Question

Infective stage of Plasmodium that infects human beings is
A. Schizont
B. Sporozoite
C. Trophozoite
D. Cryptozoite

Answer 1

Hint:
Various types of microorganisms are pathogenic in nature and have the tendency to infect as parasites and cause infections and diseases. The plasmodium is an infectious microorganism which is the main causative agent to cause diseases in humans.

Complete Solution:
Plasmodium belongs to a genus of unicellular eukaryotic organisms that are the obligate parasites in humans and other organisms like insects and animals. It is a member of the phylum Apicomplexa which is a large group of parasites infecting the eukaryotic organisms. The different species of the plasmodium are distributed around the globe and are more prevalent in the areas where suitable hosts are found.

The life cycle of Plasmodium species involves its development and growth in a blood-feeding insect as host. The blood feeding insects act as the primary host for the plasmodium species. Further, when the insect bite any other animal or human, the insect happens to inject the parasites into the organism’s body. The parasites then enter the vertebrate organism and carry out further processes of infecting the animal. They grow inside the body of the vertebrate in their tissues most preferably in the liver tissues and after some time they enter the blood steam. In the bloodstream, they cause destruction of the red blood cells and cause a disease known as malaria.

In the life cycle of the Plasmodium, it involves different distinct stages in both the host, the insect and the vertebrate. When a blood sucking insect takes a blood meal by sucking the blood of a vertebrate, it allows passage of the parasite into the bloodstream of the animal. This stage of the parasite in which it infects the vertebrate is known as the sporozoite stage. The sporozoites enter the blood of the animal and migrate to the liver. Inside the liver, the sporozoites grow and multiply and mature into schizonts. Each cell which is known as schizonts then multiplies to produce thousands of merozoites.

After their growth in the liver, the merozoites move to the bloodstream of the vertebrate and here they infect the red blood cells. They cause rupturing of the blood cells. Some of the sporozoites which escape into the bloodstream, then are again picked up by the blood feeding insect.
Therefore, the correct answer or option here will be option B.

Note: The infecting stage of Plasmodium is caused by the transfer of the parasite from a blood sucking insect such as mosquitoes. When during a blood feed, the infected mosquito shares the infection in the form of sporozoites or sporozoite spores of the Plasmodium. The sporozoites after entering the body of the vertebrate such as humans infect the liver and the blood cells and cause malaria.