Abstract
Introduction: Zika virus infection and its consequences have become increasingly concerned
recently. As a member of Flaviviruses, zika virus shares some clinical dengue fever manifestations. The
actual burden of zika virus infection in Thailand is unclear, and could be underestimated due to nonspecific
clinical pictures and the diagnostic testing has not been routinely available. We aim to study
the zika incidence among the suspected dengue fever patients. Methodology: From December 2016
to August 2017, adult and children who had clinical diagnosis of dengue fever at Bamrasnaradura Infectious
Diseases Institute were prospectively enrolled. After informed consent, a urine sample would
be collected for zika molecular testing by polymerase chain reaction (PCR). At 2 weeks later, a blood
sample was collected for zika and dengue serologic tests by ELISA. Results: A total of 73 suspected
dengue fever patients were enrolled; 64 were hospitalized, 46 cases were children (< 15 years of age).
The ratio of children to adult was 1.7:1. There were 3 confirmed zika-infected cases by urine PCR, a
4.1% incidence. All were adult treated as outpatients. The cases were found during June–August. All 3
cases had positive anti zika IgG (mean titer of 4.43 unit, range: 2.6-6.9 unit), but anti-zika IgM was found
to be positive (titer 2.9 unit), indeterminate (titer 0.9 unit) and negative (0.4 unit), one case each. All
had negative anti-dengue IgG or IgM titer. Conclusions: The patients presented with dengue fever may
actually had zika infection, although at low rate. The anti-zika IgM was not useful in making diagnosis.
High risk group such as pregnant women who presented with dengue fever should be tested for zika
infection.
