Concomitant Transmission of Dengue, Chikungunya, and Zika Viruses in Brazil: Clinical and Epidemiological Findings From Surveillance for Acute Febrile Illness

AbstractBACKGROUND:Since their emergence in the Americas, chikungunya (CHIKV) and Zika (ZIKV) viruses co-circulate with dengue virus (DENV), hampering clinical diagnosis. We investigated clinical and epidemiological characteristics of arboviral infections during the introduction and spread of CHIKV and ZIKV through northeastern Brazil.METHODS:Surveillance for arboviral diseases among febrile patients was performed at an emergency health unit of Salvador, Brazil between Sep/2014-Jul/2016. We interviewed patients to collect data on symptoms, reviewed medical records to obtain the presumptive diagnoses, and performed molecular and serological testing to confirm DENV, CHIKV, ZIKV, or non-specific flavivirus (FLAV) diagnosis.RESULTS :948 participants, 247 (26.1%) had an acute infection, of which 224 (23.6%) were single infections (DENV: 32, or 3.4%; CHIKV: 159, 16.7%; ZIKV: 13, 1.4%; and FLAV: 20, 2.1%), and 23 (2.4%) co-infections (DENV/CHIKV: 13, 1.4%; CHIKV/FLAV: 9, 0.9%; and DEN/ZIKV: 1, 0.1%). An additional 133 (14.0%) patients had serological evidence for a recent arboviral infection. Patients with Zika presented rash (69.2%) and pruritus (69.2%) more frequently than those with dengue (37.5% and 31.2%, respectively) and chikungunya (22.9% and 14.7%, respectively) (P<0.001 for both comparisons). Conversely, arthralgia was more common in chikungunya (94.9%) and FLAV/CHIKV (100.0%) than in dengue (59.4%) and Zika (53.8%) (P