Epidemiological characteristics of a Zika outbreak in Portoviejo, Ecuador, 2016

ABSTRACT Objective To estimate the number and percentage of cases with Zika diagnosis at a hospital in Portoviejo, Manabi, Ecuador. Methods This was a hospital-based, retrospective, observational, descriptive, cross-sectional study conducted at the Dr. Verdi Cevallos Balda Hospital from January – August 2016. A secondary analysis of a database was performed to estimate the number and percentage of patients positive for Zika virus, by sex, age group, ethnicity, and type of medical care. Prevalence and odds ratios with 95% Confidence Intervals were calculated using the Mantel and Haenszel method. Laboratory diagnostics included assays for the detection of Zika, chikungunya, dengue, and others. Results In all, 467 suspected cases of Zika were identified based on clinical criteria. Of these, 148 cases (31.7%) were confirmed by detection of ZIKV RNA. The peak of the outbreak was documented in May – July 2016 during the rainy season, following the earthquake of April 2016. The adjusted odds ratios indicated that Zika virus was less likely in men and in subjects < 20 years of age. Most of the infected pregnant women (61%) were in the second trimester of pregnancy. No cases of microcephaly were reported. Conclusions Because Zika was more likely to occur among women and those ≥ 20 years of age, surveillance of these groups is imperative to avoid transmission to newborns. Future studies that address the research gap and inform the country's Zika control efforts are recommended.