\ Il Parco \ Study from ICGEB New Delhi reveals paradigm shift in understanding Dengue

Contrary to the widely held belief that Dengue is severe in Secondary infections, a new collaborative study from ICGEB New Delhi has found that a substantial number of primary dengue infections also carry severe disease conditions. 

Published in Nature Medicine this week, an analysis of severe dengue cases in a cohort of children in India has shown that more than half could be attributed to primary rather than secondary infection.

Over the past two decades, Dengue infections have greatly increased in India and India now has one of the largest number of dengue cases globally. With 4 serotypes of the dengue virus, typically, Dengue patients fall into two categories- one, those experiencing the infection for the first time, known as primary infections and those, who get re-infected after a previous exposure, known as secondary infections. Traditionally, the prevailing belief has been that only secondary infections pose significant risks, leading much of the research into vaccine development and treatment to focus on this group.

But now this widely held perception seems to loose its ground. A new study carried out in India and based on a wide sampling approach has shown that it is not just the secondary infections but the primary infections as well which can be severe and could jeopardise the life of the patients. This finding suggests a need to reevaluate our understanding of Dengue and the strategies employed to combat it.

Dr. Anmol Chandele, Group Leader of the ICGEB-Emory Vaccine Program, ICGEB New Delhi, India, in collaboration with Emory School of Medicine, Atlanta, GA, USA, the All India Institute Of Medical Sciences AIIMS, New Delhi, and St. John’s National Academy of Health Sciences, Bengaluru, India authored the paper on “Severe disease during both primary and secondary virus infections in pediatric populations.”

Dr. Chandele states: “Dengue virus infection is a huge public health problem in India. Many patients develop severe disease that can also be sometimes fatal. However, much of the ongoing vaccine intervention research is based on the currently widely held global belief that primary dengue infections are not usually dangerous and that the severe dengue disease is mainly due to secondary dengue infections.” She continues: “Our study questions this currently widely held belief and shows that primary infections constitute a substantial fraction of severe disease cases and fatalities.”

This finding has important implications for public health and in developing and implementing effective and safe vaccine strategies for controlling dengue. These findings are highly relevant not only in the Indian context but also on a global scale since dengue viruses continue spreading worldwide.

Italy is a striking example of the expansion of dengue as also evidenced by a recent study being published on which Dr. Alessandro Marcello, head of the ICGEB Molecular Virology laboratory operating in the Area Science Park in Trieste, Italy, collaborated. “During 2023,” he tells us, “In Italy we had the highest number of cases and autochthonous transmissions of dengue so far. Climate change, above all, but also the movement of people, are the biggest contributors to the circulation of dengue in new areas. The study by our Indian colleagues shows us the need to protect our population also from the first encounter with the virus.”

The Chandele lab studies human immunology of infectious diseases, vaccine research and therapeutics. The ICGEB-Emory Vaccine program is a unique partnership established to facilitate international collaborations in vaccine research for tackling diseases of public health importance in developing countries.