Question

Infective stage of plasmodium is
a. Trophozoite
b. Merozoite
c. Schizont
d. Sporozoite

Answer 1

Hint: The plasmodium is transferred by the bite of the female Anopheles mosquito. Other insects and several mites may also transmit forms of malaria to animals.

Complete answer:
Plasmodium, a genus of parasitic protozoans of the sporozoan subclass Coccidia that are the causal organisms of malaria. Plasmodium, which contaminates red blood cells in mammals (including humans), birds, and reptiles, occurs globally, especially in tropical and temperate zones.

The life cycle of Plasmodium that affects humans follows three stages:
- Infection of a human with sporozoites;
- Asexual reproduction and
- Sexual reproduction.

The first two stages take place entirely into the human body, while the third one starts in the human body and is finished into the mosquito organism. The human infection starts when an infected female anopheles’ mosquito bites a human and injects infected with sporozoites saliva into the blood flow. That is the initial living stage of plasmodium (period of infection).

Hence, The correct answer is option (D).

Additional information:
Each schizont gives origin to thousands of merozoites (exoerythrocytic schizogony) that are then exuded into the bloodstream signifying the end of the exoerythrocytic period of the asexual reproductive stage.

Note: The final stage in the malaria life cycle is the asexual reproduction that is separated into diverse phases: the pre-erythrocytic and the erythrocytic phase. Within 30- 60 minutes only after the parasites enter, sporozoites enter through blood circulation to their initial target, the liver. The sporozoites go through the liver cells and start dividing leading to schizonts formation in 6- 7 days.