The detection of IL-7 and IL-15 is significantly interesting with regards to the immunopathology of CHIKF since CHIKV infection has been shown to induce rapidly developing and persisting arthralgia [6] . Here, 9 of the 10 patients manifested this pathology. IL-7 is known to have an important role in the development of rheumatoid arthritis [39] , while IL-15 has been associated with the development of joint inflammation [40] . It has been proposed that expansion of a particular IL15-induced NK cell subsets was responsible for this phenomenon [41] . The role of IL-15 and NK cells in the development of CHIKV arthralgia would definitively be worth investigating. We did not detect TNF-a in the plasma of the patients with acute CHIKV infection. This is surprising since this cytokine has been detected repeatedly in the blood of patients suffering from other arthritides such as rheumatoid arthritis and is known to be involved in the pathogenesis of these entities [42] . Thus, it is possible that CHIKV-induced arthralgia does not depend on TNF-a. Alternatively, TNF-a might be produced only locally. Analysis of synovial fluid or joint tissue immunohistochemistry would be necessary to provide important information on the role of TNF-a and other mediators.