infant immunization. The greatest fall in
incidence of HB is in countries with high vaccine coverage at
birth and infancy.
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3.
Persons at high risk should routinely receive pre-exposure HB
immunization include:
a. people recently acquired STDs and people have history of
> 1 sexual partner in the past 6 months;
b. men have sex with men;
c. sexual partners and household contacts of HBsAg +ve
persons;
d. inmates in jails ,prisons;
e. health care and public safety workers involved in
handling blood/body fluids;
f. Hemodialysis;
g. pts with bleeding disorders receiving blood;
h. travelers intend to spend >6moths in countries of high rate
of CI (>2%) and will have close contact with local people.
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4.
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In blood banks, all blood tested for HBsAg.
Reject donors with history of viral hepatitis, drug injection,
receive blood or tattooing in the last 6 months.
Health care workers are not to perform surgery or similar
treatments for patients.
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B. Control of patient, contacts and the immediate
environment.
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Report, class 2.
Isolation: universal precautions against blood/products.
Concurrent disinfection: of equipment contaminated
Quarantine: NA
Immunization of contacts
Infants of mothers with HBsAg +ve to be given single dose of vaccine
within 12 hours of birth, and where available .5 ml HBIG at separate
site, 2nd and 3rd doses at 1-2 and 6 months later.
Investigation of contacts
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Hepatitis C virus (HCV)
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1.
Epidemiology
Occurrence
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WHO estimate 130-170 million (2-3%) of world population
are chronically infected. Most regions anti-HCV prevalence
is <2.5%, but 2.5-4.9% in western pacific, and 1-12% in middle
east.
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HCV accounts for 40% of chronic liver disease.
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Mode of Transmission
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Primarily parenteral but sexual and mother-to-child has been
documented
1970s 10% per chronically infused patients receiving screened blood
developed hepatitis.
1980s with HIV screening this figure dropped to 5%.
1980-1990 HCV was discovered and this figure dropped even further
due to testing for anti HCV.
Discovery of 2nd generation of anti HBc assays (automated PCR
testing for HCV RNA) reduced infection to 1/100,000.
HBC can be transmitted by other percutaneous routes, drug users.
HBC can be transmitted by occupational exposure to blood and tend
to increase in hemodialysis units.
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Sexual and perinatal mode is theoretically valid but not sufficient
enough (account for 5% of all cases).
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Infection of HCW is like general population.
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No infection from breast feeding.
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No infection to household contacts.
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Methods of control
1.
Preventive measure
General control measures against HBV apply
IG is not effective
No vaccine is yet developed
strict measures of screening donated blood
Counseling with high risk groups including health care workers.
2. Control of patient, contacts, and immediate environment
General control measures against HBV apply
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