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Viral Hepatitis. Why Hepatitis virus testing is done ?. 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.
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Viral Hepatitis
Why Hepatitis virus testing is done ? • 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.
Characteristics of HAV • HAV causes hepatitis A (The most common of the known types of viral hepatitis) • Have short incubation period: 2 – 6 weeks.
HAV transmission • 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.
Laboratory diagnosis of HAV: • 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.
Characteristics of HBV: • Incubation period: 2 – 6 months (50 - 180 days).
HBV transmission: 1- Vertical transmission From mother to baby 2- Sexual transmission 3- Blood transfusion 5- Parenteral transmission By using non-sterilized equipment for tattooing, acupuncture or body piercing 4- Sharing contaminated needles or other equipment
Signs and symptoms of HBV: 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. • A short, mild, flu-like illness. • Nausea. • Fatigue. • Abdominal pain. • Weight loss. • Jaundice. • 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.
Laboratory diagnosis of HBV: • Liver function tests, abnormally elevated transaminases (ALT and AST), bilirubin, alkaline phosphatase (ALP) and lactate dehydrogenase (LDH). • The presence of HBsAg confirms diagnosis as it appears in most patients , tested by ELISA and RIA. • Serological testing via Hepatitis marker testing • Detection of viral DNA load in the serum which is a strong evidence that the infectious virions are present. • Liver biopsy and PCR.
HBs Antigen (HBsAg): Part of the virus surface. Appears 2–6 months after infection and proves that someone has acute or chronic hepatitis B. • If HBsAg disappears and protective antibodies appear (HBsAg negative, anti-HBs positive), this is considered a “cure”. • HBs antibody (anti-HBs): The immune system creates this antibody to destroy the HBsAg of the virus. Anti-HBs appears if an infected person clears their virus (”cure”), or if a healthy person is successfully vaccinated. • HBc antibody (anti-HBc): Created by the immune system against the core of the hepatitis B virus. Always becomes positive in an infection and stays for life, no matter if the infection is cleared or becomes chronic
HBeantigen (HBeAg): can only be found in the original ”wild type“ of the hepatitis B virus. HBeAg is an indirect sign that the virus is replicating actively. However, HBeAg is also a vulnerable part of the virus. The immune system might create anti-HBe antibodies and destroy HBeAg.This is not a cure, but the virus is being controlled by the immune system, and cannot replicate well anymore • HBeantibody (anti-HBe): Specialized to destroy the HBe antigen. In chronic hepatitis B, these antibodies can damage the virus and inhibit itsreplication for many years or even decades: HBeAg negative, anti-HBe positive. This is called HBeAg seroconversion. This is not a cure, but the virus is at least being controlled by the immune system.
HBV immunization: • 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.
Can hepatitis B be treated 1.Acute hepatitis B • 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. • 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 needleand • Antiviral medicines that are taken by mouth • 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 wheatherthe infection is producing symptoms or not, the patient will be advised to avoid alcohol, get plenty of rest and maintain a healthy diet
Characteristics of HCV: • Incubation period: 15 – 150 days.
HCV transmission: • 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.
Laboratory diagnosis of 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) • RIBA (recombinant immunoblot assay) • 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).
Additional tests 3. The HCV viral load is an important factor in monitoring the success to interferon-based therapy 4. Liver function tests. 5. Liver biopsy.
Treatment for HCV: • 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.
None A, none B hepatitis viruses 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 therefore the 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: • Have envelope glycoproteins: gp120 and gp41. • Infect immune system (T helper lymphocyte; CD4). • Incubation period: 3 – 5 years. 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.
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 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, life-expectancy 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: 1- Serological screening: • 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
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 (antigen-antibody 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.
2-Virus isolation: • 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. 3. Demonstration viral nucleic acid: • This can be accomplished by PCR techniques due to its extremely high sensitivity.
4. HIV viral load: • 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: CD4 count gives an indication of the stage of disease. “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”
