Hepatitis B Virus

Introduction

Hepatitis B (HBV) is one of six viruses which cause hepatitis, an inflammation of the liver. Formerly known as post-transfusion or serum hepatitis, HBV is transmitted through infected blood and other body fluids, rather than by food or casual contact. Infection can cause acute disease, with symptoms including nausea, malaise, diarrhea, joint pain, and abdominal pain. In some cases, HBV infection progresses to chronic disease, damaging the liver and causing cirrhosis and liver cancer, which may be fatal. In countries where HBV infection is common, liver cancer rates are relatively high. Since the advent of screening of blood for HBV in developed countries, rates of infection have gone down, although people are still at risk through injecting drug use and sexual contact. An effective vaccine helps to protect babies from mother-to-child transmission and to stop those who work with blood from being infected with HBV through accidental exposure.

Discussion

Disease of the liver, characterized by jaundice (a sallow, yellow skin tone), fever, weakness, loss of appetite, and abdominal and muscle pains. Two principal types have been identified. Hepatitis A (also known as infectious hepatitis) is caused by a filterable virus called HAV. It is carried primarily by contaminated water supplies and food, although it may also be spread by injection by contaminated needles. Hepatitis B (serum hepatitis), caused by a closely related virus called HBV, is spread primarily through injection by contaminated needles, although mosquitoes may also occasionally carry it. Both types lead to death in approximately 10% of all cases. Those who survive may suffer permanent liver damage. The acute phase in both types lasts approximately two weeks, followed by a convalescence of roughly six months. Incubation time: HAV, 2-6 weeks; HBV, 6 weeks-6 months. (Bertoletti, 561-69)

Hepatitis B Virus

A virus is a submicroscopic particle consisting of a nucleic acid surrounded by a protein coat and capable of infecting animal, plant, or bacterial cells. Viruses do not contain all of the components needed to live as an independent organism so they must infect living cells to propagate new virus particles. For this reason, viruses are referred to as obligate intracellular parasites. (Freedman, 23)

Viruses that infect animal cells often infect more than one species. For example, various seasonal influenza viruses have the ability to infect humans as well as swine, birds, and other animals. Animal viruses do not cross-infect plant or bacterial cells, however. Viruses specific for plants do not infect animals, and viruses that infect bacteria, called bacteriophages, do not infect either animals or plants.

Hepatitis B Virus

Virus

Form of Genome

Transmission

Prevention

hepatitis B

DNA

blood, body secretions, sexual, contaminated needles

HBV vaccine

Hepatitis B infection is sometimes referred to as serum hepatitis, as it occurs only by direct inoculation or inoculation through the body's mucous membranes. Mucous membranes occur at the body's passages or cavities that are exposed to the air: nasal passages, mouth, and urogenital tract. Humans serve as the main carrier in infecting other people. Intravenous drug users also have a higher-than-normal incidence of HBV infection. The virus is not spread in ...