RESUMO
The management of mosquito-borne diseases is a challenge in southern coastal Ecuador, where dengue is hyper-endemic and co-circulates with other arboviral diseases. Prior work in the region has explored social-ecological factors, dengue case data, and entomological indices. In this study, we bring together entomological and epidemiological data to describe links between social-ecological factors associated with risk of dengue transmission at the household level in Machala, Ecuador. Households surveys were conducted from 2014-2017 to assess the presence of adult Aedes aegypti (collected via aspiration) and to enumerate housing conditions, demographics, and mosquito prevention behaviors. Household-level dengue infection status was determined by laboratory diagnostics in 2014-2015. Bivariate analyses and multivariate logistic regression models were used to identify social-ecological variables associated with household presence of female Ae. aegypti and household dengue infection status, respectively. Aedes aegypti presence was associated with interruptions in water service and weekly trash collection, and household air conditioning was protective against mosquito presence. Presence of female Ae. aegypti was not associated with household dengue infections. We identified shaded patios and head of household employment status as risk factors for household-level dengue infection, while window screening in good condition was identified as protective against dengue infection. These findings add to our understanding of the systems of mosquito-borne disease transmission in Machala, and in the larger region of southern Ecuador, aiding in the development of improved vector surveillance efforts, and targeted interventions.
Assuntos
Dengue/etiologia , Aedes , Animais , Dengue/epidemiologia , Dengue/transmissão , Ecologia , Equador/epidemiologia , Características da Família , Feminino , Humanos , Modelos Logísticos , Mosquitos Vetores , Fatores de RiscoRESUMO
BACKGROUND: Dengue is a major emerging infectious disease, endemic throughout the tropics and subtropics, with approximately 2.5 billion people at risk globally. Active (AS) and passive surveillance (PS), when combined, can improve our understanding of dengue's complex disease dynamics to guide effective, targeted public health interventions. The objective of this study was to compare findings from the Ministry of Health (MoH) PS to a prospective AS arbovirus research study in Machala, Ecuador in 2014 and 2015. METHODS: Dengue cases in the PS system were compared to laboratory confirmed acute dengue illness cases that entered the AS study during the study period. Variables of interest included age class and sex. Outbreak detection curves by epidemiologic week, overall cumulative incidence and age-specific incidence proportions were calculated. Descriptive statistics were tabulated for all variables of interest. Chi-square tests were performed to compare demographic characteristics between the AS and PS data sets in 2014 and 2015. RESULTS: 177 and 245 cases were identified from 1/1/2014 to 12/31/2015 by PS and AS, respectively; nine cases appeared in both systems. AS identified a greater number of laboratory-confirmed cases in 2014, accounting for more than 60% of dengue cases in the study area. In 2015, the opposite trend was observed with PS identifying 60% of the dengue cases in the study area. Peak transmission time in laboratory confirmed dengue illness, as noted by AS and PS was similar in 2014, whereas earlier detection (7 weeks) was observed by AS in 2015. Younger patients were more frequently identified by PS, while older patients were identified more frequently by AS. The cumulative incidence proportion for laboratory confirmed dengue illness reported via PS to the MoH was 4.12 cases per 10,000 residents in 2014, and 2.21 cases per 10,000 residents in 2015. CONCLUSIONS: Each surveillance system captured distinct demographic subgroups within the Machala population, possibly due to differences in healthcare seeking behaviors, access to care, emerging threats of other viruses transmitted by the same mosquito vector and/or differences in clinical presentation. Integrating AS with pre-existing PS can aid in identifying additional cases in previously underdiagnosed subpopulations, improving our understanding of disease dynamics, and facilitating the implementation of timely public health interventions.
Assuntos
Dengue/epidemiologia , Surtos de Doenças/estatística & dados numéricos , Vigilância em Saúde Pública/métodos , Vigilância de Evento Sentinela , Adulto , Animais , Distribuição de Qui-Quadrado , Equador/epidemiologia , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Mosquitos Vetores , Estudos Prospectivos , Saúde Pública/estatística & dados numéricos , Adulto JovemRESUMO
Dengue viruses (DENV) pose a significant and increasing threat to human health across broad regions of the globe. Currently, prevention, control, and treatment strategies are limited. Promising interventions are on the horizon, including multiple vaccine candidates under development and a renewed and innovative focus on controlling the vector, Aedes aegypti. However, significant gaps persist in our understanding of the similarities and differences in DENV epidemiology across regions of potential implementation and evaluation. In this manuscript, we highlight and compare findings from two analogous cluster-based studies for DENV transmission and pathogenesis conducted in Thailand and Ecuador to identify key features and questions for further pursuit. Despite a remarkably similar incidence of DENV infection among enrolled neighborhood contacts at the two sites, we note a higher occurrence of secondary infection and severe illness in Thailand compared to Ecuador. A higher force of infection in Thailand, defined as the incidence of infection among susceptible individuals, is suggested by the higher number of captured Aedes mosquitoes per household, the increasing proportion of asymptomatic infections with advancing age, and the high proportion of infections identified as secondary-type infections by serology. These observations should be confirmed in long-term, parallel prospective cohort studies conducted across regions, which would advantageously permit characterization of baseline immune status (susceptibility) and contemporaneous assessment of risks and risk factors for dengue illness.
Assuntos
Vírus da Dengue , Dengue , Animais , Dengue/epidemiologia , Equador/epidemiologia , Humanos , Mosquitos Vetores , Estudos Prospectivos , Tailândia/epidemiologiaRESUMO
BACKGROUND: In recent years, Ecuador and other South American countries have experienced an increase in arboviral diseases. A rise in dengue infections was followed by introductions of chikungunya and Zika, two viruses never before seen in many of these areas. Furthermore, the latest socioeconomic and political instability in Venezuela and the mass migration of its population into the neighboring countries has given rise to concerns of infectious disease spillover and escalation of arboviral spread in the region. RESULTS: We performed phylogeographic analyses of dengue (DENV) and chikungunya (CHIKV) virus genomes sampled from a surveillance site in Ecuador in 2014-2015, along with genomes from the surrounding countries. Our results revealed at least two introductions of DENV, in 2011 and late 2013, that initially originated from Venezuela and/or Colombia. The introductions were subsequent to increases in the influx of Venezuelan and Colombian citizens into Ecuador, which in 2013 were 343% and 214% higher than in 2009, respectively. However, we show that Venezuela has historically been an important source of DENV dispersal in this region, even before the massive exodus of its population, suggesting already established paths of viral distribution. Like DENV, CHIKV was introduced into Ecuador at multiple time points in 2013-2014, but unlike DENV, these introductions were associated with the Caribbean. Our findings indicated no direct CHIKV connection between Ecuador, Colombia, and Venezuela as of 2015, suggesting that CHIKV was, at this point, not following the paths of DENV spread. CONCLUSION: Our results reveal that Ecuador is vulnerable to arbovirus import from many geographic locations, emphasizing the need of continued surveillance and more diversified prevention strategies. Importantly, increase in human movement along established paths of viral dissemination, combined with regional outbreaks and epidemics, may facilitate viral spread and lead to novel virus introductions. Thus, strengthening infectious disease surveillance and control along migration routes and improving access to healthcare for the vulnerable populations is of utmost importance.
Assuntos
Febre de Chikungunya/epidemiologia , Vírus Chikungunya/classificação , Vírus Chikungunya/genética , Vírus da Dengue/classificação , Vírus da Dengue/genética , Dengue/epidemiologia , Emigração e Imigração/estatística & dados numéricos , Febre de Chikungunya/transmissão , Febre de Chikungunya/virologia , Vírus Chikungunya/isolamento & purificação , Colômbia/epidemiologia , Dengue/transmissão , Dengue/virologia , Vírus da Dengue/isolamento & purificação , Surtos de Doenças , Equador/epidemiologia , Emigração e Imigração/tendências , Genoma Viral , Genótipo , Humanos , Mutação de Sentido Incorreto/fisiologia , Fenótipo , Filogeografia , Análise de Sequência de DNA , América do Sul/epidemiologia , Venezuela/epidemiologia , Zika virus/isolamento & purificação , Infecção por Zika virus/epidemiologia , Infecção por Zika virus/transmissão , Infecção por Zika virus/virologiaRESUMO
BACKGROUND: Micronutrients are known to modulate host immunity, and there is limited literature on this association in the context of dengue virus infection (DENV). METHODS: Using a nested case-control design in a surveillance program, we measured the following: anthropometry; nutritional biomarkers including serum ferritin, soluble transferrin receptor, retinol-binding protein (RBP), 25-hydroxy vitamin D, folate, and vitamin B12; and a panel of immune response markers. We then compared these measures across 4 illness categories: healthy control, nonfebrile DENV, other febrile illness (OFI), and apparent DENV using multivariate polytomous logistic regression models. RESULTS: Among 142 participants, serum ferritin (ng/mL) was associated with apparent DENV compared to healthy controls (odds ratio [OR], 2.66; confidence interval [CI], 1.53-4.62; P = .001), and RBP concentrations (µmol/L) were associated with apparent DENV (OR, 0.03; CI, 0.00-0.30; P = .003) and OFI (OR, 0.02; CI, 0.00-0.24; P = .003). In a subset of 71 participants, interleukin-15 levels (median fluorescent intensity) were positively associated with apparent DENV (OR, 1.09; CI, 1.03-1.14; P = .001) and negatively associated with nonfebrile DENV (OR, 0.89; CI, 0.80-0.99; P = .03) compared to healthy controls. CONCLUSIONS: After adjusting for the acute-phase response, serum ferritin and RBP concentrations were associated with apparent DENV and may represent biomarkers of clinical importance in the context of dengue illness.
Assuntos
Dengue/sangue , Dengue/imunologia , Interleucina-15/sangue , Vigilância da População , Adolescente , Biomarcadores/sangue , Índice de Massa Corporal , Tamanho Corporal , Proteína C-Reativa/metabolismo , Estudos de Casos e Controles , Equador , Feminino , Ferritinas/sangue , Febre/sangue , Febre/virologia , Humanos , Masculino , Micronutrientes , Estado Nutricional , Orosomucoide/metabolismo , Proteínas Plasmáticas de Ligação ao Retinol/metabolismo , Vitamina D/sangue , Adulto JovemRESUMO
Tick-borne diseases (TBDs) are a growing public health threat and are increasingly identified as the cause of undifferentiated febrile illness. There is a significant gap in our understanding of ticks and their associated pathogens in Ecuador. An arboviral surveillance study allowed us to explore potential exposure to TBDs in febrile subjects. We tested plasma samples from 222 febrile subjects for spotted fever group rickettsial (SFGR) antibodies from southern coastal Ecuador in 2014-2015 via ELISA. Fifty-five (25%) subjects had evidence of anti-SFRG IgG or IgM antibodies. Although attempts to detect Rickettsia species in plasma by polymerase chain reaction were unsuccessful, these preliminary data suggest the possibility of endemic SFGR transmission in Ecuador. To better understand the burden and entomological risk for TBDs in Ecuador, future studies should expand TBD surveillance in humans, document common human-biting ticks, and measure pathogen carriage rates in questing ticks.
Assuntos
Anticorpos Antibacterianos/sangue , Infecções por Arbovirus/imunologia , Coinfecção/microbiologia , Coinfecção/virologia , Rickettsiose do Grupo da Febre Maculosa/imunologia , Adolescente , Adulto , Infecções por Arbovirus/epidemiologia , Criança , Coinfecção/epidemiologia , Equador/epidemiologia , Feminino , Febre , Humanos , Imunoglobulina M/sangue , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Rickettsiose do Grupo da Febre Maculosa/epidemiologia , Adulto JovemRESUMO
Mass migration from Venezuela has increased malaria resurgence risk across South America. During 2018, migrants from Venezuela constituted 96% of imported malaria cases along the Ecuador-Peru border. Plasmodium vivax predominated (96%). Autochthonous malaria cases emerged in areas previously malaria-free. Heightened malaria control and a response to this humanitarian crisis are imperative.
Assuntos
Doenças Transmissíveis Emergentes/epidemiologia , Malária/epidemiologia , Sistemas Políticos , Meio Social , Doenças Transmissíveis Emergentes/história , Equador/epidemiologia , Geografia Médica , História do Século XXI , Humanos , Malária/história , Peru/epidemiologia , Venezuela/epidemiologiaRESUMO
Occurrence of Chagas disease and arbovirus coinfections is unknown, despite the vast co-endemic areas throughout the Americas. This study examined the proportion of individuals positive for Trypanosoma cruzi and coinfections with dengue, chikungunya, and Zika viruses in Machala, Ecuador (January 2014-December 2015). Chagas seropositivity was evaluated with five commercially available assays. Dengue infections were identified by nonstructural protein 1 rapid test and enzyme linked immunosorbent assay (ELISA), immunoglobulin M ELISA, and reverse transcription PCR (RT-PCR); chikungunya and Zika infections were identified by RT-PCR. Of 658 individuals, six were positive for T. cruzi (0.91%), including one T. cruzi/dengue coinfection and one T. cruzi/chikungunya/dengue coinfection. The clinical manifestations of coinfected individuals corresponded to severe dengue and dengue with warning signs, respectively. We observed discrepant results by using the Hemagen Chagas kit and the rapid test Chagas Detect Plus (false positives: 3.9% and 15.4%), highlighting the need to assess diagnostic assays in geographic regions with distinct taxonomic units of T. cruzi.
Assuntos
Antígenos Virais/sangue , Doença de Chagas/epidemiologia , Febre de Chikungunya/epidemiologia , Dengue/epidemiologia , RNA Viral/sangue , Infecção por Zika virus/epidemiologia , Adulto , Idoso , Doença de Chagas/diagnóstico , Doença de Chagas/parasitologia , Febre de Chikungunya/diagnóstico , Febre de Chikungunya/parasitologia , Vírus Chikungunya/genética , Vírus Chikungunya/imunologia , Vírus Chikungunya/isolamento & purificação , Coinfecção , Dengue/diagnóstico , Dengue/parasitologia , Vírus da Dengue/genética , Vírus da Dengue/imunologia , Vírus da Dengue/isolamento & purificação , Equador/epidemiologia , Ensaio de Imunoadsorção Enzimática/normas , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase Via Transcriptase Reversa/normas , Trypanosoma cruzi/imunologia , Trypanosoma cruzi/isolamento & purificação , Zika virus/genética , Zika virus/imunologia , Zika virus/isolamento & purificação , Infecção por Zika virus/diagnóstico , Infecção por Zika virus/parasitologiaRESUMO
Here, we report the findings from the first 2 years (2014-2015) of an arbovirus surveillance study conducted in Machala, Ecuador, a dengue-endemic region. Patients with suspected dengue virus (DENV) infections (index cases, N = 324) were referred from five Ministry of Health clinical sites. A subset of DENV-positive index cases (N = 44) were selected, and individuals from the index household and four neighboring homes within 200 m were recruited (N = 400). Individuals who entered the study, other than the index cases, are referred to as associates. In 2014, 70.9% of index cases and 35.6% of associates had acute or recent DENV infections. In 2015, 28.3% of index cases and 12.8% of associates had acute or recent DENV infections. For every DENV infection captured by passive surveillance, we detected an additional three acute or recent DENV infections in associates. Of associates with acute DENV infections, 68% reported dengue-like symptoms, with the highest prevalence of symptomatic acute infections in children aged less than 10 years. The first chikungunya virus (CHIKV) infections were detected on epidemiological week 12 in 2015; 43.1% of index cases and 3.5% of associates had acute CHIKV infections. No Zika virus 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, indicating the presence of viral flow between Ecuador and surrounding countries. Enhanced surveillance studies, such as this, provide high-resolution data on symptomatic and inapparent infections across the population.
Assuntos
Febre de Chikungunya/epidemiologia , Febre de Chikungunya/virologia , Dengue/epidemiologia , Dengue/virologia , Adolescente , Adulto , Idoso , Vírus Chikungunya/genética , Criança , Pré-Escolar , Vírus da Dengue/genética , Equador/epidemiologia , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Filogenia , Vigilância da População , Prevalência , Adulto JovemRESUMO
BACKGROUND: In Ecuador, dengue virus (DENV) infections transmitted by the Aedes aegypti mosquito are among the greatest public health concerns in urban coastal communities. Community- and household-level vector control is the principal means of controlling disease outbreaks. This study aimed to assess the impact of knowledge, attitudes, and practices (KAPs) and social-ecological factors on the presence or absence of DENV infections in the household. METHODS: In 2014 and 2015, individuals with DENV infections from sentinel clinics in Machala, Ecuador, were invited to participate in the study, as well as members of their household and members of four neighboring households located within 200 meters. We conducted diagnostic testing for DENV on all study participants; we surveyed heads of households (HOHs) regarding demographics, housing conditions and KAPs. We compared KAPs and social-ecological factors between households with (n = 139) versus without (n = 80) DENV infections, using bivariate analyses and multivariate logistic regression models with and without interactions. RESULTS: Significant risk factors in multivariate models included proximity to abandoned properties, interruptions in piped water, and shaded patios (p<0.05). Significant protective factors included the use of mosquito bed nets, fumigation inside the home, and piped water inside the home (p<0.05). In bivariate analyses (but not multivariate modeling), DENV infections were positively associated with HOHs who were male, employed, and of younger age than households without infections (p<0.05). DENV infections were not associated with knowledge, attitude, or reported barriers to prevention activities. DISCUSSION: Specific actions that can be considered to decrease the risk of DENV infections in the household include targeting vector control in highly shaded properties, fumigating inside the home, and use of mosquito bed nets. Community-level interventions include cleanup of abandoned properties, daily garbage collection, and reliable piped water inside houses. These findings can inform interventions to reduce the risk of other diseases transmitted by the Ae. aegypti mosquito, such as chikungunya and Zika fever.