RT Journal Article
SR Electronic
T1 The burden of dengue fever and chikungunya in southern coastal Ecuador: Epidemiology, clinical presentation, and phylogenetics from a prospective study in Machala in 2014 and 2015
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 102004
DO 10.1101/102004
A1 Anna M. Stewart-Ibarra
A1 Aileen Kenneson
A1 Christine A. King
A1 Mark Abbott
A1 Arturo Barbachano-Guerrero
A1 Efraín Beltrán-Ayala
A1 Mercy J. Borbor-Cordova
A1 Washington B. Cárdenas
A1 Cinthya Cueva
A1 Julia L. Finkelstein
A1 Christina D. Lupone
A1 Richard G. Jarman
A1 Irina Maljkovic Berry
A1 Saurabh Mehta
A1 Mark Polhemus
A1 Mercy Silva
A1 Sadie J. Ryan
A1 Timothy P. Endy
YR 2017
UL http://biorxiv.org/content/early/2017/05/17/102004.abstract
AB Background Dengue (DENV), chikungunya (CHIKV) and Zika (ZIKV) viruses are transmitted by the Ae. aegypti mosquito and present a major public health concern throughout the tropics and subtropics. Here we report the methods and findings from the first two years (January 1, 2014 to December 31, 2015) of an active and passive surveillance study conducted in the southern coastal city of Machala, Ecuador, where DENV is endemic.Methodology/Principal Findings Individuals whom presented at one of four sentinel clinics or the central hospital of the Ministry of Health with suspected DENV infections (index cases) were recruited into the study (n = 324). A subset of DENV positive index cases (n = 44) were selected, and individuals from the index household and four neighboring households within a 200-meter radius (associates) were recruited (n = 397). In 2014, 72.5% (132/182) of index patients and 35.6% (106/298) of associates had evidence of acute or recent DENV infections. In 2015, 28.3% (35/124) of index patients and 12.85% (11/86) of associates, had acute or recent DENV infections. For every case of dengue detected by passive surveillance, we detected an additional three infections in associates. Of associates with DENV infections, slightly more than half showed symptoms. The burden of symptomatic dengue was greatest in children under 10 years of age. The first CHIKV infections were detected in 2015 on epidemiological week 12. There were 50 index cases with acute CHIKV infections (50/122; 41%), including six with both acute CHIKV and acute or recent DENV infections. There were four associates with CHIKV infections (4/87, 4.6%), including one associate with both an acute CHIKV and recent DENV infection. No ZIKV infections were detected. Phylogenetic analyses of isolates of DENV from 2014 revealed genetic relatedness and shared ancestry of DENV1, DENV2 and DENV4 genomes from Ecuador with those from Venezuela and Colombia, as well as more than one introduction of the same serotype into Ecuador, indicating presence of viral flow between Ecuador and the surrounding countries.Conclusions/Significance The results of this active surveillance study provide a more accurate estimate of the symptomatic and subclinical burden of DENV and CHIKV infections and illness across age groups than has previously been detected through traditional passive surveillance.Author summary Dengue and chikungunya viruses are transmitted to people by Aedes sp. mosquitoes in tropical and subtropical regions. Human infections are underreported in traditional public health systems due to a high proportion of infections with mild or no symptoms. This results in an underestimate of the true burden of disease. In this study, we investigated dengue, chikungunya, and Zika infections in an urban center in southern coastal Ecuador in 2014 and 2015, an area known to be endemic for dengue. Patients with symptomatic dengue infections were referred from Ministry of Health sentinel clinics. We visited the households of patients and neighboring homes to identify additional people with infections. We found that the burden of illness due to dengue was greatest in children under 10 years of age. For every case of dengue detected by standard surveillance, we detected an additional three infections in the community. Of people in the community with dengue infections, slightly more than half showed symptoms. The first chikungunya infections were detected in March 2015. Genetic analyses indicate that there is movement of the dengue virus among Ecuador, Venezuela and Colombia. The results of this enhanced surveillance study provide a more accurate estimate of the symptomatic and subclinical burden of dengue and chikungunya infections across age groups than has previously been detected through traditional passive surveillance.