Etiology And Mechanisms Of Hbv Infection
Hepatitis B virus
HBV is classified in the family Hepadnaviridae. It is a very small, partially double-stranded DNA virus. Humans are known to be the only natural host. HBV reaches the liver through the systemic circulation and can only replicate in hepatocytes . Since HBV is a hepatotropic virus, injury to the liver results from the immune-mediated destruction of infected hepatocytes .
The infectious HB virion has a diameter of 42-47 nm and is a double-shelled particle in serum. Its concentration can be as high as 108 virions per mL . The infectious HB virion consists of an outer lipoprotein coat containing hepatitis B surface antigen . HBsAg surrounds an inner nucleocapsid composed of hepatitis B core antigen that encapsidates the HBV genome and DNA polymerase .
Genome structure and proteins
FIGURE 1: Structure and organization of the HBV genome . The four protein-coding regions are shown by semicircular arrows. They include the precore and core gene the polymerase gene the X gene and the envelope genes pre-S1, pre-S2, and S . The positions of the direct repeats are indicated. Genome positions may change, depending on the HBV genotype . Abbreviations: HBV, hepatitis B virus P gene, the polymerase gene C gene, the core gene S gene, the surface gene.
Natural history of HBV infection
The natural history of chronic HBV infection can be separated into five stages, which are not necessarily sequential . These stages are summarized in Table 1 .
Study Population And Clinical Methods
During the calendar year 1996, a total of 2098 patients visited three STD clinics of the National AIDS Research Institute in Pune. As a part of the ongoing study of HIV transmission among people with high risk behaviour, these patients were offered serological screening for HIV-1 and HIV-2 infection and STD diagnosis and treatment. People seronegative for HIV were invited to participate in a prospective study of HIV acquisition and instructed to return every 3 months for follow up. Seropositive patients were also encouraged to come for follow up. After informed consent, patients were administered a structured questionnaire, which included data on demographics, STD and medical history, sexual behaviour, and reproductive history in female patients. Presumptive diagnosis of sexually transmitted disease was based on detailed physical examination and clinic based laboratory tests. The diagnosis and treatment of STDs was administered in accordance with WHO guidelines.
Of the 2098 patients screened in the STD clinics, 497 , who returned for at least one follow up visit till December 1998, were included in the present analyses.
What Treatments Are Available For Chronic Hepatitis B If Medications Dont Work
If you have advanced hepatitis B, you might also become a candidate for a liver transplant. This path does not always result in a cure because the virus continues in your bloodstream after a transplant. To prevent being infected again after your transplant, you may be prescribed hepatitis B immunoglobulin with an antiviral agent.
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Postvaccination Serologic Testing For Response
Postvaccination serologic testing for immunity is unnecessary after routine vaccination of adolescents or adults. However, such testing is recommended for persons whose subsequent clinical management depends on knowledge of their immune status. Persons recommended to receive postvaccination serologic testing include health care personnel and public safety workers, persons with HIV infection, sex and needle-sharing partners of HBsAg-positive persons, hemodialysis patients and others who might require outpatient hemodialysis , and other immunocompromised persons .
If indicated, anti-HBs testing should be performed 12 months after administration of the last dose of the vaccine series. Persons determined to have anti-HBs levels of < 10 mIU/mL after the primary vaccine series should be revaccinated with a 3-dose series and tested again for anti-HBs 12 months after the third dose. Persons who do not respond to revaccination should be tested for HBsAg and HBc. If HBsAg positive, persons should receive recommended management . If HBsAg negative, persons should be considered susceptible to HBV infection and counseled about precautions for preventing HBV infection and the need for HBIG PEP for any known exposure. If isolated anti-HBc positive , persons will need further assessment to rule out occult HBV infection and are at higher risk for reactivation if exposed to immunosuppressants.
Can You Get Rid Of Hepatitis B
There is no cure for hepatitis B, but in some people, it goes away on its own. Some people have it for the rest of their lives. There is medicine that can help the liver of people who have chronic hepatitis. Even if you dont have symptoms, you can still pass it on to others if you have unprotected sex with them.
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Symptoms Of Hepatitis B
Many people with hepatitis B will not experience any symptoms and may fight off the virus without realising they had it.
If symptoms do develop, they tend to happen 2 or 3 months after exposure to the hepatitis B virus.
Symptoms of hepatitis B include:
- flu-like symptoms, including tiredness, a fever, and general aches and pains
- loss of appetite
- tummy pain
- yellowing of the skin and eyes
These symptoms will usually pass within 1 to 3 months , although occasionally the infection can last for 6 months or more .
How Is It Transmitted
Hepatitis B is highly infectious, and is spread from one person to another through exposure to infected blood and body fluids . It can be spread through:
- blood transfusions or organ transplantation in countries where blood or blood products have not been properly screened for hepatitis B and other viruses transmitted through blood
- unprotected sex with an infected person
- sharing needles or equipment for injecting drugs
- unsterilized medical/dental equipment and shared/contaminated materials or equipment used for tattooing, body piercing or acupuncture
- sharing toothbrushes or razors
- household contact between family members
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Hepatitis B Surface Antigen Test
A hepatitis B surface antigen test shows if youre contagious. A positive result means you have hepatitis B and can spread the virus. A negative result means you dont currently have hepatitis B. This test doesnt distinguish between chronic and acute infection. This test is used together with other hepatitis B tests to determine the .
Epidemiology: Incidence And Prevalence
Incidence: worldwide view and HIV/HBV coinfection
More than one third of the worlds population are estimated to be infected with HBV. About 5% of the worlds population are chronic carriers of HBV, and HBV infection causes more than one million deaths every year . The HBsAg carrier rate varies from 0.1% to 20% of different populations worldwide. In low-risk regions, the highest incidence of infection is seen in teenagers and young adults.
Based on the data from Western cohorts, HIV/HBV coinfection has a profound impact on almost every aspect of the natural history of HBV infection . The consequences include higher rates of chronicity after acute HBV infection, higher levels of HBV replication and rates of reactivation, less spontaneous clearance, higher rates of occult HBV infection , more rapid progression to cirrhosis and HCC, higher rates of liver-related mortality, and decreased treatment response compared with individuals without HIV coinfection . Recent longitudinal cohort studies have found that coinfection with HBV also can lead to increased rates of progression to acquired immune deficiency syndrome -related outcomes and all-cause mortality . An estimated 5% to 15% of the 34 million HIV-infected individuals worldwide are coinfected with HBV, as a chronic infection . The burden of coinfection is greatest in Southeast Asia and sub-Saharan Africa .
Prevalence: international statistics
HBV serotypes and genotypes
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What Are The Symptoms Of Hepatitis B
Many people with hepatitis B dont have any symptoms. If you do get symptoms you may not notice them until two or three months after infection and they can last up to three months. There are two types of infection acute and chronic.
Acute symptoms include:
- flu-like symptoms, including tiredness, fever and aches and pains
- feeling and/or being sick
- jaundice, meaning your skin and the whites of your eyes turn yellow
- dark urine
- pale faeces .
People who cant fight off acute infection after six months, such as babies, young children and people with a weakened immune system because of HIV, can go on to develop chronic hepatitis B. This is when people are at higher risk of liver failure, liver disease and cancer of the liver.
Exposure To A Source Who Is Hbsag Positive
Unvaccinated persons or persons known not to have responded to a complete hepatitis B vaccine series should receive both HBIG and hepatitis vaccine as soon as possible after a discrete, identifiable exposure to blood or body fluids that contain blood from a person with HBsAg . Hepatitis B vaccine should be administered simultaneously with HBIG at a separate anatomic site, and the vaccine series should be completed by using the age-appropriate vaccine dose and schedule . Exposed persons who are not fully vaccinated because they have not completed the vaccine series should receive HBIG and complete the vaccine series. Persons who have written documentation of a complete hepatitis B vaccine series who did not receive postvaccination testing should receive a single vaccine booster dose. Exposed persons who are known to have responded to vaccination by postvaccination testing are considered protected therefore, they need no additional doses of vaccine or HBIG. All persons with an occupational exposure to blood or body fluids that contain HBV should be managed according to guidelines .
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Should I Be Screened For Hepatitis B
Screening is testing for a disease in people who have no symptoms. Doctors use blood tests to screen for hepatitis B. Many people who have hepatitis B dont have symptoms and dont know they are infected with hepatitis B. Screening tests can help doctors diagnose and treat hepatitis B, which can lower your chances of developing serious health problems.
Your doctor may recommend screening for hepatitis B if you9,14
- are pregnant
- were born in an area of the world where 2 percent or more of the population has hepatitis B infection, which includes Africa, Asia, and parts of the Middle East, Eastern Europe, and South America
- didnt receive the hepatitis B vaccine as an infant and have parents who were born in an area where 8 percent or more of the population had hepatitis B infection, which includes sub-Saharan Africa and parts of Asia
- are HIV-positive
- are a man who has sex with men
- have lived with or had sex with a person who has hepatitis B
- have an increased chance of infection due to other factors
Hepatitis A And B Immunization In Persons Being Evaluated For Sexually Transmitted Diseases
- H. Hunter HandsfieldCorrespondenceAddress correspondence to H. Hunter Handsfield, MD, Harborview Medical Center, Box 359777, 325 Ninth Avenue, Seattle, Washington 98106.AffiliationsCenter for AIDS and STD, University of Washington, and the Department of Medicine, Harborview Medical Center, Seattle, Washington, USA.
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What Is My Risk
Your risk depends of several factors: destination, length of stay, what you do when you are travelling and whether you have direct contact with blood or other body fluids. In certain destinations, your risk may be higher, as some areas have higher numbers of people with chronic hepatitis B in the general population.
The risk increases with certain activities, such as unprotected sex, sharing needles, tattooing and acupuncture.
Aid and health care workers and anyone who receives medical or dental care with unsterilized or contaminated equipment in a country where hepatitis B occurs are also at greater risk.
Hepatitis B Symptoms & Treatment
- Hepatitis B is a virus found in infected blood, semen and vaginal fluids.
- Its a sexually transmitted infection that can be passed on through unprotected sex. You can also get it from contaminated needles and syringes. Its also commonly passed on from a mother to her baby during birth.
- There is a vaccine to prevent hepatitis B, which is routinely offered to infants as well as at-risk groups.
- You can prevent hepatitis B by practising safer sex, never sharing needles and syringes, and avoiding unlicensed tattoo parlours and acupuncturists.
- Most people dont need treatment for acute hepatitis B. If the infection becomes chronic, there is no cure, but it can be managed with treatment.
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Which Stds Have Vaccines
Some STDs, such as such as gonorrhea, Chlamydia, and syphilis, are caused by bacteria. They are usually effectively treated with antibiotics, although many patients do not know that they are infective and can spread the disease to other partners. The availability of treatments means that the need for vaccines against these diseases is not a top priority, although the increased resistance of gonorrhea to antibiotics may lead to a shift in priorities.
Viral STDs are often highly persistent despite current therapeutic options or have no acceptable treatment available. Therefore, vaccines for certain viral STDs are in use, and others are in development.
How Is Hepatitis B Spread
You can become infected with hepatitis B through exposure to blood, semen and other bodily fluids of an infected person. You can get the infection by:
- Having unprotected sex.
- Sharing or using dirty needles for drug use, tattoos or piercing.
- Sharing everyday items that may contain body fluids, including razors, toothbrushes, jewelry for piercings and nail clippers.
- Being treated medically by someone who does not use sterile instruments.
- Being bitten by someone with the infection.
- Being born to a pregnant woman with the infection.
Hepatitis B is not spread by:
- Kissing on the cheek or lips.
- Coughing or sneezing.
- Hugging, shaking hands or holding hands.
- Eating food that someone with the infection has prepared.
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Is Hepatitis B Contagious
Hepatitis B is highly contagious. It spreads through contact with infected blood and certain other bodily fluids. Although the virus can be found in saliva, its not spread through sharing utensils or kissing. It also doesnt spread through sneezing, coughing, or breastfeeding. Symptoms of hepatitis B may not appear for 3 months after exposure and can last for 212 weeks. However, you are still contagious, even
To screen for hepatitis B, your doctor will perform a series of blood tests.
When To Get Medical Advice
Hepatitis B can be serious, so you should get medical advice if:
- you think you may have been exposed to the hepatitis B virus emergency treatment can help prevent infection if given within a few days of exposure
- you have symptoms associated with hepatitis B
- you’re at a high risk of hepatitis B high-risk groups include people born in a country where the infection is common, babies born to mothers infected with hepatitis B, and people who have ever injected drugs
A blood test can be carried out to check if you have hepatitis B or have had it in the past.
The hepatitis B vaccine may also be recommended to reduce your risk of infection.
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Treatment Options For Hepatitis B
Acute hepatitis B usually doesnt require treatment. Most people will overcome an acute infection on their own. However, rest and hydration will help you recover.
Antiviral medications are used to treat chronic hepatitis B. These help you fight the virus. They may also reduce the risk of future liver complications.
You may need a liver transplant if hepatitis B has severely damaged your liver. A liver transplant means a surgeon will remove your liver and replace it with a donor liver. Most donor livers come from deceased donors.
What Is Chronic Hepatitis B
Doctors refer to hepatitis B infections as either acute or chronic:
- An acute HBV infection is a short-term illness that clears within 6 months of when a person is exposed to the virus.
- A person who still has HBV after 6 months is said to have a chronic hepatitis B infection. This is a long-term illness, meaning the virus stays in the body and causes lifelong illness. An estimated 850,000 to more than 2 million people in the U.S. have chronic HBV.
The younger someone is when infected, the greater the chances for chronic hepatitis B.
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What Causes Hepatitis B
The hepatitis B virus causes hepatitis B. The hepatitis B virus spreads through contact with an infected persons blood, semen, or other body fluids. Contact can occur by
- being born to a mother with hepatitis B
- having unprotected sex with an infected person
- sharing drug needles or other drug materials with an infected person
- getting an accidental stick with a needle that was used on an infected person
- being tattooed or pierced with tools that were used on an infected person and werent properly sterilized, or cleaned in a way that destroys all viruses and other microbes
- having contact with the blood or open sores of an infected person
- using an infected persons razor, toothbrush, or nail clippers
You cant get hepatitis B from
- being coughed on or sneezed on by an infected person
- drinking unclean water or untreated water that has not been boiled
- eating food that is unclean or has not been properly cooked
- hugging an infected person
- shaking hands or holding hands with an infected person
- sharing spoons, forks, and other eating utensils
- sitting next to an infected person
Mothers who have hepatitis B can safely breastfeed their babies. If a baby receives hepatitis B immune globulin and starts receiving the hepatitis B vaccine to prevent hepatitis B infection shortly after birth, hepatitis B is unlikely to spread from mother to child through breastfeeding.15