Molecular Epidemiology of Hepatitis B in Cayenne General Hospital, French Guiana

Human demography and migrations play a crucial role in the phylogeography of viral populations. Hepatitis B viruses are characterized by a high genetic diversity which results from the fact that this virus uses a reverse transcriptase during its replicative cycle, which induces errors and therefore variation. A dozen genotypes have so far been described and are subdivided into sub-genotypes which have a distinct ethnogeographic distribution. Genotypes A and D are ubiquitous and represent the most common genotypes in Europe; genotypes B and C are very common in Asia and Oceania, genotype E in Central Africa and West Africa, genotypes H and F in Latin America and Alaska, and Genotype I in Southeast Asia. The populations originating from these different continents are all represented in Guyana and it is therefore interesting to understand what are the chains of transmission and the phylodynamic aspects of the epidemic in French Guiana. In addition, the different genotypes have variable clinical consequences, and this in different ways depending on the ethnicity of the host. Thus, in Mexico, the F and H genotypes appear to be rather benign in the Amerindians among whom they have circulated for a long time. On the other hand, genotypes F, A and D are of rather severe evolution in Mexicans of Caucasian origin, thus suggesting that the immunogenetic factors of the host are important determinants of the pathogenic power of the viruses (Roman and al WJG 2014).

Some pre-core mutations leave the virus with the capacity to replicate. The absence of the HBe antigen deprives the immune system of an important target and the virus can therefore continue to replicate. These pre-core mutations are associated with the HBe Ag negative phenotype (7 to 30% of patients) which is associated with a more severe course of chronic hepatitis. These mutations are of increasing and high frequency (Funk ML, and al 2001).

Addiction to crack cocaine is widespread in French Guiana and appears to be one of the drivers of the epidemic. The pipes used to smoke crack cause burns on the lips and when sharing the pipe could contribute to increasing the risk of transmission (Fischer and al 2008). Risky sexual behavior is associated with the use of crack cocaine, suggesting that there may be specific chains of transmission around crack users.

Primary objective Identify the factors associated with different genotypes (age, sex, country of birth, sexual orientation, sexual risk taking, notion of IV drug addiction, crack ...) in order to identify specific chains of transmission in French Guiana.

Secondary objectives