(BMJ)—A 58-yo nurse who recently traveled to Kenya presented w/ fever and excruciatingly painful swelling of the small joints of the hands and wrists. Exam: swollen finger joints. Labs: increased CRP; increased plasma viscosity; neg for autoantibodies, HIV, malaria, syphilis. What is the dx?
Gonococcemia
Bussuquara fever
Rheumatoid arthritis
West Nile virus infection
Chikungunya
You are correct. Rising antibody titers to chikungunya virus confirmed the dx. Chikungunya was once considered a tropical illness, but now has a far wider geographical spread. It mirrors West Nile virus and has become endemic in the U.S. Clinicians in the Western Hemisphere should be aware that chikungunya virus can mimic RA. Prompt recognition avoids unnecessary use of immunosuppressive drugs.

BMJ 2017;356:j250