Chikungunya fever: How accurate is the clinical-epidemiological diagnosis compared to the gold standard of molecular and serological laboratory diagnosis?

To evaluate the accuracy of the current World Health Organization' (WHO) Chikungunya fever (CHIKF) clinical-epidemiological case definition against the gold standard of laboratory diagnosis. This was a prospective study of patients seeking medical care at an Emergency Department in the metropolitan area of Rio de Janeiro, Brazil, from January to June 2018. Clinical features were recorded. Screening for CHIKF was performed using the RT-qPCR and ELISA-IgM antibody assay. Clinical features of CHIKF RT-qPCR/IgM positive cases were compared with those with other febrile illnesses. 27,900 ED visits were recorded, of which 172 (0.61 %) patients were screened for arboviral illness. The prevalence of laboratory-confirmed CHIKF (Lab-CHIKF) was 110/172 [64 %]. Chikungunya virus RNA was detected in 92/172 (53.5 %) patients, while in 18/80 (10.5 %), only IgM was positive. Compared to CHIKV-negative subjects, patients with CHIKF presented much earlier after the onset of symptoms (2 [1–4] vs. 3.5 [2.5−5], p = 0.007), and more frequently reported arthritis (61.8 % vs. 33.9 %, p