What is it?
Hepatitis B is an infectious disease caused by the hepatitis B virus. It can cause both acute and chronic infections, and it affects the liver. Most people have no symptoms when they first become infected, but some experience things like vomiting, a yellowish skin, tiredness, and stomach pain. The vast majority of infants infected go on to develop chronic hepatitis B, but the risk of this happening decreases sharply when the child has gained a couple of years of age. Most chronic hepatitis B cases don’t involve symptoms, but 15-25% of those affected eventually die of complications like liver cancer and cirrhosis.
A third of the world’s population is estimated to have been infected at some point, and 240-350 million people suffer from the chronic disease. Over 750 000 people die because of hepatitis B each year. The disease is most common in sub-Saharan Africa and East Asia – in these areas 5-10% of adults have the chronic disease.
What causes it?
Hepatitis B is caused by the hepatitis B virus. It is transmitted through contact with infected blood or other body fluids containing traces of blood. This can occur during sexual contact and through blood transfusions and the use of contaminated drug needles.
What happens during it?
Viruses are not living things. They are essentially protein shells containing genetic information, and they reproduce through invading a host cell and making it produce new viruses along their instructions. The cell normally dies after a sufficient amount of viruses has been produced, and the viruses go on to infect other cells. The hepatitis B virus is specialized in reproducing inside, and later killing, liver cells.
When viruses invade a cell, their DNA becomes integrated with the cell’s own DNA. This can sometimes have disastrous consequences. Cancer happens when the genes that regulate cell growth and communication become mutated, and if the virus DNA happens to be inserted in the middle of this kind of gene, the gene might stop working normally and the cell might start dividing uncontrollably. This is one of the theories attempting to explain why liver cancer is so prevalent among hepatitis B patients.
Another possible cause of liver cancer is the cirrhosis seen in almost all patients with chronic hepatitis B. As a result of the infection, the liver cells start to die, and they are replaced by scar tissue. It is thought that in the process of new cell generation there might be a higher risk of mutations occurring and thus a higher risk of cancer.
How can it be treated?
There is an effective vaccine against hepatitis B, and it is recommended that it’s given on the day of birth. It is very rare for an acute infection to require treatment. Chronic infections are treated with antiviral medications – although they aren’t able to clear the virus out of the body entirely, they are able to make it stop replicating.
Sources: en.wikipedia.org/wiki/Hepatitis_B, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3047495/, http://emedicine.medscape.com/article/177632-overview?pa=53aTLjPGrNaNRDajKxvzkHdGykeLpy71JSse%2FqGCzGoqj5acuRTy5q2W2ag%2Fxsoi43mU9jD%2B1DtnxY47OmyybA%3D%3D#a3