Risk Factors Associated with Persistence of Zika Virus Nucleic Acid in Serum and Semen

BACKGROUND: Identifying factors associated with time-to-loss of Zika virus (ZIKV) RNA in serum and semen is important to inform diagnostic testing and prevention recommendations. CDC currently recommends RT-PCR testing of serum up to two weeks after symptom onset. We evaluated such associations among participants of the Zika virus Persistence (ZiPer) study in Puerto Rico. METHODS: Patients presenting for care with Zika-like illness and ZIKV RNA detected by RT-PCR in serum or urine (index cases) were offered study participation. Index cases’ household members were offered study participation, and those with detectable ZIKV RNA were eligible for the prospective cohort. Serum and semen were collected weekly for the first month, and biweekly thereafter for participants with detectable ZIKV RNA in any fluid and at 2, 4, and 6 months post-enrollment for all others. We used chi-squared and Fischer’s exact tests to assess if detecting ZIKV RNA in specific specimens at any point was associated with sex, age, Zika-like symptoms (rash, fever, arthralgia, or conjunctivitis), or pregnancy. We performed Weibull regression models to estimate time-to-loss of ZIKV RNA in days post symptom onset (DPO) and evaluated associations between covariates and duration of detection. RESULTS: Among 295 participants, 260 (88.1%) had ZIKV RNA detected in serum at any point. Participants aged ≥18 years (n = 244) had a significantly longer median time-to-loss of ZIKV RNA in serum than participants aged < 18 years (n = 50) (13.1 vs. 7.8 DPO, respectively; P = 0.003) (Figure 1). Among women aged 18–39 years (n = 60), pregnant women (n = 9) had a significantly longer median time-to-loss of ZIKV RNA in serum than non-pregnant women (n = 51) (37.4 vs. 15.5 DPO, respectively; P = 0.0005) (Figure 2). The proportion of men who had detectable ZIKV RNA in semen at any point was significantly higher among men with conjunctivitis (47 of 82) than among men without conjunctivitis (3 of 14) (P = 0.01). No other associations were significant. CONCLUSION: Time-to-loss of ZIKV RNA in serum was longer among adults than children, and conjunctivitis was associated with detecting ZIKV RNA in semen. This study provides evidence that time-to-loss of ZIKV RNA is longer among pregnant women than non-pregnant women. Findings may inform the recommended period to test pregnant women for ZIKV using RT-PCR. DISCLOSURES: All authors: No reported disclosures.