Abstract
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.
Highlights
In this article we show that around 70% of the cohort population has prior immunity to dengue
Over the past 40 years, dengue virus incidence in human population has increased 30-fold and the geographic range of the virus expanding to new countries as increasing urbanization, global human travel and urban to rural migration enable opportunities for transmission [1, 2] Currently more than 40% of the human population worldwide is at risk of dengue infections, with approximately 390 million infections estimated to occur globally each year, of which 96 million have clinical manifestations of the virus [3]
Dengue virus (DENV) has four serotypes, each of them can be responsible for dengue epidemics and can be associated with severe disease depending on the sequence and time between infections, among other factors [4,5,6]
Summary
Over the past 40 years, dengue virus incidence in human population has increased 30-fold and the geographic range of the virus expanding to new countries as increasing urbanization, global human travel and urban to rural migration enable opportunities for transmission [1, 2] Currently more than 40% of the human population worldwide is at risk of dengue infections, with approximately 390 million infections estimated to occur globally each year, of which 96 million have clinical manifestations of the virus [3].Dengue virus (DENV) has four serotypes, each of them can be responsible for dengue epidemics and can be associated with severe disease depending on the sequence and time between infections, among other factors [4,5,6]. Over the past 40 years, dengue virus incidence in human population has increased 30-fold and the geographic range of the virus expanding to new countries as increasing urbanization, global human travel and urban to rural migration enable opportunities for transmission [1, 2] Currently more than 40% of the human population worldwide is at risk of dengue infections, with approximately 390 million infections estimated to occur globally each year, of which 96 million have clinical manifestations of the virus [3]. Surveillance systems based on the monitoring and notification of dengue symptomatic cases have low sensitivity and rarely detect low or sporadic transmission [11, 12]. Necessary steps to better understand dengue transmission in at-risk populations include strengthening passive surveillance systems by incorporating active surveillance methods (e.g., house-to-house visits, school absenteeism or self-identification of fever episodes) and improving the detection of inapparent infections to rectify the underreporting of unspecified febrile dengue infections
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