UPSC Prelims 2010·GS1·science-and-technology·science and technology

Widespread resistance of malarial parasite to drugs like chloroquine has prompted attempts to develop a malarial vaccine to combat malaria. Why is it difficult to develop an effective malaria vaccine?

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UPSC Civil Services preparation
Last updated 23 May 2026, 3:31 pm IST
  1. AMalaria is caused by several species of *Plasmodium*
  2. BMan does not develop immunity to malaria during natural infection
  3. CVaccines can be developed only against bacteria
  4. DMan is only an intermediate host and not the definitive hostCorrect

Explanation

The correct answer is D because of the biological complexity of the malaria parasite life cycle. In biological terms, the definitive host is the one where the parasite reaches maturity and undergoes sexual reproduction. For Plasmodium, the definitive host is the Anopheles mosquito, while humans are the intermediate hosts where only asexual reproduction occurs. This distinction is crucial because the parasite constantly changes its form and surface antigens as it moves through different stages in the human body, such as the liver stage and the red blood cell stage. This rapid transformation makes it extremely difficult for the human immune system to recognize and target the parasite consistently. Developing a vaccine that can effectively tackle these multiple, rapidly changing stages within an intermediate host is a significant scientific challenge.
science-and-technology: Widespread resistance of malarial parasite to drugs like chloroquine has prompted attempts to develop a malarial vaccine

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