This is the first report to describe the frequency of chikungunya virus-related arthritis in the Americas after a 20-month follow-up. The high frequency of chronic disease highlights the need for the development of prevention and treatment methods.

Objective. This study aimed to identify the co-circulation patterns of three viruses (dengue, Zika, and ­chikungunya) in Colombia from 2008 to 2018 by using notification reports provided to the national surveillance system. Methods. This cross-sectional study was conducted through a review of data for 2008 through 2018 from Colombia’s Public Health Surveillance System (SIVIGILA). Results. In 2015, when chikungunya was first detected, it had a higher incidence (1 359.0 cases per 100 000 persons) than did the two other diseases. In 2016, when the circulation of Zika virus was first found, the incidence was 296.4 cases per 100 000 persons; that incidence declined dramatically in the next two years. Between 2015 and 2018, there was a substantial decrease in the frequency of dengue circulation, with it going from 334.1 cases per 100 000 persons in 2015 to 90.7 cases per 100 000 in 2017 and 173.1 cases per 100 000 in 2018. Conclusions. The decrease in the number of dengue cases after co-circulation of the three viruses could indicate possible cross-protection. This finding should be further analyzed.

This is one of the largest observational studies involving analysis of the synovial fluid of chikungunya arthritis patients. Synovial fluid analysis revealed no detectable chikungunya virus. This finding suggests that chikungunya virus may cause arthritis through induction of potential host autoimmunity, suggesting a role for immunomodulating agents in the treatment of chikungunya arthritis, or that low-level viral persistence exists in synovial tissue only and is undetectable in synovial fluid.

Most alphaviruses are mosquito-borne and can cause severe disease in domesticated animals and humans. The most notable recent outbreak in the Americas was the 2014 chikungunya virus (CHIKV) outbreak affecting millions and producing disease highlighted by rash and arthralgia. Chikungunya virus is a member of the Semliki Forest (SF) serocomplex, and before its arrival in the Americas, two other member of the SF complex, Una (UNAV) and Mayaro (MAYV) viruses, were circulating in Central and South America. This study examined whether antibodies from convalescent CHIKV patients could cross-neutralize UNAV and MAYV. Considerable cross-neutralization of both viruses was observed, suggesting that exposure to CHIKV can produce antibodies that may mitigate infection with UNAV or MAYV. Understanding the impact of CHIKV exposure on population susceptibility to other emerging viruses may help predict outbreaks; moreover, identification of cross-reactive immune responses among alphaviruses may lead to the development of vaccines targeting multiple viruses.

The cytokine profile during acute chikungunya infection that predicts future chronic arthritis has not yet been investigated. We conducted a nested case-control study comparing serum cytokine concentrations during acute chikungunya infection in cases (n = 121) that reported the presence of chronic joint pain versus age- and gender-matched controls (n = 121) who reported recovery at 20 months post infection. We observed that a robust cytokine response during acute infection was correlated with a decreased incidence of chronic joint pain and that low TNFα, IL-13, IL-2, and IL-4 during acute infection was predictive of chronic joint pain. These data suggest that a robust cytokine response is necessary for viral clearance and cytokines that are related to immune tolerance during acute infection may be protective for chronic arthritis pathogenesis.