Hepatitis B is an infection caused by the hepatitis B virus (Pic. 1) which inflames the liver. Hepatitis B is one of the most serious types of hepatitis. The virus can cause either acute (short-lived) or chronic (long term) liver disease. The disease can affect babies, children and adults.
The natural history of hepatitis B is complex and is influenced by many factors, including age at infection, viral factors (HBV genotype, viral mutations, level of HBV replication), host factors (gender, age, and immune status), and exogenous factors such as concurrent infection with other hepatotropic viruses (viruses, which damage liver tissue) or alcohol.
Many people have no symptoms during the initial infection. Some develop a rapid onset of sickness with vomiting, yellowish skin (Pic. 2), tiredness, dark urine and abdominal pain. Often these symptoms last a few weeks and rarely does the initial infection result in death. It may take 30 to 180 days for symptoms to begin.
Most of those with chronic disease have no symptoms; however, cirrhosis (a condition in which the liver does not function properly due to long-term damage) and liver cancer may eventually develop (Pic. 3). These complications result in the death of 15 to 25% of those with chronic disease.
The infection can be diagnosed 30 to 60 days after exposure. Diagnosis is typically by testing the blood for parts of the virus and for antibodies against the virus.
As hepatitis B is spread through blood-to-blood contact with an infected person, it is important to practice safe sex and take care not to exchange body fluids during sex. People with more than one sexual partner (or whose partner has more than one sexual partner) are at risk of getting an STI like hepatitis B. Always using condoms and a water-based lubricant when have vaginal or anal sex is the best way to reduce a risk of hepatitis B. The hepatitis B viruses cannot be spread by holding hands, sharing eating utensils, kissing, hugging, coughing, sneezing, or breastfeeding.
Vaccination is recommended by the World Health Organization in the first day of life if possible. Two or three more doses are required at a later time for full effect. This vaccine works about 95% of the time.
In those who develop chronic disease antiviral medication such as tenofovir or interferon may be useful; however, these drugs are expensive. Liver transplantation is sometimes used for cirrhosis.
Symptoms of acute infection with hepatitis B virus
Acute infection with hepatitis B virus is associated with acute viral hepatitis – an illness that begins with general ill-health, loss of appetite, nausea, vomiting, body aches, mild fever, and dark urine, and then progresses to development of jaundice. It has been noted that itchy skin has been an indication as a possible symptom of all hepatitis virus types. The illness lasts for a few weeks and then gradually improves in most affected people. A few people may have more severe liver disease (fulminant hepatic failure), and may die as a result. The infection may be entirely asymptomatic and may go unrecognized.
Symptoms of chronic infection with hepatitis B virus
Chronic infection with hepatitis B virus either may be asymptomatic or may be associated with a chronic inflammation of the liver (chronic hepatitis), leading to cirrhosis over a period of several years. This type of infection dramatically increases the incidence of hepatocellular carcinoma (Pic. 1; liver cancer). Across Europe hepatitis B and C cause approximately 50% of hepatocellular carcinomas.
Symtoms outside of the liver
Symptoms outside of the liver are present in 1–10% of HBV-infected people and include polyarteritis nodosa (a systemic inflammation of vessels), membranous glomerulonephritis (a slowly progressive disease of the kidney), and papular acrodermatitis of childhood (a common skin condition in children which causes itchy, red or purple blisters, swollen and sore lymph nodes, and a bloated abdomen).
Infection may lead to liver damage that results in acute or chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma (HCC). Enhanced viral replication leading to a vigorous and extensive immune response may lead to massive liver injury resulting spontaneously into fulminant hepatic failure.
Chronic carriers are encouraged to avoid consuming alcohol as it increases their risk for cirrhosis and liver cancer.
There is a reliable and safe vaccine available to prevent the spread of hepatitis B.
Hepatitis B virus is capable of penetration of blood-testis barrier and also integrate into their genome (the genetic material of an organism). HBV can induce chromosomal aberrations (a missing, extra, or irregular portion of chromosomal DNA). This could lead to hereditary defects in male germinal cells and irregularities in spermatogenesis (sperm development).
In every body cell include sperms, there are smaller parts called organelas. One of them is mitochondry which is responsible for energy of sperm. HBV protein can change the potencial on mitochondrial membrane which leads to loss of energy. Patients infected with HBV have decreased motility of sperms. There is lower possibility of pregnancy in natural way.
Persons with self-limiting infection clear the infection spontaneously within weeks to months.
Children are less likely than adults to clear the infection. More than 95% of people who become infected as adults or older children will stage a full recovery and develop protective immunity to the virus. However, this drops to 30% for younger children, and only 5% of newborns that acquire the infection from their mother at birth will clear the infection. This population has a 40% lifetime risk of death from cirrhosis or hepatocellular carcinoma. Of those infected between the age of one to six, 70% will clear the infection.
Hepatitis B virus DNA persists in the body after infection, and in some people the disease recurs. Although rare, reactivation is seen most often following alcohol or drug use, or in people with impaired immunity. Approximately 50% of overt carriers experience acute reactivation.