Background/Purpose: Chikungunya virus (CHIKV) is a rapidly emerging arthritogenic mosquito-borne alphavirus that spread to the United States in 2014.  After an initial period of acute inflammatory arthritis, fever, and rash, patients with CHIKV infection often develop inflammatory arthritis that can persist for months to years.  Prior investigations were primarily focused on the infectious nature of the disease and patients from the Eastern Hemisphere.  Here, we describe the rheumatologic and immunologic features of a cohort of 10 American travelers who were almost simultaneously infected with CHIKV in Haiti, and compared them to newly diagnosed, untreated rheumatoid arthritis (RA) patients.

Methods: CHIKV infection was confirmed by the presence of anti-CHIKV IgG antibodies detected by enzyme-linked immunosorbant assay (ELISA). Features of disease were assessed by history, physical examination, and laboratory studies.  Peripheral blood mononuclear cells from RA and CHIKV-infected patients were phenotyped by mass spectometry (CyTOF).

Results: Eight of 10 CHIKV-infected individuals developed symmetric polyarthritis that persisted for a minimum of 6 weeks after the initial infection. Once the acute infectious symptoms resolved, the clinical features of CHIKV-related arthritis were indistinguishable from seronegative RA. CyTOF analysis of peripheral blood mononuclear cells suggested that both RA and CHIKV-infected patients had higher percentages of activated and effector CD4+ and CD8+ T-cells than healthy controls.  Spanning tree progression of density normalized events (SPADE) analysis of activation marker expression revealed a trend toward higher L-selectin expression in CD4+ T cells from RA patients compared to healthy controls and patients with CHIKV-associated arthritis.

Conclusion: Patients with persistent CHIKV arthritis exhibit T cell phenotypes similar to patients with untreated, active RA.  Given that CHIKV-related arthritis clinically mimics seronegative RA, there is a need for rheumatologists to consider CHIKV infection in the differential diagnosis of symmetric polyarthritis, especially since immunosuppression has the potential to exacerbate a virus-induced arthritic disease.  Rheumatologists should take a travel history and consider possible CHIKV exposure in patients with new-onset seronegative RA.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/immunological-phenotyping-of-a-cohort-of-american-travelers-with-chikungunya-viral-arthritis/