New vaccine against hepatitis B

1988/12/01 Agirre, Jabier - Medikua eta OEEko kidea Iturria: Elhuyar aldizkaria

• Osasuna

The germs reach the liver through the blood stream and it begins to swell until the abscess forms. If the process continues, the liver may fracture, dispersing the infection to other organs (peritoneum, pleura, lungs).

Viral hepatitis viral hepatitis

And within it, especially acute hepatitis.

Although it may appear at any age, especially in youth and childhood.

There are two main types, similar from the clinical point of view, but very different in terms of epidemiology.

Infective hepatitis

It suddenly appears as an epidemic (in schools, barracks, etc. ). The incubation period is short (2-6 weeks). The virus is introduced through liseria (by ingestion of contaminated food).

Serum hepatitis

It is taken by those who have been in contact with the blood or another liquid of people who carry virus in their blood (carriers): especially by inoculation (transfusions, syringes, etc. ). ). Longer incubation time (2-6 months).

They are considered to have been created by two different types of virus, A and B respectively. So we'll talk about hepatitis A and hepatitis B. Another virus is: Delta virus that needs the presence of the B virus to reproduce. This would produce hepatitis Delta.

Finally I will mention hepatitis no -B. This terminology is limited to showing our ignorance about the nature of viruses. The main risk of these hepatitis N-A no B is their ability to evolve to cronicity (50% of cases).

Chronic hepatitis Chronic hepatitis

The inflammatory hepatic process, which normally lasts more than a year, is called chronic. Along with the duration, we must take into account the modification of the hepatic structures associated with cirrhosis. Chronic hepatitis can be:

• Sustainable. The liver is not attacked too much. The forecast is good. In most cases, after a long process (even years), the lesions go back (some cure).
• Aggressive or aggressive. Evolution is more serious and in many cases the problem ends in cirrhosis.

The causes of chronic hepatitis are little known. Sometimes they can be a consequence of acute viral hepatitis. On other occasions, however, they are chronic from the beginning.

Chronic H. appear mostly in women (in young people). Its start is silent, tiredness (asthenia), loss of appetite, thinning and perhaps skin and mucous are yellowed. Symptoms can improve but also worsen.

The liver is swollen and the spleen also.

Laboratory results: addition of transaminases (especially aggressive), globulin G, GJA and bilirubin in blood (higher than normal).

Treatment of hepatitis

It depends on the type of hepatitis.

Usually it is recommended to rest (at least in bed, at the beginning), the passage of normal food but much freer than in other times, vitamins, hepatic protectors.

There is no special treatment in itself, except for immunostimulants (cyanidanol, e.g., has shown its usefulness in controlled trials).

But there are three rules:

• Never give corticoids.
• Perform analytical controls (prothrombin, TOG, TPG) and clinical weekly to control the evolution of hepatitis. Exceptionally, it may require hospitalization.
• Revisions made in the third and sixth months should check whether the process has been resolved or not. For this purpose, the transaminases, as well as the antigens of virus B (especially the HBs and HBe Antigens), will be determined so that the evolution to the cronicity does not go unnoticed.

Prevention of hepatitis

In the case of hepatitis A are general prophylactic measures (water control, purification and purification, and sanitary control of foods that are to be ingested in crude, such as seafood). There are other more specific preventive measures (especially immunization) by standard immunoglobulin, before or during the two weeks after exposure to the virus. This measure guarantees protection of 80-90%.

As a treatment, there is currently no effective drug against the virus A. Immunoglobulins do not affect the infection already reported. However, chronic forms have never been described in hepatitis A.

The case of hepatitis B is very different.

The virus itself is potentially oncogenic for humans and the B virus is directly involved in the etiopathogenesis of hepatic tumors. Hepatitis B, initially cirrhosis, can produce in many cases a primitive hepatic tumor.

And what is the reservoir or deposit of the virus? The man mainly. Since the infection is often asymptomatic (goes unnoticed), in many cases carriers are not detected and the infection occurs through blood or blood derivatives.

Here are the main transmission routes:

• YATROGEN. The risk is maximum for nurses, doctors, dentists and laboratory technicians. Hemodialysis units (patients and health personnel) have a special risk. For this reason, viral hepatitis has been declared a professional disease in all the aforementioned groups.
• SEXUAL. Apparently it is related to the number of bedspreads. This would explain the increased risk of homosexuals and/or prostitutes.
• INTRAFAMILIAR. The mechanisms of this transmission route are not yet known exactly.
• PREGNANCY. Mother-fetal transmission is mandatory when the mother is a chronic carrier of the virus or has been infected in the last trimester of pregnancy. The newly born infected becomes a chronic virus donor. No malformation has ever been described.

Worldwide, more than 280 million (according to the latest estimates) carry the B virus in their blood, or what is the same, chronic asymptomatic carriers. According to some WHO statistics, carriers of the B virus reach 20% of the total population in some endemic areas (and in certain places in Asia or sub-Saharan Africa the prevalence is around 80%).

As for health personnel, the different studies carried out in the hospital offer us worrying figures of prevalence and contamination: nurses in the emergency rooms (30%) staff of the blood banks (26%), laboratory technicians (24%), people who perform intravenous transfusions (22%), surgeons (11%) and nurses of compact responsibility (10%).

Before this panorama we have seen, what to do? It is clear that today prevention is the only way that can lead us to eradicate the disease. And here we must mention the vaccine against hepatitis B.

Currently we have two different types of vaccines. The vaccine extracted from plasma for years is in a position to be used, but on the one hand, its high manufacturing cost and on the other, doubts about its safety (generally unjustified) have considerably limited its use.

However, there are currently other genetically engineered vaccines on the market, “of a new generation”, but also those we could call “of a new generation”. Being constituted without human plasma, there is no theoretical risk of infections crossed by blood result. Genetic engineering, on the other hand, allows obtaining vaccines as often as desired and at a suitable price.

Genetic engineering has advanced a lot in very diverse fields. And about seven years ago attempts to get a new vaccine began, but all attempts to reproduce the gene extracted from the virus genome in a bacterium proved useless. Finally, a yeast (similar to barley yeast or bread) was used as a production tool to grow and reproduce the antigen again and again.

When a sufficient quantity has been produced, the antigen is extracted from the yeast cells and is cleaned or purified according to special techniques. The vaccine that has been put on sale among us, called ENGERIX-B, has been prepared by a particular commercial house or laboratory.

This vaccine is very effective, with a very high level of immunity (around 100% within one month after the three recommended doses). What is the administrative guideline? It is recommended to take three doses: the first one a month and the first one at six months. The vaccine obtained by genetic engineering is clinically safe, resistant (both for adults and children or newborns). However, this vaccine should not exclude other responsibilities or assistance to people who suffer or may have hepatitis.