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DENGUE SURGE IN LATIN AMERICA

4th May, 2024

DENGUE SURGE IN LATIN AMERICA

Source: HindustanTimes

Disclaimer: Copyright infringement not intended.

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)