Rheumatic manifestations of chikungunya: emerging concepts and interventions.

The largest epidemic ever recorded for chikungunya, a disease caused by infection with the chikungunya virus (CHIKV), began in Africa in 2004 and spread to >100 countries on four continents. The epidemic caused >10 million cases of often debilitating rheumatic disease, classically involving rapid onset of fever and polyarthralgia, often with polyarthritis. The clinical diagnosis of chikungunya is often complicated by infections with dengue or Zika virus. For many individuals with chikungunya, the disease is benign and self-limiting; however, some patients have a complex spectrum of atypical and severe manifestations. Many patients also experience a chronic phase of the disease, primarily involving arthralgia (which can be protracted (>1 year)), and a number of sequelae are also recognized. CHIKV-induced arthropathy arises from infection of multiple cell types in the joint and the infiltration of mainly mononuclear cells. Innate responses (primarily involving type I interferon responses and natural killer cells) and cognate responses (primarily involving CD4 T helper 1 cells), alongside activation of macrophages and monocytes, mediate CHIKV-induced arthritic immunopathology. Ideally, improved anti-inflammatory treatments should not compromise antiviral immunity. New concepts in mosquito control are being field tested and a number of CHIKV vaccines are being developed.