The Zika virus (ZIKV) circulates in the Caribbean island of Curacao since January 2016. Since that time, the public health laboratory in Curaçao has tested nearly 800 patients Fig 1a. At the start of the epidemic, the choice was made to perform RT-PCR on urine samples instead of plasma. The reason for this choice was that the diagnostic window for ZIKV PCR in urine was reported to be significantly longer than the short window reported for plasma. This abstract reports the diagnostic performance of ZIKV NS5 detection by PCR in urine samples of acutely ill patients.
Both primary care physicians and gynaecologists tested patients based on a more stringent version of the WHO case definition requiring rash and/or conjunctivitis. Urine was required to be collected within 10 days of onset of symptoms. ZIKV RNA was tested in urine of patients from January to June 2016. Quantitative real-time PCR detection of the Zika NS5 protein gene, 1083 bp. long fragment, was performed with a commercially available kit on the LightCycler 480 II platform.
In the first 24 weeks of the outbreak in Curaçao, 777 patients were tested. 537 (69%) patients were female, indicating that females were tested twice as frequent as male patients, Figure 2A. The majority of tests were requested by primary care physicians, Figure 2B. Positive PCR results were found in every week totaling 144 out of 777 patients (19%). In some weeks, the percentage of positive patients was as high as 60%, figure 1B.
Zika RNA PCR in urine has shown the highest sensitivity in any population plagued by Zika virus so far. The enhanced sensitivity of ZIKV PCR in urine samples is most likely the effect of the prolonged diagnostic window when urine is compared to plasma. Urine samples should be considered over plasma samples for the detection of ZIKV by PCR in diagnostic algorithms.
FIG. 1:. (A) Cumulative number of tests and positive ZIKV PCR results by week. (B) Tests and ZIKV PCR positive results by week.
FIG. 2: (A) The number of female and male patients that were tested for ZIKV. (B) Applicants for ZIKV PCR.
C. Roggeveen, None
L. Virginia-Cova, None
R. Steingrover, None