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🧬 NEET Biology❓ Question

Malaria life cycle: which stage does the mosquito inject and where does fertilisation happen? Also pathogen-disease pairs

Mehak AroraDropper Sample

30 Sept 2026 · 1 min read

The chapter begins with WHO's definition: health is "a state of complete physical, mental and social well-being", not just the absence of disease or infirmity. (That line I know, it's also why I'm trying not to ignore my sleep.) Then the infectious diseases begin and I'm lost in the pathogen names.

Malaria is the one I want clarity on. My current understanding: the female Anopheles bites, injects something into the blood, which goes to the liver, then RBCs burst, and fever comes. The mosquito picks up another stage later. But which stage exactly is injected, what is released from RBCs that causes the fever, and where does the sexual stage happen?

Then there's the pathogen list: typhoid (Salmonella typhi), pneumonia (Streptococcus pneumoniae and Haemophilus influenzae), common cold (rhinoviruses), amoebiasis (Entamoeba histolytica), ascariasis (Ascaris), filariasis (Wuchereria), ringworm (fungi). Is this right? And how is typhoid confirmed?

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  • [+]Siddharth RaoDropperSample· 19d ago

    Malaria cycle in steps:

    1. Infected female Anopheles bites, injects sporozoites (the infectious stage) into your blood.
    2. Sporozoites go to the liver, multiply asexually in liver cells.
    3. They attack RBCs, multiply, and RBCs burst, releasing a toxic substance haemozoin, which causes chill and high fever recurring every 3-4 days.
    4. Some parasites form gametocytes inside RBCs.
    5. When another female Anopheles bites, it takes up gametocytes. Fertilisation and development happen in the mosquito's gut, then the sporozoites go to its salivary glands, ready for the next person.
  • [+]Farhan ShaikhDropperSample· 19d ago

    Just the species: Plasmodium vivax, P. malariae and P. falciparum. The most serious one is P. falciparum, it causes malignant malaria, and it can be fatal. The human is one host, mosquito is the other host (it's where the sexual stage happens). Mosquito isn't just a carrier, it's a host with a part of the life cycle in it.

  • [+]Nisha Verma12thSample· 19d ago

    the mosquito injects gametocytes when it bites, they go to the liver and that's how the infection starts. Gametocytes are the stage that infect humans. Then the fever is due to ... ok actually I'm not sure about the fever bit

  • [+]Zoya Khan12thSample· 19d ago

    Nisha, small mix-up. The mosquito injects sporozoites. Gametocytes are formed in human RBCs and are what the mosquito picks up. So direction: sporozoites go from mosquito to human, gametocytes go from human to mosquito. And Mehak, please do sleep, health is more than the absence of disease and it includes mental well-being, that's the WHO line you quoted.

    • [+]Mehak AroraDropperSample· 19d agoAuthor

      thanks zoya 🥺 ok, sporozoite in, gametocyte out, hopefully this stays. And I'm trying to sleep earlier, at least this week

    • [+]Nisha Verma12thSample· 19d ago

      yep reading it again, sporozoites obviously. Thanks zoya, and sorry mehak for the wrong half-answer

  • [+]Ishita GoyalDropperSample· 19d ago

    Pairs, as a one-glance list: typhoid = Salmonella typhi (confirmed by Widal test), pneumonia = Streptococcus pneumoniae + Haemophilus influenzae, common cold = rhinoviruses, amoebiasis = Entamoeba histolytica (protozoan), ascariasis = Ascaris (roundworm), filariasis = Wuchereria bancrofti / W. malayi (spread by the Culex mosquito), ringworm = Microsporum, Trichophyton, Epidermophyton (fungi).

    Also: typhoid and amoebiasis spread via contaminated food and water, common cold through droplets. Your list is right!

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