Zika detection: comparison of methodologies

ABSTRACT Many countries in the Americas have detected local transmission of multiple arboviruses that cause febrile illnesses. Therefore, laboratory testing has become an important tool for confirming the etiology of these diseases. The present study aimed to compare the sensitivity and specificity of three different Zika virus detection assays. One hundred serum samples from patients presenting with acute febrile symptoms were tested using a previously reported TaqMan® RT-qPCR assay. We used a SYBR® Green RT-qPCR and a conventional PCR methodologies to compare the results. Of the samples that were determined to be negative by the TaqMan® RT-qPCR assay, 100% (Kappa = 0.670) were also found to be negative by SYBR® Green RT-qPCR based on Tm comparison; however, 14% (Kappa = 0.035) were found to be positive by conventional PCR followed by agarose gel electrophoresis. The differences between the ZIKV strains circulating worldwide and the low viremia period can compromise diagnostic accuracy and thereby the accuracy of outbreak data. Therefore, improved assays are required to improve the diagnosis and surveillance of arbovirus.

Zika detection: comparison of methodologies.

Many countries in the Americas have detected local transmission of multiple arboviruses that cause febrile illnesses. Therefore, laboratory testing has become an important tool for confirming the etiology of these diseases. The present study aimed to compare the sensitivity and specificity of three different Zika virus detection assays. One hundred serum samples from patients presenting with acute febrile symptoms were tested using a previously reported TaqMan® RT-qPCR assay. We used a SYBR® Green RT-qPCR and a conventional PCR methodologies to compare the results. Of the samples that were determined to be negative by the TaqMan® RT-qPCR assay, 100% (Kappa=0.670) were also found to be negative by SYBR® Green RT-qPCR based on Tm comparison; however, 14% (Kappa=0.035) were found to be positive by conventional PCR followed by agarose gel electrophoresis. The differences between the ZIKV strains circulating worldwide and the low viremia period can compromise diagnostic accuracy and thereby the accuracy of outbreak data. Therefore, improved assays are required to improve the diagnosis and surveillance of arbovirus.

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.