Detection of Zika virus in saliva

Background: During the largest Zika virus (ZIKV) outbreak ever reported that occurred from October 2013 to March 2014 in French Polynesia, we observed that several patients presenting the symptoms of acute phase Zika fever were tested negative in blood by ZIKV real-time PCR (RT-PCR).

Objectives: As we have previously detected ZIKV RNA in the saliva of a young child, we investigated the use of saliva as an alternative sample for routine ZIKV RNA detection.

Study design: Over a 6 month period, 1,067 samples collected from 855 patients presenting symptoms of Zika fever (saliva only, blood only or both samples) were tested using a specific ZIKV RT-PCR. A medical questionnaire was available for most of the patients.

Results: ZIKV was more frequently detected in saliva compared to blood. For the 182 patients with both samples collected, tests were positive for 35 (19.2%) in saliva while negative in blood and tests were positive for 16 (8.8%) in blood while negative in saliva; the difference in mean days after symptoms onset and the percentage of the main symptoms of Zika fever for patients only positive in saliva or in blood was not significant.

Conclusion: The use of saliva sample increased the rate of molecular detection of ZIKV at the acute phase of the disease but did not enlarge the window of detection of ZIKV RNA. Saliva was of particular interest when blood was difficult to collect (children and neonates especially).