Imported cases of Chikungunya in Barcelona in relation to the current American outbreak

Background: The Chikungunya virus (CKIKV) is currently present in America. Travel between America and Europe is particularly intense and one of the main vectors of CHIKV, Aedes albopictus, is well established in the Mediterranean basin. We describe a series of imported cases that could originate a European outbreak. Methods: We retrospectively studied cases of CHIKV originating in America and diagnosed in the last year in three Tropical Medicine Units of Barcelona of the International Health Program of the Catalan Health Institute (PROSICS). Clinical, microbiological and epidemiological data were analyzed. Results: Forty-two CHIKV cases who had returned from 11 American countries were included. Fever was the most common symptom at onset (96.1%). Three months after symptom onset 50% continued with arthralgias, 35.3% fatigue and 11.8% arthritis. Three patients were viremic at the time of diagnosis by RT-PCR, and the remaining were diagnosed by serology (CHIKV IgM or IgG). Five (11.9%) patients had positive IgM for both dengue virus and CHIKV. Conclusions: The origin of the cases was diverse, the most frequent being initially the Dominican Republic, followed later by Venezuela and Colombia. Symptoms were not severe but persisted, accompanied by unremitting positive IgM. Diagnosis was mainly based on serology and RT-PCR, with the performance of the rapid immunochromatographic test being low. Phylogenetic studies showed that two viremic cases were caused by a strain of Asian lineage with a lower adaptability to Aedes albopictus. Co-infection with the dengue virus was common, but the clinical course was not affected by coinfection. Non-steroidal anti-inflammatory drugs were administered to 71.4% and steroids to 21.4%. The number of imported cases of CHIKV in Spain is rising due to introduction of this virus in America, and this could lead to an autochthonous outbreak if Public Health measures are not taken.