Hepatitis B: how it is contracted and incubation period

TheHBV virusbelongs to theHepadnaviridaefamily and is also the type species of the genusOrthohepadnavirus. It is a pathogen resistant to heating and freezing, although it is not possible to become infected by simple contact with surfaces where it is present. In fact, HBV is conveyed throughbloodandbody fluidssuch as semen and vaginal secretions. Therefore you can be infected if:

• You haveunprotected sexwith infected people;
• It comes into contact withthe bloodof infected individuals.

Direct contact with infected blood material is often attributable to:

• Use ofsyringes and / or medical devicesnot adequately sterilized;
• Transfusion of infected blood(frequent in countries where correct analyzes are not performed due to the fragility of the health system);
• Piercings or tattoos carried out without respecting the necessary precautions;
• Sharing of personal care tools (razors, tweezers, scissors etc.);

This form of hepatitis can also betransmitted vertically, i.e. from mother to foetus. For this reason it is good that pregnant women (or who would like to carry one out) consider the possibility of getting vaccinated against this disease.

Theincubation period ofhepatitis B can be particularly long and even reach 180 days, although in most cases the estimated time varies from 45 to 90 days.

What are the differences with other forms of hepatitis?

Hepatitis B differs from forms A and C in numerous respects. The following are the main differences:

• hepatitis Ais not sexually transmitted (except for oral-practices), while hepatitis B can be transmitted as a result of contact with semen or vaginal secretions of infected individuals;
• unlike hepatitis A, hepatitis B can also be transmitted through the blood;
• unlike hepatitis A, hepatitis B canbecome chronic in adults (in about 10% of cases) and carry the risk of developing livercirrhosisandliver cancer;
• a hepatitis B patient has about a 90%chance of curingthe disease, while in the case of hepatitis A the probability of recovery is 99% and for form C it does not exceed 20%;
• the probability of developing the chronic form ofhepatitis Bis much lower than in the C form (which becomes chronic in about 80-85% of cases);
• mortalityrelated to hepatitis B is higher than in form A but lower than form C.

The main symptoms of hepatitis B and the course of the disease

Thefirst symptoms of hepatitis Busually occur no earlier than 90 days after infection, i.e. the incubation period of the HBV virus. In some cases, however, they may occur even after only 45 days. Keep in mind that the disease can also have an asymptomatic course, but this aspect does not make it less contagious. In fact, anyone infected with the hepatitis B virus can transmit it, even in the absence of symptoms and during the incubation period.

Themost common symptomsof this form of hepatitis are:

• Abdominal pain;
• High fever;
• Nausea and vomiting;
• Loss of appetite and fatigue;
• Joint pain;

If liver damage has already occurred, jaundice appears, i.e. the yellow coloration of skin and eyes caused by excessbilirubin (pigment obtained from the destruction of red blood cells) in the body. The accumulation of this pigment also causes thedark colorationof the urine and thevery light staining of the patient’s feces.

In 90% of cases complete healing occurs in no more than 6 months. The cured subject will be immunized for life against HBV. In about 1% of cases, a fulminant form may occur that requires immediate liver transplantation and has a mortality of 90% of cases.

What does the chronic form of hepatitis B involve?

If HBV infection persists for more than 6 months, it is calledchronic hepatitis B. It is a form that mainly affects patients under the age of 5 years (in some cases an incidence close to 90% has been observed), while in adults the chances of developing the chronic form areequal to 10%.

It should be noted that the development of the chronic form of hepatitis B does not necessarily imply the impossibility of curing the disease. In fact, hepatitis is chronic when the immune system fails to completely eliminate the virus before 6 months and is divided into:

• Persistent: if HBV continues to be present in the body but is unable to cause serious liver damage. Usually the disease tends to heal, albeit with considerable delay, or the patient remains a chronic carrier but does not develop liver complications;
• Aggressive: occurs when liver damage worsens in intensity over time. You may experienceliver cirrhosisand / orhepatocarcinoma (the most common and aggressive form of liver cancer);

Mortalityamong those affected by chronic hepatitis B is estimated at around 15-25%.

Treatment and prevention of hepatitis B

There is no specific treatment for the acute form of the disease, which usually heals spontaneously. However, it is possible to administer specific antibodies against the pathogen (anti-HBV immunoglobulins) to the patient within the first 48 hours of the presumed infection. The use of immunoglobulins also helps prevent infection in newborns born to motherswith acute or chronic hepatitis. If the administration takes place within the first 12 hours of life, the risk of contracting this disease drops by90% (source).

There are no drugs that can completely eliminate the hepatitis B virus in case ofchronic disease. However, there are several therapies that block its replication in order to prevent liver damage. Among the most used drugs are:

• Interferons: these are proteins commonly produced by the cells of the immune system in response to the presence of pathogens or neoplastic cells. Those commonly used in chronic hepatitis B are interferon α-2a, interferon α-2b, α-natural interferon andpeginterferon α-2a. The latter requires only one injection per week, while the others need three.
• Antivirals: they can be taken individually or in combination with interferons depending on the opinion of the attending physician. They serve to prevent thereverse transcriptasemechanism of the HBV virus. Among the most used drugs are Adefovir,LamivudineandTenofovir (also used forHIV treatments). If the patients being treated havekidney disease, a dose reduction can be chosen.

In addition, those who have developed the disease in a chronic form must follow a diet low in saturated fats, fried foods, alcoholic beverages (total elimination is recommended) and the intake of drugs that could cause liver damage.

How to prevent hepatitis B infection?

Speaking of prevention, the following behaviors can help prevent HBV infection:

• Use of condoms during penetrative sexual intercourse;
• Use of protective equipment during oral sexual intercourse;
• Avoid contact with blood material of unknown origin;
• Do not come into contact with potentially infected syringes or utensils;
• Carefully sterilize medical environments;
• Do not use razors, tweezers and other personal care items belonging to strangers;
• Use disposable needles for tattoos.

As for hepatitis A, also for form B there is avaccinecapable of protecting against contagion. Following vaccination, the percentage of protection from contagion is approximately 95%, with an estimated protection between 12 and 25 years depending on the immune response of the organism of the vaccinated individual. In Italythe HBV vaccine has been mandatory since 1991. Individuals who should give more consideration to hepatitis B vaccination in countries where vaccination is not mandatory are:

• Health personnel;
• Immunosuppressed subjects or cancer patients;
• People with numerous sexual partners;
• Subjects who live with chronically ill people;
• Anyone who risks coming into contact with blood material.