Institute of Infection and Immunity, St George's University of London, London, UK
International University of Ecuador, Quito, Ecuador.
BMJ Open. 2020 Oct 16;10(10):e040735. doi: 10.1136/bmjopen-2020-040735.
There are few population-based estimates for prevalence of past exposure to dengue and chikungunya viruses despite common epidemiological features. Here, we have developed a novel statistical method to study patterns of age-dependent prevalence of immunity in a population following exposures to two viruses which share similar epidemiological features including mode of transmission and induction of long-lasting immunity. This statistical technique accounted for sociodemographic characteristics associated with individuals and households.
The data consist of a representative sample from an ongoing longitudinal birth cohort set-up in a tropical district in coastal Ecuador (Esmeraldas).
We collected data and blood samples from 319 individuals belonging to 152 households following epidemics of the infections in 2015 in Latin America.
Plasma was tested for the presence of specific IgG antibodies to dengue and chikungunya viruses by commercial ELISA and defined a bivariate binary outcome indicating individuals' past exposure status to dengue and chikungunya (ie, presence/absence of IgG antibodies to dengue or chikungunya or both).
Dengue seroprevalence increased rapidly with age reaching 97% (95% credible interval (CrI): 93%-99%) by 60 years. Chikungunya seroprevalence peaked at 42% (95% CrI: 18%-66%) around 9 years of age and averaged 27% (95% CrI: 8.7%-51.6%) for all ages. Rural areas were more likely to be associated with dengue-only exposure while urban areas and shorter distance to the nearest household were associated with exposures to both. Women living in urban settings were more likely to be chikungunya seropositive while rural men were more likely to be dengue seropositive.
Dengue seroprevalence was strongly age dependent consistent with endemic exposure while that of chikungunya peaked in childhood consistent with the recent emergence of the virus in the study area. Our findings will inform control strategies for the two arboviruses in Ecuador including recommendations by the WHO on dengue vaccination.
尽管登革热和基孔肯雅热病毒具有共同的流行病学特征，但针对这两种病毒过去暴露情况的流行率，目前仅有少数基于人群的估计数据。在此，我们开发了一种新的统计方法，用于研究人群中对两种具有相似流行病学特征（包括传播方式和诱导长期免疫）的病毒的暴露后，免疫随年龄变化的模式。该统计技术考虑了与个体和家庭相关的社会人口学特征。
数据来自厄瓜多尔沿海埃斯梅拉达斯热带地区正在进行的纵向出生队列的代表性样本。
我们在拉丁美洲 2015 年感染流行期间，从属于 152 个家庭的 319 名个体中收集了数据和血液样本。
通过商业 ELISA 检测血浆中针对登革热和基孔肯雅热病毒的特异性 IgG 抗体，定义了一个二元二项结果，表明个体过去曾暴露于登革热和基孔肯雅热（即存在/不存在针对登革热或基孔肯雅热或两者的 IgG 抗体）。
登革热血清流行率随年龄迅速增加，到 60 岁时达到 97%（95%可信区间[CrI]：93%-99%）。基孔肯雅热血清流行率在 9 岁左右达到峰值 42%（95% CrI：18%-66%），所有年龄的平均流行率为 27%（95% CrI：8.7%-51.6%）。农村地区更可能与仅登革热暴露有关，而城市地区和与最近家庭的最短距离与两种病毒的暴露有关。居住在城市环境中的女性更有可能基孔肯雅热血清阳性，而农村男性更有可能登革热血清阳性。
登革热血清流行率与地方性暴露密切相关，呈年龄依赖性，而基孔肯雅热的流行率在儿童时期达到峰值，与该病毒在研究地区的新出现相一致。我们的研究结果将为厄瓜多尔的两种虫媒病毒提供控制策略，包括世界卫生组织对登革热疫苗接种的建议。
