Zika virus RNA excretion in sweat with concomitant detection in other body fluid specimens

Abstract

We evaluated sweat, blood and urine specimens obtained from an ongoing cohort study in Brazil. Samples were collected at pre-established intervals after the initial rash presentation and tested for Zika virus (ZIKV) RNA presence by real-time reverse transcriptase polymerase chain reaction (rRT-PCR). From 254 participants with confirmed infection, ZIKV RNA was detected in the sweat of 46 individuals (18.1%). Sweat presented a median cycle threshold (Ct) of 34.74 [interquartile range (IQR) 33.44-36.04], comparable to plasma (Ct 35.96 - IQR 33.29-36.69) and higher than urine (Ct 30.78 - IQR 28.72-33.22). Concomitant detection with other specimens was observed in 33 (72%) of 46 participants who had a positive result in sweat. These findings represent an unusual and not yet investigated virus shedding through eccrine glands.

Fig. 1:. (A) Zika virus (ZIKV) infection confirmation by real time reverse transcriptase polymerase chain reaction (rRT-PCR). ZIKV RNA detection in sweat samples from 46 participants of 254 confirmed infection cases in Manaus, northern Brazil, analyzed at different time points (according to days of rash report). Detections in sweat at two distinct time points were reported for five participants: (participant IDs 6, 25, 27, 34, and 37). A single participant was defined as asymptomatic household contact (participant 12 - asterisk). Blue dots - ZIKV detection in sweat. Gray dots - detection at other body fluid (blood, urine, or semen, not specified on the figure) according to days post rash.

Fig. 2:. (A) Zika virus (ZIKV) RNA detection by real time reverse transcriptase polymerase chain reaction (rRT-PCR) according to the days of symptoms onset (days post rash report - “x” axis), Cycle threshold (Ct) rRT-PCR value (“y”axis) and body fluid specimen (urine, plasma and sweat) (figure legend colors). (inset) Median Ct value from 46 participants with positive rRT-PCR result in urine, plasma, and sweat body fluid specimens. Cut-off values were set above Ct 38 on rRT-PCR result. Ct - cycle threshold. NS: not significant; ***p < 0.001 analyzed by One-way ANOVA. (B) ZIKV RNA concomitant detection according to the body fluid specimen analyzed. rRT-PCR concomitant detection (“y” axis) refers to an individual positive detection on that specimens from the same participant (as specified on figure legend) according to its study number identification.