Zika virus infection in Nicaraguan households

• Authors: Raquel Burger-Calderon, University of California; Karla Gonzalez, Sustainable Sciences Institute; Sergio Ojeda, Sustainable Sciences Institute; José Victor Zambrana, Sustainable Sciences Institute; Nery Sanchez, Sustainable Sciences Institute; Cristhiam Cerpas Cruz, Sustainable Sciences Institute; Harold Suazo Laguna, Sustainable Sciences Institute; Fausto Bustos, University of California; Miguel Plazaola, Sustainable Sciences Institute; Brenda Lopez Mercado, Sustainable Sciences Institute; Douglas Elizondo, Sustainable Sciences Institute; Sonia Arguello, Sustainable Sciences Institute; Jairo Carey Monterrey, Sustainable Sciences Institute; Andrea Nunez, Sustainable Sciences Institute; Josefina Coloma, University of California; Jesse J. Waggoner, Emory University; Aubree Gordon, University of Michigan; Guillermina Kuan, Ministry of Health; Angel Balmaseda, Sustainable Sciences Institute; Eva Harris, University of California
• Journal Title: PLoS Neglected Tropical Diseases
• Volume: Volume 12, Number 5
• Publisher: Public Library of Science | 2018-05-01, Pages e0006518-e0006518
• Type of Work: Article | Final Publisher PDF
• Publisher DOI: http://doi.org/10.1371/journal.pntd.0006518
• Subjects: Health Sciences, Medicine and Surgery; Health Sciences, Public Health
• Keywords: Science & Technology; Life Sciences & Biomedicine; Infectious Diseases; Parasitology; Tropical Medicine; SEXUAL TRANSMISSION; DISEASE; COHORT; SALIVA; BRAZIL; CHIKUNGUNYA; MARTINIQUE; ANTIBODIES; DIAGNOSIS; MOSQUITOS

Abstract

Zika virus (ZIKV) infection recently caused major epidemics in the Americas and is linked to congenital birth defects and Guillain-Barré Syndrome. A pilot study of ZIKV infection in Nicaraguan households was conducted from August 31 to October 21, 2016, in Managua, Nicaragua. We enrolled 33 laboratory-confirmed Zika index cases and their household members (109 contacts) and followed them on days 3–4, 6–7, 9–10, and 21, collecting serum/plasma, urine, and saliva specimens along with clinical, demographic, and socio-economic status information. Collected samples were processed by rRT-PCR to determine viral load (VL) and duration of detectable ZIKV RNA in human bodily fluids. At enrollment, 11 (10%) contacts were ZIKV rRT-PCR-positive and 23 (21%) were positive by IgM antibodies; 3 incident cases were detected during the study period. Twenty of 33 (61%) index households had contacts with ZIKV infection, with an average of 1.9 (range 1–6) positive contacts per household, and in 60% of these households, ≥50% of the members were positive for ZIKV infection. Analysis of clinical information allowed us to estimate the symptomatic to asymptomatic (S:A) ratio of 14:23 (1:1.6) among the contacts, finding 62% of the infections to be asymptomatic. The maximum number of days during which ZIKV RNA was detected was 7 days post-symptom onset in saliva and serum/plasma and 22 days in urine. Overall, VL levels in serum/plasma, saliva, and urine specimens were comparable, with means of 5.6, 5.3 and 4.5 log10copies/ml respectively, with serum attaining the highest VL peak at 8.1 log10copies/ml. Detecting ZIKV RNA in saliva over a similar time-period and level as in serum/plasma indicates that saliva could potentially serve as a more accessible diagnostic sample. Finding the majority of infections to be asymptomatic emphasizes the importance of silent ZIKV transmission and helps inform public health interventions in the region and globally.