ZOOM SUR ...

Ces dernières années, le traitement de l’hépatite C a beaucoup évolué permettant la guérison complète des patients dans la majorité des cas. Par ailleurs, en France, on estime que l’hépatite B chronique touche environ 0,65 % des adultes âgés de 18 à 80 ans, soit environ 280 000 personnes. Nous trouvions intéressant de faire un point sur les hépatites virales en 2018. Pour cela nous nous sommes adressés à notre directeur d’UMR, le professeur Michael Kann, spécialiste des hépatites.

Professeur Michael Kann, pouvez-vous svp nous faire un point sur la prise en charge et le traitement des patients souffrant d’hépatite B ou C aujourd’hui en France?

The situation for hepatitis C – before the introduction of the lastest antivirals – and hepatitis B is similar: acute infections, which are mostly asymptomatic, are not the real problem but the chronic infections, also showing no or few symptoms. However, after years of infection, a significant part of the infected individuals develop liver fibrosis, cirrhosis and liver cancer; the latter two arriving in 20 – 30% of chronically infected. The low rate of symptomatic infection cause that infection is mainly discovered upon screening or when symptoms of liver dysfunction have already developed.

It has to be noted that hepatitis B-infected can exhibit extremely high viral loads as 10⁹ – 10¹⁰/mL, which are several orders of magnitude above those observed for HCV and HIV. Moreover, the virus is more infectious then HCV and HIV so that even invisible traces of blood can cause infection.

In contrast to hepatitis C, there is currently no cure for hepatitis B. The molecules, which are nowadays used, attack the viral polymerase suppressing the production of new viruses. They are not able to target the viral DNA inside the hepatocytes, which is similar to HIV, and most patients have to be treated life-long. The advantage of HBV is that there is no resistance development against the mostly used drug Tenofovir. Despite of a good tolerance to this drug not everybody is treated: treatment recommendations concern patients with elevated viral load or those having symptoms with the major goal to improve survival and quality of life by preventing disease progression including cancer development. An additional aim is to prevent mother-to-child infections, which occur during birth. Considering the latest results showing that it takes several years of treatment to reduce the liver cancer risk, the recommendations became less a restrictive during the last years.

Qu’en est-il du reste du monde ?

Much more difficult! In fact there are around 260 million mostly chronically HBV infected people on earth. The virus prevalence in sub-Saharan Africa and South-East Asia reaches up to 20% and the antibody prevalence 80 – 95%. In particular in sub-Saharan Africa the situation is difficult as even hospital patients are just tested for HIV even South Africa, which is the richest of those countries. In China, the situation changes as all newborns – at least in Cities – become vaccinated. In Taiwan, where such a vaccination program is implemented for more than 20 years, not only cirrhosis but also liver cancer frequency dramatically dropped. Of note: at least in Mainland China it is a stigma, being HBV infected and students have been expelled from university for their infection.

Just one word about vaccination: the vaccine is very well tolerated but success has to be controlled as not everybody reacts sufficiently well. The link between hepatitis B vaccination and multiple sclerosis is an exclusively French problem and – to my knowledge – based on the disastrous decision of Bernard Kouchner in 1998 to stop the running vaccination campaign in the colleges, arguing that “one cannot exclude that the vaccination cause or may facilitate the development of demyelinising diseases of the central nervous system”. Of course, the careful wording “cannot exclude” is not necessarily well transported by the media. The consequence: in 2009, the HBV vaccination rate of 1-year-old babies was 27% in France but more than 90% in nearly all other EU countries!

L’OMS s’est fixé pour objectif d’éliminer les hépatites en 2030. Pouvez-vous nous décrire les différents critères pris en compte et nous donner votre point de vue sur leur stratégie et leur ambition ?

This is a truely ambitious aim. Modeling showed that the current treatment has to be given for several decades to eliminate infection. Vaccination does not help the already uninfected individuals, which will mostly be still alive in 2030. Thus, new molecules are needed but no clear treatment strategy is obvious. Moreover, it is unclear if natural clearance of acute hepatitis B really eliminates all viruses. In up to 20% of these individuals severe immune depression reactivates the infection despite of the fact that they showed all signs of a viral elimination. This means that the virus is still present on a very low level but that the immune system controls infection. As discussed in the frame work of the ANRS program “HBV cure”, a treatment leading to a “host controlled and undetectable infection” would be already a tremendous success.