Dengue, Chikungunya & Zika Virus in VA Caribbean HCS, Nov. 2015-Aug. 2016
Authors: Schirmer Patricia , Oda Gina , Lucero-Obusan Cynthia A. , Winters Mark , Saavedra Sonia , Martinez Mirsonia , Holodniy Mark 
Published: May 2017

ObjectiveWe describe surveillance for Dengue virus (DENV), Chikungunyavirus (CHIKV) and Zika virus (ZIKV) in VA Caribbean HealthcareSystem (VACHS) from the start of ZIKV transmission in Puerto Rico.IntroductionDENV, CHIKV and ZIKV are all transmitted by mosquitoes andhave occurred in outbreaks in the Caribbean. Common symptoms(which can be severe and disabling) are similar among the 3 virusesand include fever, joint pain/swelling, headache, muscle pain andrash. In December 2015, the first endemic case of ZIKV infection wasreported by VACHS. Since that time, an increasing number of ZIKVinfections have been reported in Puerto Rico. Due to the growingZIKV outbreak, we performed ongoing testing and surveillance.MethodsDENV, CHIKV and ZIKV infection surveillance from November2015 - August 2016 at VACHS was performed from 2 primary datasources: (1) VA PraedicoTMPublic Health Surveillance System forlaboratory results documented within the electronic medical record(EMR) and (2) communications with facility clinicians for laboratoryresults not entered into the EMR. Laboratory tests were consideredunique tests if they were performed >30 days apart. A positive testwas defined as a positive IgM or RT-PCR test result. Serial infectionwas defined as infection with CHIKV and ZIKV or CHIKV andDENV. Potential cross-reaction of assays was defined as positiveDENV and ZIKV IgM results within 30 days. Demographic andclinical data was obtained on all positive ZIKV cases including caseswith serial infection.ResultsFor the time period evaluated, 2,218 unique tests were performedfor DENV (744), CHIKV (741), and ZIKV (744). Five hundred thirtythree positive tests were identified for: DENV (34), CHIKV (55) andZIKV (444) (Figure 1). Demographic and virus breakdown of testingis shown in Table 1. Percent positive range for DENV testing was0-23%, for CHIKV was 0-14%, and for ZIKV 0-73%. Temporaltiming of positive tests for each virus by percent positive is depictedin Figure 2. Serial infections were identified in 39 patients (1 CHIKVIgM/ZIKV IgM/PCR+, 7 CHIKV IgM/ZIKV IgM+, 26 CHIKV IgM/ZIKV PCR+, 2 CHIKV IgM/ZIKV PCR/DENV IgM+, 2 DENV IgM/CHIKV IgM+, 1 DENV IgM/CHIKV IgM/ZIKV IgM+). The averageage of patients with serial infection was 63.5 years (range 33-85) andoccurred in 4 females and 35 males. 21 patients were identified withpositive DENV and ZIKV IgM tests, which could represent cross-reactivity between the assays or co-infection. Confirmatory testing ofthese specimens is pending.ConclusionsLaboratory surveillance demonstrated co-circulation of all 3viruses, although ZIKV was the dominant infection identifiedduring this time period. In addition, laboratory data suggests serialinfection with CHIKV and ZIKV while also identifying patients withprobable cross-reaction between DENV and ZIKV tests. Additionalinvestigation is needed to determine whether patients with serialinfection have increased severity of symptoms or different clinicaloutcomes. Since number of ZIKV infections continues to increase andall 3 viruses continue to circulate, continued public health messagingremains important.Figure 1Table 1:VA Caribbean Healthcare System Dengue Virus (DENV),Chikungunya Virus (CHIKV) and Zika Virus (ZIKV) Demographics andTesting, Nov. 2015-Aug. 2016