DENGUE VIRUS
1. Context
Dengue has expanded its footprint across the country over the last two decades due to climate change, increased urbanization with a temperature-controlled environment, and rapid urbanization leading to a shortage of utilities such as running water.
2. What is Dengue?
- The dengue virus is a member of the Flaviviridae family and is responsible for causing dengue fever, a significant global health concern.
- This virus is transmitted primarily through the bite of infected Aedes mosquitoes, with Aedes aegypti being the primary vector.
- Dengue infections can range from asymptomatic or mild cases to severe forms, including dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS), which can be life-threatening.
Key Characteristics of the Dengue Virus:
- Serotypes: There are four distinct serotypes of the dengue virus: DEN-1, DEN-2, DEN-3, and DEN-4. Each serotype can cause the full spectrum of dengue disease, but subsequent infections with different serotypes increase the risk of severe disease.
- Genome: The dengue virus has a single-stranded RNA genome that encodes for three structural proteins (capsid, precursor membrane, and envelope) and seven non-structural proteins.
- Replication: The virus replicates in both mosquitoes and humans. In mosquitoes, it infects midgut cells and salivary glands, facilitating transmission. In humans, it replicates in various tissues, including skin, lymph nodes, and spleen.
Transmission: Aedes mosquitoes are the primary vectors responsible for transmitting the dengue virus. When an infected mosquito bites a person, the virus is introduced into the person's bloodstream. Once inside the human body, the virus replicates and spreads, leading to the onset of dengue symptoms.
3. Which virus causes dengue?
- The virus responsible for causing dengue is known as the dengue virus.
- It belongs to the Flaviviridae family and is classified into four distinct serotypes: DEN-1, DEN-2, DEN-3, and DEN-4.
- These serotypes are closely related but distinct variations of the dengue virus.
- Infection with one serotype provides lifelong immunity to that specific serotype but only temporary immunity to the others.
- Subsequent infections with different serotypes increase the risk of severe dengue, as the immune response can sometimes enhance the virus's replication, leading to more severe symptoms.
4. Why it is spreading in India
The spread of dengue in India can be attributed to a combination of factors, including environmental, climatic, socio-economic, and public health aspects. Some of the key reasons for the spread of dengue in India are:
- Climate and Environment: Aedes mosquitoes, primarily Aedes aegypti, which are responsible for transmitting the dengue virus, thrive in warm and humid environments. India's tropical and subtropical climate provides favorable conditions for the breeding and survival of these mosquitoes.
- Urbanization and Population Growth: Rapid urbanization and population growth have led to increased construction and improper waste management, creating more breeding sites for mosquitoes. Urban areas with crowded populations and inadequate sanitation can facilitate the transmission of dengue.
- Water Storage Practices: Aedes mosquitoes prefer to breed in clean, stagnant water. Improper water storage practices, such as uncovered containers or discarded tires, provide breeding sites for these mosquitoes. Many communities lack proper waste disposal mechanisms, contributing to mosquito breeding.
- Lack of Vector Control: Inadequate vector control measures, including limited use of insecticides, mosquito repellents, and larval control methods, contribute to the increased presence of Aedes mosquitoes in residential areas.
- Travel and Migration: The movement of people, including tourists and migrant workers, can contribute to the spread of dengue from one region to another. Infected individuals can carry the virus and introduce it to new areas where susceptible mosquito vectors are present.
5. Is there any vaccine for dengue in India?
- The first dengue vaccine approved for use in the country is called "Dengvaxia," which is manufactured by Sanofi Pasteur. Dengvaxia is a tetravalent vaccine, meaning it provides protection against all four serotypes of the dengue virus (DEN-1, DEN-2, DEN-3, and DEN-4).
- Dengvaxia is indicated for individuals aged 9 to 45 years who have a history of laboratory-confirmed previous dengue infection. This is because the vaccine's safety profile is better established in individuals who have been previously exposed to the virus. The vaccine helps to reduce the risk of severe dengue disease in those who have had a prior infection.
- It's important to note that Dengvaxia is not recommended for individuals who have not been previously infected with the dengue virus, as there is evidence suggesting that the vaccine can lead to more severe disease in individuals without prior exposure.
- The availability and usage of the dengue vaccine may vary across different regions and healthcare settings within India. As with any vaccine, its administration should be carried out under the guidance of healthcare professionals, taking into consideration individual medical histories and risk factors.
6. What do you understand by the DNA Vaccines?
- DNA vaccines, a cutting-edge innovation in the field of immunization, offer a novel way to stimulate the immune system's response against pathogens.
- Unlike traditional vaccines that use weakened or inactivated pathogens, DNA vaccines harness the power of genetic material to trigger immunity.
- They hold immense potential for combating a range of diseases, from infectious diseases to cancers, by leveraging the body's own cellular machinery.
7. Indian Council of Medical Research
- The Indian Council of Medical Research (ICMR) is the apex body in India responsible for coordinating and promoting biomedical research in the country.
- Established in 1911, it operates under the Department of Health Research, Ministry of Health and Family Welfare, Government of India.
- The ICMR plays a crucial role in shaping the health research landscape, addressing health challenges, and advancing scientific knowledge.
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For Prelims: Dengue Virus, Indian Council of Medical Research (ICMR), dengue hemorrhagic fever (DHF), and dengue shock syndrome (DSS).
For Mains: 1. Analyze the Role of Climate Change in the Increasing Incidence of Dengue Virus Infections and its Implications for Public Health. (250 words).
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Source: The Indian Express
