Source: HindustanTimes

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Context

• Latin America and the Caribbean are experiencing a significant surge in dengue cases, with more than 5.9 million cases reported between January and April 2024, compared to 4.4 million in all of 2023.
• This surge is attributed to various factors, including soaring global temperatures, extreme weather events, rapid urbanization, and challenges in vaccine development

Details

Factors Contributing to Dengue Surge

• Climate Change:
  • Rising temperatures create ideal conditions for mosquito vectors to thrive, extending the mosquito season and increasing dengue transmission.
  • The region has warmed by an average of 0.2 degrees Celsius per decade over the past 30 years, leading to more frequent and intense extreme weather events.
• Extreme Weather Events:
  • Events like El Niño exacerbate temperature increases and disrupt weather patterns, leading to abnormal rainfall, storms, flooding, and rising sea levels.
  • These events create breeding grounds for mosquitoes, contributing to the proliferation of dengue vectors.
• Rapid Urbanization:
  • Urban areas, particularly shantytowns, provide ample breeding sites for mosquitoes due to standing water and poor waste management.
  • Lack of basic plumbing and waste collection services exacerbates mosquito proliferation, increasing the risk of dengue transmission.

Current Situation in Latin America

• Brazil:
  • Worst affected country, with over 4.2 million cases reported in 2024, resulting in more than 2,000 deaths.
  • Several states have declared a state of emergency, with field hospitals established to accommodate patients.
• Peru and Puerto Rico:
  • Both countries have declared a state of emergency in response to a spike in dengue cases.
  • Significant increases in suspected cases and deaths compared to previous years have been reported.
• Other Countries:
  • Central American countries, Mexico, Argentina, Uruguay, and Chile are also experiencing surges in dengue cases.
  • Some regions are witnessing outbreaks for the first time or after long periods of no transmission.

Dengue Vaccine Development

Challenges in Vaccine Development:

• Dengue virus has four distinct serotypes (DENV-1, DENV-2, DENV-3, and DENV-4), making vaccine development complex.
• Protection against one serotype can potentially increase susceptibility to severe disease upon subsequent infection with a different serotype.
• Developing a vaccine that provides broad and durable protection against all four serotypes is a significant challenge.

Existing Vaccines:

Qdenga (Takeda Pharmaceuticals):

• A Japanese-made vaccine that protects against all four dengue serotypes.
• Expensive: Costs about $115 per dose in Europe and $40 in Indonesia.
• Brazil negotiated a lower price ($19 per dose) for large-scale purchase and is using it to vaccinate its population.
• However, the available supply may only fully vaccinate a small fraction of Brazil's population due to limited availability.

Dengvaxia (Sanofi Pasteur):

• A French-manufactured vaccine approved for use in individuals aged 9 to 45 who have had a prior dengue infection.
• Provides partial protection against dengue but has limitations, including age restrictions and the requirement of prior infection.

Recent Developments:

New Dengue Vaccine by National Institutes of Health (NIH):

• Brazilian researchers announced promising results from a clinical trial of a new dengue vaccine developed by the NIH.
• The vaccine uses live, weakened forms of all four dengue virus serotypes, providing strong immunity against the disease.
• Licensed for development by Instituto Butantan in Brazil, the vaccine offers potential advantages over existing vaccines.
• While it may address some limitations of previous vaccines, it is not expected to be rolled out at a national scale in Brazil for at least a couple of years.

Serum Institute of India (SII):

• SII, the world's largest vaccine maker, is also developing a single-shot dengue vaccine based on NIH research.
• The vaccine aims to provide broad protection against all four dengue virus serotypes.
• Currently undergoing testing, the SII vaccine represents another potential breakthrough in dengue vaccine development.

Must Read Articles:

Dengue

Sources:

IndianExpress

PRACTICE QUESTION Q.  The record dengue surge in Latin America and the Caribbean is driven by a combination of factors, including climate change, extreme weather events, rapid urbanization, and challenges in vaccine development. Comment. (150 words)