Active syndromic surveillance program of arboviruses in Rio de Janeiro, Brazil

Abstract

Purpose: Recently, new arbovirus such as Zika virus (ZIKV) and Chikungunya virus (CHIKV) were introduced in Brazil. Despite the clinical relevance, to date there is no syndromic surveillance system focused in arbovirosis in Brazil. Here, we present the initial results of active syndromic surveillance system for arbovirus infections in Rio de Janeiro, Brazil. Methods & Materials: This is a hospital-based prospective multicenter transversal study. Inclusion criteria were: Presence of fever AND/OR exanthema, with maximal duration of 7 days; PLUS: 2 or more nonspecific symptoms OR a clinical suspicion of arbovirus infection. Patients who met inclusion criteria had blood and urine tested for ZIKV, CHIKV and DENV by RT-PCR. Clinical data were collected using REDCap standardized form. Results: From March 14th to May 31th of 2016 (epidemiological weeks 11 to 22) 269 patients were included in the study. Patients were predominantly female (57.7%), with mean age of 41.9 years old. One hundred ninety patients (71.1%) were PCR-positive for at least one of the arbovirus tested, 4 patients were infected simultaneously by 2 arbovirus (3 ZIKV/CHIKV and 1 ZIKV/DENV4 (co-infection); 79 patients (29.4%) were PCR-negative. Among PCR-positive samples, 146 (54.3%) were confirmed for CHIKV, 36 (13.4%) were confirmed for ZIKV and 8 (3.0%) were confirmed for DENV (1 DENV3 and 7 DENV4). Over time, dengue cases were distributed between EW 11 to 13, most ZIKA cases (63.9%) between EW 12 to 15 and CHIKV cases were almost evenly distributed along the time study interval. Median time (days) between symptoms onset and PCR confirming diagnosis were 2.0 (IQR 2.0 – 4.25), 2.0 (IQR 1.5 – 3.0) and 4.5 (IQR 3.0 – 6.5), for ZIKV, CHIKV and DENV, respectively. Fever and arthralgia were the most frequent symptoms among CHIKV (90% and 89%) and ZIKV cases (78% and 75%); fever (88%) and headache (88%) were the most frequent symptoms among DENV. Conclusion: Co-circulation of dengue, Zika and CHIK has been observed Rio de Janeiro with direct impact on surveillance, diagnostic and management of the cases. Establishing an active syndromic surveillance system focused in arboviruses is paramount for a fast and precise public health response to these new arbovirus infections.