Epidemiology of dengue and other arboviruses in a cohort of school children and their families in Yucatan, Mexico: Baseline and first year follow-up

Dengue is the most prevalent mosquito-borne viral disease of humans and is caused by the four serotypes of dengue virus. To estimate the incidence of dengue and other arboviruses, we analyzed the baseline and first year follow-up of a prospective school-based cohort study and their families in three cities in the state of Yucatan, Mexico. Through enhanced surveillance activities, acute febrile illnesses in the participants were detected and yearly blood samples were collected to evaluate dengue infection incidence. A Cox model was fitted to identify hazard ratios of arboviral infections in the first year of follow-up of the cohort. The incidence of dengue symptomatic infections observed during the first year of follow-up (2015–2016) was 3.5 cases per 1,000 person-years (95% CI: 1.9, 5.9). The incidence of dengue infections was 33.9 infections per 1,000 person-years (95% CI: 31.7, 48.0). The majority of dengue infections and seroconversions were observed in the younger age groups (≤ 14 years old). Other arboviruses were circulating in the state of Yucatan during the study period. The incidence of symptomatic chikungunya infections was 8.6 per 1,000 person-years (95% CI: 5.8, 12.3) and the incidence of symptomatic Zika infections was 2.3 per 1,000 person-years (95% CI: 0.9, 4.5). Our model shows that having a dengue infection during the first year of follow-up was significantly associated with being female, living in Ticul or Progreso, and being dengue naïve at baseline. Age was not significantly associated with the outcome, it was confounded by prior immunity to dengue that increases with age. This is the first report of a cohort in Latin America that provides incidence estimates of the three arboviruses co-circulating in all age groups. This study provides important information for understanding the epidemiology of dengue and other arboviruses and better informing public health policies.

登革热是人类感染最为普遍的虫媒病毒性疾病，由四种血清型登革病毒（Dengue virus）引发。为估算登革热及其他虫媒病毒（arbovirus）的发病率，我们对墨西哥尤卡坦州三座城市的一项前瞻性学校队列研究及其家属的基线数据与随访第一年数据展开了分析。通过强化监测活动，研究人员检测到受试者的急性发热病例，并采集年度血液样本以评估登革热感染发病率。本研究构建了Cox模型（Cox model），以确定队列随访第一年虫媒病毒感染的风险比。随访第一年（2015-2016年）观察到的有症状登革热感染发病率为3.5例/1000人年（95%置信区间CI：1.9, 5.9）；登革热总感染发病率为33.9例/1000人年（95% CI：31.7, 48.0）。大部分登革热感染与血清转换事件均发生于低龄组（≤14岁）。研究期间，尤卡坦州同时存在其他虫媒病毒的流行。其中，有症状基孔肯雅热（chikungunya）感染发病率为8.6例/1000人年（95% CI：5.8, 12.3），有症状寨卡病毒（Zika virus）感染发病率为2.3例/1000人年（95% CI：0.9, 4.5）。我们的模型显示，随访第一年发生登革热感染与女性性别、居住在蒂库尔（Ticul）或普罗格雷索（Progreso），以及基线时无登革热既往感染史（dengue naïve）显著相关。年龄与该研究结局无显著关联，其效应被随年龄增长而升高的登革热既往免疫水平所混淆。本研究是拉丁美洲首个针对全年龄组共循环的三种虫媒病毒开展发病率估算的队列研究报告。本研究为阐明登革热及其他虫媒病毒的流行病学特征提供了关键信息，也可为公共卫生政策制定提供更科学的决策依据。