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A new study by Indian researchers has found evidence suggesting that even the first time, or primary, Dengue infections can be fatal.challenging the prevailing understanding that only second or subsequent (secondary) infections resulted in serious or life-threatening situations.
The new idea was the result of collaborative work by researchers from institutions such as the International Center for Genetic Engineering and Biotechnology (ICGEB), based in Delhi; All India Institute of Medical Sciences (AIIMS), New Delhi; Christian Medical College, Vellore; and Emory University, in Atlanta, in the US state of Georgia; among others. His findings were recently published in the journal Nature Medicine.
The research involved the study of 619 children admitted to three different hospitals. Primary dengue infections were found to account for more than half of the total number of clinical cases (344 of 619), severe cases (112 of 202) and deaths (5 of 7). The findings could have important implications for dengue vaccine research and treatment.
“The results of this study mean that primary infections can no longer be ignored. “It also has global importance as the global spread of dengue viruses is expected to continue and more children and populations with no prior experience with dengue could eventually face the risk of dengue infection, severe illness and death,” said Dr. Anmol Chandele, associate professor at ICGEB, and one of the researchers involved in the study, told The Indian Express.
Dengue, a mosquito-borne viral disease, can cause a spectrum of clinical presentations, from mild fever to severe hemorrhagic fever and life-threatening dengue shock syndrome.
Dengue infections have increased sharply in India over the past two decades. Data from the central government’s National Center for Vector Borne Disease Control indicates that in the last three years there were more than 5.20 lakh dengue cases and 740 deaths. There were 1,93,245 cases and 346 deaths in 2021, 2,33,251 cases and 303 deaths in 2022, and 94,198 cases and 91 deaths in 2023.
Despite its global impact and ongoing efforts to identify a universally approved vaccine and effective therapies, the prevalence of dengue has increased dramatically since the 1970s, now affecting more than 130 countries and causing approximately 390 million infections and 100 million clinical cases per year.
Dengue infections are caused by four serotypes (four closely related viruses that attack the immune system in different ways) and studies have suggested that people can gain lifelong immunity against the serotype with which they were infected. However, there is evidence to show that immunity to one serotype could exponentially increase the likelihood of severe disease if later infected with another serotype.
Most of these studies come from Southeast Asia and South America, regions that have seen dengue infection long before India, which experienced its first outbreak in the 1960s and then saw sporadic cases in the following decades.
Only very recently has dengue transmission become constant, and a recent modeling study suggested that India itself has between 30 and 40 million infections a year and that India is the epicenter of dengue infections. What was not known is the proportion of primary versus secondary dengue infections and how it correlates with the severity of the disease.
In the latest study, researchers examined children with confirmed dengue associated with fever in three hospitals in different regions of India. Three tertiary care centers – St John’s Research Institute (SJRI), All India Institute of Medical Sciences (AIIMS) and Christian Medical College – participated in the study in which 619 children with confirmed dengue were studied between 2012 and 2018. “Our findings challenge the current widespread belief that severe dengue is predominantly associated with secondary infections and emphasizes the importance of developing vaccines or treatments to protect populations that have not suffered from dengue,” said Dr. Chandele.