Question

Which stage of a malarial parasite escapes digestion in the stomach of a mosquito?
A) Gametocytes
B) Trophozoite
C) Merozoites
D) Sporozoites

Answer 1

Hint: Two hosts are involved in the malaria parasite's life cycle. A malaria-infected female Anopheles mosquito inoculates sporozoites into the human host during a blood meal. Sporozoites infect liver cells, grow into schizonts, and then burst, releasing merozoites.

Complete answer:
When the parasite infects an animal, it attacks in three stages: initially, it affects liver cells, then blood cells, and ultimately, it generates gametes that mosquitoes can transmit. The majority of therapies focus on parasites in the blood stage, which causes the symptoms of malaria—fever, vomiting, and coma.
Malaria infection starts when a female Anopheles mosquito bites a human, injecting Plasmodium parasites into the bloodstream in the form of sporozoites. The sporozoites enter the human liver soon.

Over the next 7 to 10 days, the sporozoites grow asexually in the liver cells, generating no symptoms.
The parasites, which are released from the liver cells in vesicles, travel via the heart and into the lungs, where they lodge within lung capillaries, in an animal model. The vesicles gradually disintegrate, allowing the merozoites to go to the blood stage of development.

Merozoites infiltrate red blood cells (erythrocytes) in the bloodstream and grow until the cells explode. After that, they infiltrate additional erythrocytes. Each time parasites break loose and invade blood cells, the cycle repeats, generating fever.

Some infected blood cells break the asexual multiplication cycle. Instead of reproducing, the merozoites in these cells mature into gametocytes, which circulate in the bloodstream as sexual forms of the parasite.

When a mosquito bites an infected person, the gametocytes are ingested, and the gametocytes develop into mature sex cells known as gametes.

Malaria parasites have two stages of life: sexual in mosquitos and asexual in humans. When mosquitoes bite, the parasite is injected into human tissues. They poured into the bloodstream as merozoites and lysed the RBCs before developing into trophozoites. In the circulation, these trophozoites create gametocytes. When mosquitoes bite again, they enter the mosquito's stomach via blood and fertilise to form a zygote.
Therefore the correct answer is option ‘A’.

Note: Malaria symptoms usually appear 10 to 4 weeks after the infection has occurred. Symptoms may not appear for several months in some circumstances. Malaria parasites can enter the body, but they will remain latent for a long time.