The mosquito-transmitted chikungunya virus, which causes fever and joint pain which may resemble rheumatoid arthritis, was suspected in 3 million cases in the Americas as of 2016. A systematic review of six studies, which was published online recently in Arthritis Care & Research, evaluates the effectiveness of methotrexate in treating the virus.

Although the number of studies is limited, “taken together [they] demonstrate sufficient efficacy to justify interest in the treatment of chronic chikungunya arthritis with methotrexate,” write Robert Schoen, of Yale School of Medicine, and colleagues.

“The trials lacked rigorous study designs and used different treatment strategies and outcome measures,” they add, noting that their review “underscores the need for randomized prospective, placebo-controlled studies of methotrexate monotherapy in the treatment of chronic chikungunya arthritis.”

Writing in MedPage, Nancy Walsh notes that the chikungunya emerged in Tanzania in the 1950s, and it surfaced in the Americas in 2013. “The acute phase of the viral infection is characterized by fever, headache, rash, and polyarthralgia,” or pain in multiple joints, “lasting for about 10 days,” Walsh writes. “Then, in an estimated one-third to two-thirds of patients, musculoskeletal symptoms appear and can persist for months.”

Schoen and colleagues note that methotrexate is a “safe, effective, widely used drug” for treating inflammatory rheumatic diseases. Their review, they add, determines that no blinded, randomized clinical trials study the use of methotrexate for chronic chikungunya virus arthritis.

“Many patients with chikungunya fever will have resolution of joint symptoms without specific intervention or can be managed with symptomatic treatment such as NSAIDs. In some patients, however, arthritic symptoms may be more severe and last for months,” Schoen told MedPage.

“Available, limited evidence suggests that methotrexate may be an option, both in terms of efficacy and lack of reported toxicity,” he added. “But given the growing worldwide burden of chronic chikungunya arthritis, a careful, scientifically rigorous study of methotrexate in chronic chikungunya arthritis is needed.”