During the EPI-WIN webinar: Managing Dengue: a rapidly expanding epidemic, held in August, experts from around the world highlighted that about half of the global population is now at risk of dengue, with an estimated 100–400 million infections occurring each year.
“The incidence has increased nearly eightfold since 2000,” said Dr. Raman Velayudhan, head of the Veterinary Public Health Unit, Vector Control, Environment and Neglected Tropical Diseases at the World Health Organization (WHO), at the opening of the webinar. Before 1970, the disease’s vector mosquito was present in only half a dozen countries, he added, but is now found in over 130 countries.
Situation in the Americas
In the Americas, dengue is primarily transmitted by the Aedes aegypti mosquito, and the disease is endemic in many countries. Outbreaks tend to be cyclical every 3 to 5 years, following seasonal patterns corresponding to the warm and rainy months when mosquitoes breed.
In 2023, however, the Americas recorded a sharp increase in dengue cases. More than 3 million new infections have been reported so far, surpassing the numbers from 2019 – the year with the highest recorded incidence of the disease in the region, with 3.1 million cases, including 28,203 severe cases and 1,823 deaths.
The majority of cases – over 2.6 million – are recorded in the southern cone, with Brazil accounting for 80%. But unusually high transmission has also been observed in other areas of the continent, including the Andean region, with over 400,000 cases and a higher case fatality rate.
In March and June of this year, the Pan American Health Organization (PAHO) issued recommendations to help countries address the increase.
“Urbanization and climate change have had a huge impact on the spread of dengue,” said Velayudhan during the webinar. The movement and crowding of people in urban areas have helped spread the vector, he added, but disruptions caused by COVID-19 have also impacted mosquito control measures and case reporting.
“Post-COVID, we need to realign programs to be more integrated and ensure that health systems can manage,” said Velayudhan. “We must implement the lessons learned from the pandemic, such as in diagnosis and use of PCR testing, enhanced surveillance, good communication, and community engagement.”
Community Engagement for Effective Vector Control
There is no specific treatment for dengue, and prevention relies on vector control. Measures to contain mosquitoes include the use of chemicals, such as insecticides and repellents, and mechanical methods to remove breeding sites or provide a barrier, such as treated nets, screens on windows, and protective clothing.
Programs that use a combination of these methods can be effective, but involving communities to implement them is crucial for success, especially to remove or clean potential breeding habitats. Old and unused tires, for example, provide shade and a preferred dark space for Aedes mosquitoes to lay their eggs, which can withstand drought and develop only when they come into contact with water many months later.
Dengue is a viral infection that spreads from mosquitoes to people. Although most infections are asymptomatic or cause mild illness, the disease can occasionally become severe and even cause death. Symptoms range from mild to debilitating high fever, with intense headache, pain behind the eyes, muscle and joint pain, and rash. The disease can progress to severe dengue, characterized by shock, difficulty breathing, bleeding, and possible organ impairment.
Source: PAHO