Dengue, a mosquito-borne tropical disease, has recently seen a significant surge in some states in India, such as Uttar Pradesh, West Bengal, and Tamil Nadu. This feverish illness can manifest with varying degrees of symptoms, from being asymptomatic to severe. The primary transmitter is the Aedes mosquito, particularly Aedes aegypti, which is also responsible for spreading chikungunya and Zika infection. The dengue virus consists of four closely related but distinct serotypes: DEN-1, DEN-2, DEN-3, and DEN-4.
Understanding Dengue
Dengue fever is an illness caused by any one of the four closely related virus serotypes. The primary symptoms are sudden high fever, severe headaches, pain behind the eyes, and substantial bone, joint, and muscle pain. Though the disease is self-limiting, severe cases require medical supervision and support.
The Dengue Vaccine
The dengue vaccine, CYD-TDV, or Dengvaxia, was approved by the US Food & Drug Administration in 2019. It is a live, attenuated dengue virus administered to individuals aged 9 to 16 who have had a laboratory-confirmed previous dengue infection and live in endemic areas.
In India, researchers at the National Centre for Biological Sciences collaborated with nine other institutions to develop the country’s first and only DNA vaccine candidate for dengue fever. Preliminary trials on mice showed the candidate generated a robust immune response and improved survival rates after exposure to the disease.
Controlling Dengue with Bacteria
The World Mosquito Program’s researchers have found innovative ways to control dengue by using mosquitoes infected with Wolbachia bacteria. This approach lead to a 77% reduction in dengue incidence in Indonesia.
What is a DNA Vaccine?
A DNA vaccine uses a small piece of DNA coding for a specific antigen from a pathogen to stimulate an immune response. This DNA is injected directly into the body’s cells, instructing them to produce the antigen. The immune system identifies it as foreign and mounts an immune response against it. Thus immunity to the pathogen is developed.
ZyCoV-D, the world’s first DNA based vaccine for Covid-19, was also indigenously developed in India.
UPSC Civil Services Examination Questions on Dengue
The previous year’s UPSC Civil Services Examination included questions on dengue transmission and control methods. One question from 2017 asked whether the same mosquito that transmits dengue also transmits Zika virus disease in tropical regions. Another one from 2023 referenced the ‘Wolbachia method’, which is used for controlling viral diseases spread by mosquitoes.