Clinical, laboratory and virological data from suspected ZIKV patients in an endemic arbovirus area.

BACKGROUND: The emergence of Zika virus (ZIKV) presents new challenges to both clinicians and public health authorities. Overlapping clinical features between the diseases caused by ZIKV, dengue (DENV) and chikungunya (CHIKV) and the lack of validated serological assays for ZIKV make accurate diagnosis difficult. Brazilian authorities largely rely on clinical and epidemiological data for the epidemiological and clinical classifications of most ZIKV cases. OBJECTIVE: To report the laboratory and clinical profiles of patients diagnosed with Zika fever based only on clinical and epidemiological data. STUDY DESIGN: We analyzed 433 suspected cases of ZIKV identified by the attending physician based on proposed clinical criteria. The samples were also screened for ZIKV, DENV and CHIKV using PCR. RESULTS: Of the 433 patients analyzed, 168 (38.8%) were laboratory-confirmed for arboviruses: 96 were positive for ZIKV, 67 were positive for DENV (56 for DENV-2, 9 for DENV-1, and 2 for DENV-4), four were positive for co-infection with ZIKV/DENV-2, and one was positive for CHIKV. The most common signs or symptoms in the patients with laboratory-confirmed ZIKV were rash (100%), arthralgia (77.1%), fever (74.0%), myalgia (74.0%) and non-purulent conjunctivitis (69.8%). In patients with laboratory-confirmed DENV infections, the most frequently observed symptoms were rash (100%), fever (79.1%), myalgia (74.6%), headache (73.1%) and arthralgia (70.1%). The measure of association between clinical manifestations and laboratory manifestations among patients with ZIKV and DENV detected a statistically significant difference only in abdominal pain (p=0.04), leukopenia (p=0.003), and thrombocytopenia (p=0.01). CONCLUSION: Our data suggests that clinical and epidemiological criteria alone are not a good tool for ZIKV and DENV differentiation, and that laboratory diagnosis should be mandatory.

Dengue-4 false negative results by Panbio® Dengue Early ELISA assay in Brazil.

BACKGROUND: Dengue is a serious public health problem in numerous countries. The ability to rapidly diagnosis dengue is important for patient triage and management. Detection of dengue viral protein, NS1, represents a new approach to dengue diagnosis. OBJECTIVE: The present study aims to evaluate if there are false negative results using the NS1 Ag rapid assay (Panbio(®) Dengue Early ELISA) in two different epidemiological situations (epidemic and non-epidemic). STUDY DESIGN: 220 serum samples from patients with clinical symptoms of classical dengue fever were tested by NS1 antigen capture ELISA and Multiplex-Nested-PCR. RESULTS: In samples collected in a non-epidemic period we found a 100% agreement of ELISA and RT-PCR in dengue negative samples and 85% agreement of ELISA and RT-PCR in dengue positive samples. But when we tested samples during an epidemic period (large DENV-4 outbreak) we found 15% false negative results (p<0.05) in dengue negative samples. CONCLUSIONS: Due to false negative results for DENV-4, the sole use of the Panbio(®) Dengue Early ELISA assay as a screening method for monitoring circulating dengue serotypes must be reevaluated.