Hepatitis B is an infectious inflammatory
illness of the liver caused by the hepatitis B virus (HBV) that affects
hominoidea, including humans.
Originally known as “serum hepatitis”, the disease has caused epidemics in parts of Asia and Africa, and it is endemic inChina.
About a third of the world population has
been infected at one point in their lives,[3] including 350 million who
are chronic carriers.
The virus is transmitted by exposure to
infectious blood or body fluids such as semen and vaginal fluids, while
viral DNA has been detected in the saliva, tears, and urine of chronic
carriers.
Perinatal infection is a major route of
infection in endemic (mainly developing) countries. Other risk factors
for developing HBV infection include working in a healthcare setting,
transfusions, and dialysis, acupuncture, tattooing, extended overseas
travel and residence in an institution.
However, Hepatitis B viruses cannot be
spread by holding hands, sharing eating utensils or drinking glasses,
kissing, hugging, coughing, sneezing, or breastfeeding.
The acute illness causes liver
inflammation, vomiting, jaundice and, rarely, death. Chronic hepatitis B
may eventually cause cirrhosis and liver cancer—a disease with poor
response to all but a few current therapies. The infection is
preventable by vaccination.
Hepatitis B virus is an hepadnavirus—hepa
from hepatotropic (attracted to the liver) and dna because it is a DNA
virus—and it has a circular genome of partially double-stranded DNA.
The viruses replicate through an RNA intermediate form by reverse transcription, which practice relates them to retroviruses.
Although replication takes place in the
liver, the virus spreads to the blood where viral proteins and
antibodies against them are found in infected people.
