Investigation of Zika virus infection Incidence among Measles-and Rubellanegative patients in Measles Elimination Program in Thailand, 2016

Abstract

Background: In 2012-2014, there were 47 cases from 4 unknown etiology fever rash outbreaks in Thailand. All cases were negative by antibody test for measles, rubella and negative by PCR for chikungunya and dengue. All 47 samples were tested by US CDC Laboratory at Ft Collin Colorado, found that 7 cases were detected Zika virus (ZV). This study aimed to identify an incidence of Zika virus infection (ZVI) among negative measles and rubella cases in the measles elimination program (MEP) of Thailand in 2016.
Methods: The study population in MEP, was patients who have negative for measles virus, rubella virus, and a blood sample sufficient for detection of ZV by RT-PCR and Molecular sequencing methods. To describe and to compare the epidemiological characteristics, clinical presentations between measles-confirmed patients (418) and confirmed ZVI patients.
Results: Total 154 cases were found inclusion criteria for testing ZV by PCR in acute blood. Of those, 6 cases were detected for ZV genome, the incidence was 3.90%. All were female, median age was 25 years old with age range 4–29 years old. All were living in the central region. Five cases were in a same district in Kanchanaburi and another one was in Lopburi. Their onset of Kanchanaburi cases were in March 2016 and Lopburi case was in September 2016, were also matched with the epidemic of ZV in the provinces. The most common clinical presentation of confirmed ZVI was febrile and rash. But conjunctivitis and joint pain were more common in ZVI. The different epidemiological characteristics between ZVI and confirmed measles were age group, vaccination history and hospitalization (with imply a severity). The ZVI was common in adult (66%) but median age in measles cases was 3 years. Completed measles vaccination was observed higher in ZVI (83.33%) compare to confirmed measles (10%).
Conclusion & Recommendations: For this study demonstrate the possibility of implement ZV surveillance in the MEP in particular groups such as the adults (age above 15 years), complete measles vaccination, and clinical presentations with conjunctivitis with joint pain. We also recommend to immediate collect urine for ZV testing after measles and rubella were returning negative.