How many patients with post-chikungunya chronic inflammatory rheumatism can we expect in the new endemic areas of Latin America?

Post-chikungunya chronic inflammatory rheumatism (pCHIK-CIR) is one of the consequences that are impacting new endemic countries, such as those in the Americas. The relative frequency of pCHIK-CIR is highly variable, ranging from 14.4 % to 87.2 % (including variable number of patients and follow-up times). Based on those non-weighted values, it is difficult to estimate which would be the expected number of patients with CHIK who will develop CIR. For these reasons, we modeled weighted estimations based on pooled data extracted from those eight representative studies in order to provide cumulative proportion of pCHIK-CIR over time and median time of it, but also estimations of the number of patients with CHIK reported in Latin American countries (within a 95 % CI). This model estimated a prevalence of 47.57 % for pCHIK-CIR (95 % CI 45.08–50.13), with a median time to 50 % of pCHIK-CIR in 20.12 months. Given the reported number of patients with acute CHIK during 2014 in the Americas, our estimates suggest that from those patients, 385,835–429,058 patients will develop pCHIK-CIR. Despite the limitations of these estimates, the provided figures of pCHIK-CIR presented here are preliminary approximations of what the future burden of related rheumatic disease in the region as a consequence of CHIK infection for 2015–2016 could be, given the timeframe of median time of occurrence.