846. Postnatally Acquired Zika Virus (ZIKV) Infection in Infants and Young Children in Guatemala: Serologic and Neurodevelopmental (ND) Evaluation

BACKGROUND: Diagnosing ZIKV infection in children in dengue (DENV) endemic regions is challenging. The kinetics and effects of maternal Ab on infant infection responses remain unknown, as do the ND effects of ZIKV acquired in early life. METHODS: This is a population-based prospective cohort study in infant–mother pairs and children <5 years in a rural DENV endemic area of Guatemala evaluating the incidence and ND outcomes of postnatally cquired ZIKV infection. Subjects were followed 1 year for symptoms of flavivirus-like illness (FLI), serologic and virologic evidence of ZIKV or DENV infection and ND outcomes. ZIKV and DENV neutralizing antibodies (NAb) were measured at enrollment and longitudinally. Subjects were classified as ZIKV- or DENV-infected based on NAb. Specimens from acute illnesses were tested for viral RNA by rRT-PCR. ND was assessed at enrollment and longitudinally using an adapted Mullen Scales of Early Learning (MSEL). RESULTS: In total, 1,371 subjects (374 children 1–5 years, 500 infants, 497 mothers) were enrolled from June 2017 to July 2018. Among 1,335 evaluable subjects, 7.6% (101) had serologic evidence of recent ZIKV infection (NAb >500 or >100 and DENV-neg); 13.2% (176) were DENV-pos only; 44.8% (598) were ZIKV-neg (NAb15 −<100) or low (<500) ZIKV and DENV NAb, suggesting prior flavivirus infection or cross-reactivity (Figures 1 and 2). ZIKV infection alone was more prevalent in children 1–5 years, while infants’ serologic pattern was similar to that of their mothers. One child ZIKV seroconverted. In 391 FLI episodes (67 children 1–5 years and 215 infants with fever, rash, myalgia, and conjunctivitis; 109 mothers with fever, myalgia, and joint pain), acute DENV infections, but not ZIKV, were identified by rRT-PCR. MSEL scores were similar to US norms in infants <12 m (composite mean 94.8, SD 11.9), but lower in children 1–5 years in all domains (mean 75.1, SD 17.4, P < 0.0001) (Figure 3). CONCLUSION: Serologic evidence of recent ZIKV infection, but no acute ZIKV, was documented in young children in Guatemala. Infant seroreactivity derives from prior maternal infection and DENV cross-reactivity. Observed substantial differences in ND scores between infants and children 1–5 years challenge the ability to isolate the potential effects of ZIKV infection in early life. NIAID Contract HHSN272201300015I Task Order HHSN27200013. FMM and EJA Co-PIs. [Image: see text] [Image: see text] [Image: see text] DISCLOSURES: Flor M. Munoz, MD, Biocryst: Grant/Research Support; CDC: Research Grant; Moderna: Other Financial or Material Support, Safety Monitoring Board Member/Chair; NIH: Research Grant; Novavax: Research Grant; UP to Date: Author and Editor: Royalties, Other Financial or Material Support.