Hepatitis B virus

hepatitis b virus

What is the hepatitis B virus?

Hepatitis B is a small, encapsulated virus within the Hepadnaviridae family. The virus was discovered in 1970. It has a genome consisting of a circular, partially double-stranded DNA. Hepatitis B is one of the most commonly occurring contagious diseases worldwide. Two billion people have already been infected with the hepatitis B virus (HBV), and 240 million people suffer from chronic HBV infection. While hepatitis B occurs worldwide, its prevalence is highest in sub-Saharan Africa and East Asia. In these regions, five to ten percent of adults are chronically infected with HBV. Although an effective vaccine has been available since the early 1980s, a great number of people become infected with hepatitis B every year. However, the trend is declining. According to the World Health Organization (WHO), there are 780,000 deaths per year caused by HBV infection.

How is hepatitis B transmitted?

There are many different ways of transmitting the hepatitis B virus. It can be passed on through blood as well as through body fluids such as saliva, tear fluid, sperm and vaginal fluid. Unprotected sexual intercourse poses a particularly high risk of infection. Similarly, the risk is very high for people who inject drugs and share syringes and cannulas with HBV patients. In addition, an unhygienic blood glucose check, tattooing and piercing, as well as other small injuries that involve body fluid transfers with infected persons increase the risk of transferring the virus. A mother can also transmit the virus to the infant during birth – resulting in a lifelong, chronic HBV infection of the child.

How does the disease manifest itself?

An infection with the virus can manifest itself in many different ways. Depending on the patient’s immune system, the severity of the symptoms can vary. In about 30 per cent of affected adults, HBV infection leads to icteric hepatitis, in other words, hepatitis with jaundice. However, in another 30 per cent of cases, patients do not develop jaundice. In other cases, the infection progresses with no symptoms at all. In 0.5-1 per cent of cases, severe hepatitis with acute liver failure may occur.

When hepatitis occurs with symptoms, the early phase (prodromal stage) begins with symptoms including loss of appetite, joint pain, malaise, nausea, vomiting and fever. If icteric hepatitis occurs, it usually starts three to ten days after the first symptoms have set in. The icteric phase reaches its peak after one to two weeks. This phase is characterized by jaundice and dark-coloured urine. Symptoms will fade after two to four weeks. In children, reddish papules may appear, mainly on the face. In 90 per cent of hepatitis B cases, the disease heals completely. Most infected patients are immune for life. However, in ten per cent of patients, a chronic infection may occur. This is the case when a surface protein in the viral envelope of the HBV can be detected in the patient’s blood serum for more than six months. Often, the acute disease had not been previously diagnosed in such patients. The probability of developing chronic hepatitis B also increases in infants who were infected at birth (90 per cent), in children under the age of three or in people with a weakened immune system (30-90 per cent). If chronic hepatitis B occurs, liver cirrhosis or hepatocellular carcinoma may develop over time. Anyone who already has liver cirrhosis also has a significantly increased risk of developing liver cell carcinoma (two to seven per cent).

Significance for infections in hospitals and in the outpatient sector

Basic hygiene measures must be adhered to in hospitals and outpatient departments. All activities involving contact with body fluids also require wearing of protective gloves. If there is a risk of droplet transmission, protective gowns, mouth and nose protection and safety glasses must be worn as well. In Germany, Switzerland and Austria, when hepatitis B is detected, it has to be reported.

Survival time of pathogens on inanimate surfaces:

At least one week.

Disinfectant effectiveness for prevention:

The required spectrum of activity against the hepatitis B virus is: limited virucidal.

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