Background: Chikungunya virus (CHIKV) causes a disease characterized by acute onset of fever accompanied by arthralgia. Clinical similarities and co-circulation of other arboviruses such as Dengue virus (DENV) and Zika virus (ZIKV), have complicated their differentiation, making their diagnoses a challenge for the health authorities. Misdiagnosis is a serious issue to the management of patients and development of public health measures. Objectives: We carried out further screening of CHIKV, DENV and ZIKV cases in Minas Gerais, Brazil, after diagnostics were already issued by a state laboratory and according to the Brazilian Ministry of Health (BMH) policy. Our aim was to look for possible co-infections or previous arboviruses' exposure. Study design: Sera from 193 patients with symptoms of arboviral infections were tested for DEV, ZKV and/or CHIKV by the State laboratory, according to clinical suspicion and following standard BMH guidelines. After an official diagnosis was issued for each patient, we retested samples applying a broader panel of ELISA-based serological tests. Results: We identified 13 patients with concurrent or consecutive infections (IgM positive for more than one arbovirus), including 11 individuals that were positive for CHIKV and other previously confirmed arbovirus infection. Discussion: Guidelines established in many arbovirus-endemic countries prioritizes the diagnosis of Zika and Dengue and no further analyzes are done when samples are positive for those viruses. As a result, possible cases of co-infections with chikungunya are neglected, which affects the epidemiological assessments of virus circulation, patient management, and the development of public health policies.

Chikungunya is a mosquito-borne infectious disease, which causes acute fever and joint pain, and can trigger long term arthritis. In the present study, we demonstrate a label-free detection of chikungunya virus non-structural protein 3 (CHIKV-nsP3), which is responsible for alphavirus replication, using electrochemical impedance spectroscopy (EIS). This is hitherto, the first work addressing the detection of CHIKV-nsP3 using biosensors. The immunosensors were developed by modifying a gold surface using self-assembled monolayer of 11-mercaptoundecanoic acid and 6-mercaptohexanol. Anti-CHIKV-nsP3 antibodies were attached to the sensor surface via cabodiimide coupling reaction. The impedance spectra were fit to an equivalent circuit, and the percentage change in charge transfer resistance was correlated to the antigen concentration, and a linear working range from 25 ng/ml to 1 mu g/ml of CHIKV-nsP3 was obtained. The limit of detection was 8 ng/ml and the limit of quantification was 17 ng/ml. The biosensor was also found to be highly specific to CHIKV-nsP3. The sensor was further tested for matrix effect from human serum, and appreciable recoveries ranging from 97% to 106% was observed. The results illustrate the potential of EIS based immunosensors with CHIKV-nsP3 as a suitable biomarker for direct and sensitive detection of chikungunya. (C) The Author(s) 2019. Published by ECS.