Genetic Factors and Immunological Determinism of Persistent Consequences of Chikungunya
Condition: Chikungunya Fever
MeSH terms: Chikungunya Fever; Fever
Study type: Observational

Summary: 
      Chikungunya virus (CHIKV) infection has become a threat to public health worldwide. Reunion
      Island, due to the 2005-2006 epidemic, has acquired unique expertise and remains at the
      forefront of global research on this disease. The idea of genetic determinism of the clinical
      expression of infectious diseases has been supported by many epidemiological arguments over
      the past fifty years. The identification of genetic variants, associated with a disease,
      often allows a better understanding of the molecular mechanisms involved with consequent
      significant benefits such as the development of specific biomarkers for new preventive
      (vaccination) and / or therapeutic (drug design) approaches. In the absence of
      well-documented hypotheses about the genes potentially involved in the occurrence or
      evolution of a disease, genome-wide association studies (GWAS), whole genome, of nucleotide
      polymorphisms (SNPs) and the principle of linkage disequilibrium, under the commonly accepted
      hypothesis that the expression of a common disease is based on a small number of alleles
      commonly found in the population (frequency of minor allele greater than 1-5%), have become a
      method of choice, free of hypothesis, to specify the part of heritability of a complex
      disease and to identify its genetic determinants. Several epidemiological arguments support a
      significant proportion of genetic determinism in the explanation of the evolutionary pattern
      of Chikungunya, whose proportion of chronic forms can reach 40-60% in population-based
      studies conducted in the two years following an epidemic:

        -  There are few risk factors associated with chronic forms and these appear to be unclear
           (age, comorbidities with several elements of the metabolic syndrome) or inconsistent
           (immune burden) in population studies;

        -  The incidence of severe or atypical forms is rare in the order of 1% of infections;

        -  In contrast to the acute phase (J1-J21) for which there seems to be a role of the viral
           load intensity and a consensual pro-inflammatory immune signature according to a recent
           meta-analysis]; The role of the intensity of the viral load in the pathogenesis of
           chronic arthralgia (> J90) and their immune signature remain to be determined, the
           latter being rather nonspecific, according to studies conducted in Reunion, Italy or
           Singapore.

      These elements justify the interest of a GWAS in the Chikungunya to identify new avenues and
      mechanistic hypotheses likely to explain the chronic arthralgia characteristic of the
      disease.
    


Intervention name(s): Quality of life survey; Saliva collection; Blood collection
Intervention type(s): Other; Genetic; Genetic
Intervention description(s): Administration of scales: SF-12v2, EQ-5D, QCD, DN4, EIMIR, MFIS-5 et EHAD; Collection of 20 ml of saliva with a kit of saliva collection; Collection of 20 ml of blood with kit of blood collection
Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Subject with a serological status known for Chikungunya virus for the period between March
        1st, 2005 and December 31st, 2006 (epidemic period in reunion Island).
      
Biospecimen description: 
      Saliva and blood collection for genetical analysis (GWAS)