The global incidence of dengue has notably increased in the last two decades, posing a substantial challenge to public health.
Dengue transmission is cyclical, with major outbreaks expected every 3 to 4 years.
Following a slight decrease in cases between 2020-2022 due to the COVID-19 pandemic and a lower reporting rate, there has been an observed increase in dengue cases globally in 2023. This increase is characterized by a significant rise in the number, scale, and simultaneous incidence of multiple outbreaks, spreading to regions previously unaffected by dengue.
Since the beginning of 2023, ongoing transmission, coupled with an unexpected surge in dengue cases, has resulted in nearly a historical peak of over five million cases and more than 5000 dengue-related deaths reported in over 80 countries/territories and across five WHO regions: Africa, Americas, Southeast Asia, Western Pacific, and Eastern Mediterranean globally (Figure 1).
Figure 1: Countries/territories/areas reporting autochthonous dengue cases (November 2022 – November 2023) * Based on the most recent data available (data should be interpreted considering differences in reporting rates and case definitions among regions).
Approximately 80% of these cases, or 4.1 million, have been reported in the Region of the Americas. Dengue is the most widespread arbovirus and causes the highest number of arboviral disease cases in the Region of the Americas, with cyclical epidemics recurring every 3 to 5 years. Additionally, outbreaks of autochthonous dengue have been reported in the WHO European Region. However, these figures are likely to underestimate the true burden, as the majority of primary infections are asymptomatic and dengue reporting is not mandatory in many countries.
Several factors are associated with the increasing risk of the spread of the dengue epidemic. These include the changing distribution of vectors (mainly Aedes aegypti and Aedes albopictus), especially in countries previously unaffected by dengue; the consequences of the El Niño phenomenon in 2023 and climate change, which will lead to higher temperatures and increased rainfall, humidity, among others; fragile health systems amid the COVID-19 pandemic, political and financial instabilities in countries facing complex humanitarian crises, and large population movements. These factors also challenge the response to the epidemic and the risk of further spread to other countries. The weakness of surveillance systems in many affected countries may have led to delays in reporting and response, and in identifying symptoms, contributing to an increase in severe dengue outcomes.
The WHO has assessed the risk as high globally, taking into account the increasing risk of transmission and the rise in cases and deaths.
Source: https://www.who.int/emergencies/disease-outbreak-news/item/2023-DON498
