Download Hepatitis A virus

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Identify the type of hepatitis virus causing a hepatitis infection.
Screen people (such as doctors, dentists, and nurses) who have an
increased chance of getting hepatitis virus infection.
Screen potential blood donors and donor organs to prevent the
spread of hepatitis .
Find out whether a person has antibodies after getting a hepatitis
vaccine .
Find out if a hepatitis virus infection is the cause of abnormal liver
function tests.
HAV causes hepatitis A (The most common
of the known types of viral hepatitis)
A member of the enteroviruses
(picornaviridae family).
Single -stranded RNA genome.
Icosahedral, naked and 27 – 32 nm
in diameter
Have short incubation period: 2 – 6 weeks.
HAV is transmitted by fecal-oral route.
Transmitted person-to-person by ingestion of
contaminated food or water or through direct
contact with an infectious person.
Virus appears in the feces roughly 2 weeks
before the appearance of symptoms, so in this
period the virus is infective.
Children are the most frequently infected
group.
A tiny amount of the virus will cause the infection.
Unlike HBV, HAV is rarely transmitted via the blood, and chronic infection
doesn’t occur.
Acute, there is no chronic carrier state occurs, and there’s no predisposition
to hepatocellular carcinoma and the complications are rarely serious.
The infection with this virus for the first time does not provide protection
from infection again.
Personal hygiene, such as careful hand washing, can minimize the risk of the
virus transmission to other person.
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Detection of the virus in the feces only in the first 2 weeks of infection
by used immune-electron microscopy.
Liver function test will show elevated transaminases (ALT, AST, LDH,
ALP) and elevated measurements of bilirubin in blood & Urine.
RIA or ELISA for IgM in the first 2-3 weeks and later for IgG.
HAV Rapid IgM or IgG -Assay
Isolation of the virus in cell culture but usually not available in the
clinical laboratory.
There is no specific treatment for HAV and most people
fight off the virus naturally (self-limited), returning to full
health within a couple of months.
The doctor will advise avoiding alcohol and fatty foods as
these can be hard for the liver to process and may
exacerbate the inflammation.
Patients should get plenty of rest and eat a nutritious diet.
They should also ensure they do not spread HAV by
washing their hands after using the toilet and before
preparing food.
Patients with more severe symptoms may be monitored in
hospital for a short period.
 Belongs to the hepadnaviridae family.
 Spherical, double- shelled DNA containing
particles.
 Icosahedral, enveloped and 42 nm in
diameter.
 Incubation period: 2 – 6 months (50 - 180
days).
Subviral lipoprotein particles (Excess envelope)
1- Vertical transmission
From mother to baby
4- Sharing contaminated
needles or other equipment
2- Sexual transmission
3- Blood transfusion
5- Parenteral transmission
By using non-sterilized equipment for tattooing,
acupuncture or body piercing
The clinical appearance of hepatitis B disease is similar to that
of hepatitis A. However, with hepatitis B, symptoms tend to be
more severe and life threatening.
1. A short, mild, flu-like illness.
2. Nausea.
3. Fatigue.
4. Abdominal pain.
5. Weight loss.
6. Jaundice.
7. Itchy skin.
If a person lives with hepatitis B infection for a number of years
then they may develop the following complications:
Chronic hepatitis.
Liver cirrhosis.
Liver cancer.
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Liver function tests, abnormally elevated transaminases (ALT and AST),
bilirubin, alkaline phosphatase (ALP) and lactate dehydrogenase (LDH).
2. The presence of HBsAg confirms diagnosis as it appears in most patients ,
tested by ELISA and RIA.
3. Serological testing via Hepatitis marker testing
4. Detection of viral DNA load in the serum which is a strong evidence that
the infectious virions are present.
5. Liver biopsy and PCR.
Stage of disease
Incubation period
Acute hepatitis
Chronic carrier state
“low infectivity”
Chronic active state
“high infectivity”
Convalescence
Past infection
Vaccination
HBsAg HBs Ab Hbe Hbe Ab HBcAb
Ag
“IgM”
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HBcAb
“Total”
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Hepatitis B vaccine is pure HBsAg produced by
recombinant DNA.
 The vaccination schedule most often used for
adults and children has been three intramuscular
injections, the second and third administered 1 and
6 months after the first.
 A blood test is taken once the course of injections
is completed to check they have worked.
 Immunity should last for at least 5 years.
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1.Acute hepatitis B
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If someone is exposed to the hepatitis B virus in the previous seven
days or less, he can receive an injection of hepatitis B immune globulin
that may prevent developing the disease.
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Besides this, there is no treatment for acute hepatitis B.
Prevent further liver damage
2. Chronic hepatitis B
Two types of treatment exist
Interferon which is a medication administered by a needle and
 Antiviral medicines that are taken by mouth
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These treatments do not provide a cure, but they offer control of
the virus so that further damage to your liver can be prevented.
Regardless of whether the infection is producing symptoms or not, the patient will
be advised to avoid alcohol, get plenty of rest and maintain a healthy diet
Belong to the flaviviridae family.
Enveloped, RNA containing particles.
Icosahedral with 60 – 70 nm in diameter.
Incubation period: 15 – 150 days.
Transmission of hepatitis C virus is similar to hepatitis B virus, can
transmit via any activity where blood may be involved
However ; the modes of sexual transmission and passing the virus
from an infected mother to her baby via breast milk are much less
common.
Notice
Chronic infections occur in 75-85% of infected persons.
And about 20% of individuals who become infected with HCV will clear
the virus from their body within 6 months, though this does not mean
they are immune from future infection with HCV.
1. Serological blood tests used to detect antibodies to HCV with ELISA
Technique.
This test doesn’t distinguish between an acute, chronic, or resolved infection.
2. Using molecular nucleic acid testing methods such as :
- RT-PCR (polymerase chain reaction)
assay)
- RIBA (recombinant immunoblot
- TMA (transcription mediated amplification) - b-DNA (branched DNA)
These tests have the capacity to detect not only whether the virus is present,
but also to measure the amount of virus present in the blood
(the HCV viral load).
3. The HCV viral load is an important factor in monitoring
the success to interferon-based therapy
4. Liver function tests.
5. Liver biopsy.
Hepatitis C does not always require treatment as the immune response
in some people will clear the infection, and some people with chronic
infection do not develop liver damage.
When treatment is necessary, the goal of hepatitis C treatment is cure.
The cure rate depends on several factors including the strain of the
virus and the type of treatment given.
Treatment combines the antiviral drugs interferon and ribavirin.
Notice: There is no vaccine for Hepatitis C virus.
Hepatitis D virus
HDV is unusual in that it can replicate only in cells also
infected with HBV because HDV uses HBsAg as its envelope
protein.HBV is thereforethe helper virus for HDV.
HDV is transmitted by the same means as HBV.
Hepatitis E virus
HEV is transmitted by fecal-oral route and it is a common
cause of water-borne hepatitis in many developing
countries.
Clinically the disease resembles hepatitis A.
Characteristics of HIV:
The causative agent of acquired
immunodeficiency syndrome (AIDS).
 Belong to the lentivirus subfamily of the
retrovidridae family.
 Enveloped, icosahedral, RNA containing
particles.
 Have envelope glycoproteins: gp120 and
gp41.
 Infect immune system (T helper
lymphocyte; CD4).
 Incubation period: 3 – 5 years.
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GP 41
Transmembranous
glycoprotein
GP 120
Doking
glycoprotein
Mode of transmission of HIV:
In general, transmission of HIV follows the pattern of HBV,
except that the dose of HIV infection required to cause infection
is much higher than HBV.
Sexual contact (primarily).
 Sharing contaminated intravenous needles.
 Infected mother to her baby, either across the placenta,
at birth, or via breast milk.
 Blood transfusions and tissue transplantation.
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Signs and symptoms of HIV:
Often people who are infected with
HIV don't have any symptoms at all.
 It is important to remember that a
person who has HIV can pass on the
virus immediately after becoming
infected, even if they feel healthy.
 It's not possible to tell just by looking
if someone has been infected with
HIV
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Common opportunistic infection in AIDS
AIDS:
 This is the stage of HIV infection that occurs when your immune
system is badly damaged (CD4 <200 cells/mm3) and you become
vulnerable to opportunistic infections.
 Without treatment, people who progress to AIDS typically survive
about 3 years. Once you have a dangerous opportunistic illness, lifeexpectancy without treatment falls to about 1 year.
 Antiretroviral therapy administration and a low viral load, the
patient may enjoy a near normal life span and most likely never
progress to AIDS.
Laboratory diagnosis of HIV:
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Antibody detection:
• ELISAs are the most frequently used method for screening of blood
samples for HIV antibody but false positive and false negative
reactions may occur.
• Another test systems available include passive particle agglutination,
immunofluorescence, Western blots and RIBA bioassays.
• Western blots are regarded as the gold standard
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Antigen screening:
• HIV antigen can be detected early in the course of HIV
infection before the appearance of antibody.
• It is undetectable during the latent period (antigenantibody complexes are present) but become detectable
during the final stages of the infection.
• Capsid P24 antigen tests measure one of the proteins
found on HIV virus by ELISA assays.
 Virus isolation is accomplished by the cultivation of the patient's
lymphocytes with fresh peripheral blood cells of healthy donors or
with suitable culture lines such as T-lymphomas.
 However virus isolation is tedious and time consuming (weeks),
therefore virus isolation is mainly used for the characterization of
the virus.
• This can be accomplished by PCR techniques due to its
extremely high sensitivity.
• HIV viral load in serum may be measured by assays
which detect HIV-RNA e.g. RT-PCR.
• HIV viral load has now been established as having good
prognostic value, and in monitoring response to antiviral
chemotherapy.
• Patients with a low viral load during the incubation
period had a better prognosis than those with a high viral
load.
CD4 count gives an indication of the stage of disease.
Early immune deficiency
CD4 count > 500 cells/mm3
intermediate immune deficiency
CD4 count (200-500) cells/mm3
Advance immune deficiency
CD4 count < 200 cells/mm3
“The measurement of HIV viral load tells us where the disease
is going, whereas CD4 count tells us where the disease is at
this moment”