11/14/2023 0 Comments Hbv transmissionNew viral DNA genomes are enveloped and leave the cell as progeny virions.Viral mRNA and reverse transcriptase are packaged into a capsid, where viral mRNA is then reverse-transcribed into viral rcDNA.The viral mRNA leaves the nucleus and is translated into HBV core proteins and new reverse transcriptase in the cytoplasm.The cccDNA is then transcribed into viral mRNA by host RNA polymerase.The rcDNA is converted to covalently closed circular DNA ( cccDNA ) primarily by host enzymes in a process that is not entirely understood.After entering the host cell's nucleus, reverse transcriptase completes the positive strand of the virus 's partially double-stranded relaxed circular DNA ( rcDNA ).HBV carries a DNA polymerase with both DNA and RNA-dependent functions, also known as reverse transcriptase (RT). Health care personnel (e.g., needlestick injury ).Current or previously incarcerated individuals.Household, sexual, or needle-sharing contacts of individuals with HBV.History of sexually transmitted infections or multiple sexual partners.Injection drug use (current or previous).Unvaccinated children born to parents from countries with high HBV prevalence ( ≥ 8%).Individuals born in countries with medium-to-high HBV prevalence ( ≥ 2% ).Risk factors for HBV infection and groups at risk Travelers to regions where HBV is endemic.Hepatitis C virus ( HCV) and HIV-positive individuals.Vertical transmission ( mother-to-child transmission).Blood transfusions or organ transplants.Contaminated needles or instruments (including those for procedures like body piercings, tattoos, and acupuncture ) that come into contact with the patient's blood.Sexual : transmitted when bodily fluids come in contact with broken skin or mucous membranes (mouth, genitals, or rectum ).See “ General virology” for more information on viral structure.įrequency and patterns of transmission vary worldwide.Circular, partially double-stranded DNA virus.Other preventive measures include postexposure prophylaxis for newborns of mothers with hepatitis B and unvaccinated individuals with recent exposure to HBV. Prophylactic immunization with a recombinant vaccine is recommended for all age groups. For chronic active hepatitis B, nucleoside or nucleotide analogs (e.g., tenofovir) are the preferred agents for reducing viral replication and infectivity. In patients with fulminant hepatitis, liver transplantation may be necessary. Treatment of acute hepatitis B consists of supportive measures. CHB with persistent liver inflammation is characterized by detectable HBsAg and elevated HBV DNA and ALT. A detectable serum anti‑HBs (indicating seroconversion) is a sign of recovery or successful immunization. Serologic testing initially includes measurement of hepatitis B surface antigen ( HBsAg), hepatitis B surface antibody ( anti-HBs), and hepatitis B core antibody (anti-HBc). Individuals with CHB may be asymptomatic carriers or develop ongoing hepatic inflammation with an increased risk of cirrhosis and hepatocellular carcinoma. However, 5% of adult patients and 90% of infants infected perinatally develop chronic hepatitis B (CHB). After an incubation period of 1–6 months, most patients develop asymptomatic or mild inflammation of the liver, which usually resolves spontaneously within a few weeks or months. It occurs worldwide and is transmitted sexually, parenterally, or vertically. Hepatitis B is a viral infection caused by the hepatitis B virus ( HBV).
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