Health & Medicine, India (Commonwealth Union) – Dengue virus is a mosquito-borne viral disease that affects millions of people worldwide. It is transmitted by the Aedes mosquito, which is commonly found in tropical and subtropical regions. Dengue fever can cause a wide range of symptoms, from mild fever to severe hemorrhagic fever, which can be fatal.
The Dengue virus belongs to the Flavivirus family and has four distinct serotypes, known as DEN-1, DEN-2, DEN-3, and DEN-4. All four serotypes can cause dengue fever, and infection with one serotype does not provide immunity to the other serotypes.
Multi-institutional research on dengue that was led by scientists at the Indian Institute of Science (IISc) have demonstrated the way the virus that brings about the condition has evolved to a large extent in the past few decades across the Indian subcontinent.
Researchers indicated that dengue cases have steadily risen in the last 50 years, mainly in the South-East Asian counties.
“We were trying to understand how different the Indian variants are, and we found that they are very different from the original strains used to develop the vaccines,” added Rahul Roy, an Associate Professor at the Department of Chemical Engineering (CE), IISc, as well as corresponding author of the findings that appeared in PLoS Pathogens. Associate Professor Roy along with collaborators assessed all available (408) genetic sequences for Indian dengue strains of infected patients gathered during the years of 1956 and 2018 by others together with the team themselves.
Associate Professor Roy further indicated that with the application of computational analysis, researchers evaluated the way much of every one of these serotypes changed paths from its ancestral sequence, for each other, as well as its other sequences from across the world.
Dengue fever typically begins with sudden onset of high fever, headache, muscle and joint pains, and a rash that appears two to five days after the onset of fever. The rash usually starts on the face and spreads to the rest of the body. Other symptoms may include nausea, vomiting, and diarrhea. In some cases, the symptoms can progress to severe dengue fever, which can cause bleeding, low blood pressure, and organ failure.
There is no specific treatment for dengue fever, and the disease is mainly managed by supportive care. This includes rest, fluids to prevent dehydration, and medication to relieve fever and pain. In severe cases, hospitalization may be necessary to monitor fluid levels and provide blood transfusions or other treatments.
Scientists further indicated that right up to 2012, the dominant strains in India had been Dengue 1 and 3. However in the recent years, Dengue 2 had seen greater dominance across India, while Dengue 4, classified as least infectious previously is currently forming a niche in South India. The researchers wanted to explore the factors deciding the strain that has dominance. A possibility may be Antibody Dependent Enhancement (ADE), according to Suraj Jagtap, PhD student from CE as well as the 1st author of the study.
ADE is a phenomenon that occurs when antibodies produced by the immune system in response to a virus actually enhance the virus’s ability to enter and infect cells. This can lead to more severe symptoms and a higher risk of complications.
Jagtap further elaborated that at certain times, individuals may be infected 1st with 1 serotype which is followed by the formation of a secondary infection with a different serotype, which can bring about symptom’s greater intensity. Researchers held the view that if the 2nd serotype has similarities to the 1st, the antibodies in the blood of the host formed following the 1st infection bind with the new serotype and the macrophages. This closeness permits the newcomer to cause macrophages infections, leading to more severe infection. “We knew that ADE enhances severity, [but] we wanted to know if that can also change the evolution of dengue virus,” said Jagtap.
