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Yellow Fever. Common Questions [ ]. Do Vaccines Cause Autism? Have I Been Vaccinated? Misconceptions about Vaccines. Top 20 Questions about Vaccination. Vaccination for Rare Diseases. Why Vaccinate? Correct This antigen is a surface protein of the hepatitis B virus. Symptoms and Causative Agent Hepatitis is a general term for inflammation of the liver, which may result from infectious or non-infectious causes. HBV remains infectious for at least 7 days on environmental surfaces and is transmissible in the absence of visible blood.
It replicates in hepatocytes through a unique reverse transcription process. The clinical course of acute hepatitis B is indistinguishable from that of other types of acute viral hepatitis. The incubation period typically ranges from 60 to 90 days. Clinical signs and symptoms occur more often in adults than in infants or children; infants and young children usually are asymptomatic.
The preicteric, or prodromal, phase from initial symptoms to onset of jaundice usually lasts 3 to 10 days. It is nonspecific and is characterized by abrupt onset of fever, malaise, anorexia, nausea, abdominal discomfort, and dark urine beginning 1 to 2 days before the onset of jaundice. The icteric phase is variable but usually lasts from 1 to 3 weeks and is characterized by jaundice, light or gray stools, hepatic tenderness, and hepatomegaly splenomegaly is less common.
During convalescence, malaise and fatigue may persist for weeks or months, while jaundice, anorexia, and other symptoms disappear. Most acute HBV infections in adults result in complete recovery with elimination of HBsAg from the blood and the production of anti-HBs, creating immunity to future infection.
Perinatal transmission from mother to infant at birth vertical transmission is highly efficient. Although the consequences of acute HBV infection can be severe, most of the serious complications associated with HBV infection are due to chronic infection.
The proportion of persons with acute HBV infection who progress to chronic infection varies with age and immune status. Persons with chronic infection are often asymptomatic and may not be aware they are infected; however, they are capable of infecting others and have been referred to as carriers.
Chronic infection is responsible for most HBV-related morbidity and mortality, including chronic hepatitis, cirrhosis, liver failure, and HCC. An estimated million persons worldwide are living with HBV infection. HBV infection is an established cause of acute and chronic hepatitis and cirrhosis. The frequency of infection and patterns of transmission vary in different parts of the world.
In these high-prevalence areas, most infections are acquired at birth or during early childhood when the risk of developing chronic infections is greatest. In these areas, because most infections are asymptomatic, very little acute disease related to HBV occurs, but rates of chronic liver disease and liver cancer among adults are very high.
Infection occurs primarily during adulthood, and only 0. Diagnosis is based on clinical, laboratory, and epidemiologic findings. HBV infection cannot be differentiated based on clinical symptoms alone, and definitive diagnosis depends on the results of serologic testing. Serologic markers of HBV infection vary depending on whether the infection is acute or chronic.
The presence of HBsAg indicates that a person is infectious, regardless of whether the infection is acute or chronic. Transient HBsAg positivity can occur up to 18 days following vaccination up to 52 days among hemodialysis patients and is clinically insignificant.
Anti-HBs is a protective, neutralizing antibody. The presence of anti-HBs following acute HBV infection generally indicates recovery and immunity against reinfection. Anti-HBc generally persists for life. Persons who are HBsAg-negative and anti-HBc-positive can experience reactivation of infection during chemotherapy or immunosuppressive therapy, with reappearance of HBsAg.
IgM anti-HBc appears in persons with acute disease about the time of illness onset and indicates recent infection with HBV. IgM anti-HBc is generally detectable 4 to 6 months after onset of illness and is the best serologic marker of acute HBV infection. HBeAg is a marker that is associated with a high number of infective HBV particles in the serum and a higher risk of infectivity.
Anti-HBe correlates with a reduction of replicating virus and lower infectivity, although reversion to HBeAg positivity can occur.
There is no specific therapy for acute HBV infection. Treatment is supportive. These persons are at high risk for liver-related morbidity. Maternal therapy is generally discontinued at birth to 3 months postpartum. Persons with acute or chronic HBV infections should prevent their blood and other potentially infective body fluids from contacting other persons. They should not donate blood or share toothbrushes or razors with household members.
In health care settings, patients with HBV infection should be managed with standard precautions. HBV infection occurs worldwide. The frequency of infection varies in different parts of the world but is more common in some countries in Asia, Africa, South America, and the Caribbean.
HBV infection affects humans. Additionally, some primates chimpanzee, gorilla, orangutan, gibbon in Africa and Southeast Asia are infected with HBV. The highest concentrations of virus are in blood and serous fluids; lower titers are found in other fluids, such as saliva, tears, urine, and semen. Semen is a vehicle for sexual transmission and saliva can be a vehicle of transmission through bites; other types of exposure e.
HBsAg is also found in other body fluids e. However, most body fluids are not efficient vehicles of transmission unless they contain blood because they contain low quantities of infectious HBV. In the United States, the most important routes of transmission are injection-drug use, perinatal, and sexual contact with an infected person. Fecal-oral transmission does not appear to occur. However, transmission occurs among men who have sex with men MSM , possibly via contamination from asymptomatic rectal mucosal lesions.
In the s and s, outbreaks of hepatitis B occurred in long-term care facilities e. Transmission occurs in households from persons who have immigrated from endemic areas and who have chronic HBV infection. Persons with either acute or chronic HBV infection should be considered infectious any time that HBsAg is present in the blood.
When symptoms are present in persons with acute HBV infection, HBsAg can be found in blood and body fluids for 1 to 2 months before and after the onset of symptoms. Direct, percutaneous inoculation of HBV by needles during injection-drug use is an important mode of transmission. Breaks in the skin without overt needle puncture, such as fresh, cutaneous scratches, abrasions, burns, or other lesions, may also serve as routes for entry. Exposures such as transfusion of blood or blood products, hemodialysis, use of meters and lancets for blood glucose monitoring, insulin pens, and needle-stick or other sharps injuries sustained by health care personnel HCP have all resulted in HBV transmission.
Outbreaks have been reported among patients in dialysis centers in many countries through failure to adhere to recommended infection control practices. Past outbreaks have been traced to tattoo parlors, acupuncturists, and barbers.
Hepatitis B became nationally notifiable as a distinct entity during the s after serologic tests to differentiate different types of hepatitis became widely available. New York Times. November 17, Hepatitis B vaccine: demonstration of efficacy in a controlled clinical trial in a high-risk population in the United States. N Engl J Med.
The prevention of hepatitis B with vaccine: report of the Centers for Disease Control multi-center efficacy trial among homosexual men. Ann Intern Med. Vertical transmission of hepatitis B antigen in Taiwan.
Hepatitis B immune globulin HBIG efficacy in the interruption of perinatal transmission of hepatitis B virus carrier state. Immunogenicity of hepatitis B virus vaccine in healthy Chinese neonates. J Infect Dis. Prevention of perinatally transmitted hepatitis B virus infections with hepatitis B immune globulin and hepatitis B vaccine. Postnatal infectivity of hepatitis B surface antigen-carrier mothers.
Incidence of hepatitis B virus infections in pre-school children in Taiwan. Incidence of hepatitis among students at a university in Taiwan.
Am J Epidemiol. Hepatocellular carcinoma and hepatitis B virus: a prospective study of 22, men in Taiwan. Access your subscriptions. Access through your institution. Add or change institution.
Free access to newly published articles. Purchase access. Rent article Rent this article from DeepDyve. Access to free article PDF downloads. Credit: CDC. In , the Recombivax HB vaccine for hepatitis B was approved for human use in several countries, the culmination of research started by William Rutter, Pablo Valenzuela and colleagues in on the cloning of hepatitis B virus HBV antigens.
It was the first vaccine to be produced using recombinant DNA technology and although it was only the third recombinant product to be approved for clinical use, it was also the most complex in forming nanoparticles that resemble patient-derived virus particles in both structure and immunogenicity.
HBsAg is encoded by gene S, which contains three in-frame start codons that enable production of HBsAg proteins of three lengths small, middle and large. The large HBsAg protein is the most abundant form found on the surface of infectious viral particles and is thought to have a crucial role in the binding of HBV to hepatocytes. HBsAg was first identified in by Baruch Blumberg as an antigen found in the blood of an Aboriginal Australian and it was later shown by Blumberg and others to be associated with HBV infection and to be part of the virus itself.
Given the failure since its discovery to cultivate HBV in vitro, the first commercial HBV vaccine Heptavax; licensed in was based on inactivated virus collected from the plasma of HBV-infected donors. Therefore, the use of recombinant DNA technology was an attractive option for development of a vaccine that solved both of these problems.
Targeting HBsAg was also attractive, given that it was encoded by a single gene and thought to be closely involved in interactions with host cells. In , William Rutter, who had been involved in research on recombinant insulin and growth hormone, and colleagues, including Pablo Valenzuela at the University of California, San Francisco, successfully cloned HBsAg into Escherichia coli expression vectors, demonstrating the possibility of using recombinant HBsAg as an HBV vaccine.
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