Between 5% and 20% of individuals with chikungunya infection develop chronic arthritis that is indistinguishable from rheumatoid arthritis (RA). Management typically follows the same approach used when no viral cause is identified, according to Licia Maria Henrique da Mota, MD, of the University Hospital of Brasília, Brasília, Brazil, and the scientific director of the Brazilian Society of Rheumatology. She highlighted the issue at the 58th Argentine Congress of Rheumatology, held from October 8 to 11, 2025, in San Miguel de Tucumán, Argentina.

Speaking with Medscape’s Spanish edition, she said, “You can call it rheumatoid arthritis because it will meet the criteria for this condition. Even the characteristic autoantibodies of the disease are positive in these patients. And the therapeutic approach can be exactly the same as for rheumatoid arthritis: You must wait for the evolution and treat according to the intensity of symptoms.”

She added that clinicians may label conditions differently, “but the disease does not know what you call it, and the body is suffering. That is why it needs treatment, and the treatment is remarkably similar.”

Chikungunya, first described in Tanzania in 1952, has expanded rapidly since 2004 and is now detected in more than 110 countries across Asia, Africa, and the Americas, according to the World Health Organization. In August 2025, the Pan American Health Organization issued an epidemiological alert for outbreaks in Bolivia, Brazil, and Paraguay, citing 212,029 suspected cases and 110 deaths across 14 countries. Projections indicate that the number of cases will continue to increase.

Similarities and Differences

Moderate-to-severe pain and inflammation in the joints of the feet and hands frequently define chikungunya infection compared with other arboviral infections transmitted by Aedes mosquitoes, although joint symptoms also occur in Zika and dengue infections.

“Chikungunya is the only one in which the joint manifestations become chronic, and that is where the rheumatologist will have the greatest impact,” said Alejandra Magdalena Babini, MD, rheumatologist affiliated with Hospital Italiano de Córdoba, Córdoba, Argentina, and secretary general of the Pan American League of Associations for Rheumatology.

For more than a decade, researchers have warned about the resemblance of chikungunya symptoms to those of RA, although the mechanisms and diagnostic boundaries remain unclear.

Babini explained that chikungunya “gets into the core of patients’ immunity,” inducing high production of interferon alpha and inflammatory cytokines, such as interleukin 4 and interleukin 13, mirroring the patterns seen in reactive arthritis.

A recent study published in Infectious Disease Reports suggested a potential link between immune dysregulation and increased osteoclast activity, which may contribute to persistent joint pain in patients with chronic chikungunya fever.

Chronic symptoms may persist for several years after the acute phase of the disease. A 2016 systematic review and meta-analysis in Arthritis Care and Research reported that nearly 25% of chikungunya cases progress to chronic inflammatory rheumatism related to chikungunya, and the prevalence remains significant even a decade after the infection. “Post-chikungunya arthritis can be extremely destructive, and 7 years later you can still see disease activity,” Babini said.

Diagnostic Nuance

José Kennedy Amaral, MD, is a rheumatologist and researcher in the Postgraduate Program in Health Sciences, Faculty of Medicine, Federal University of Cariri in Barbalha, Brazil.

His research and experience evaluating approximately 2000 individuals with this condition, along with several publications, examined the areas of overlap and distinction between chronic chikungunya arthritis and RA.

He estimated that one third to one half of infected individuals develop chronic inflammatory rheumatism and 10%-15% develop chronic arthritis.

Chronic chikungunya arthritis is “so similar to rheumatoid arthritis that, if the previous chikungunya infection is not known, it may be clinically indistinguishable,” Amaral said in an interview with Medscape’s Spanish edition.

The “typical profile” of a person who develops chronic arthritis similar to RA after chikungunya is that of a middle-aged or older woman who experienced a very symptomatic acute episode marked by high fever, intense polyarthritis, and morning stiffness, Amaral said.

However, the clinical and therapeutic similarities between the two “does not imply that we are facing the same clinical entity, but rather similar final inflammatory pathways in different etiological contexts,” he added.

When asked why it is important to distinguish classic RA from chronic arthritis caused by chikungunya, Amaral replied, “Because although they may look similar clinically, they differ in their natural history. Chikungunya arthritis can follow a more fluctuating course and even show some improvement over time, while rheumatoid arthritis tends to progress continuously.”

He noted that in post-chikungunya arthritis, there is a clear viral trigger, even though some cases may be asymptomatic or labeled simply as viral infections. The autoantibody pattern, such as that of anti-cyclic citrullinated peptide antibodies, is usually less pronounced than that in classic RA, although overlap can occur in some individuals. Memory and concentration problems, fatigue, and depression are also more common in patients with chronic chikungunya arthritis.

“There are also differences in prognosis and in how the patient is guided because it is not the same to face a chronic and potentially lifelong autoimmune disease as it is to face post-viral inflammatory arthritis which, even though it is serious, may have a greater possibility of stabilizing,” he continued.

Mota noted that even though the therapeutic approach is similar, recognizing that the RA phenotype originates from a history of chikungunya requires weighing the intensity of immunosuppression because “overtreatment can do as much harm as not treating the patient.”

Pathogenesis Insights

Experts believe that post-chikungunya chronic arthritis can serve as a “window” into understanding key aspects of RA pathogenesis.

From a conceptual point of view, chikungunya functions as a kind of “natural experiment,” Amaral said. “We observe previously healthy individuals who suffer an intense viral infection and in a fraction of them this stimulus is sufficient to initiate self-sustaining chronic joint inflammation.”

In a recent study, Amaral and colleagues have proposed that part of this process may involve epigenetic reprogramming of bone marrow-derived mesenchymal stem cells, enabling a persistent inflammatory profile even in the absence of ongoing viral replication in the joints.

“In simple terms: Chikungunya arthritis allows us to see, in real time, how an infection can function as a trigger for chronic arthritis very similar to rheumatoid arthritis precisely the question rheumatology has been trying to answer for decades,” he said.

Mota declared receiving honoraria, grants, and consulting fees from AbbVie, Bristol Myers Squibb, Boehringer Ingelheim, Celltrion, J&J, Lilly, Novartis, Pfizer, Organon, Roche, and UCB. Babini declared receiving honoraria, grants, and consulting fees from AbbVie, GlaxoSmithKline, Janssen, Pfizer, Boehringer Ingelheim, and Bristol Myers Squibb. Amaral declared having no relevant conflicts of interest.

This story was translated from Medscape’s Spanish edition.