Plasmodium Life Cycle – Classification, Life Cycle and Diagram

The Plasmodium life cycle involves complex interactions between the parasite, human host, and mosquito vector, leading to the transmission of various diseases including malaria. Plasmodium is a unicellular parasite that falls under the genus protozoans. The Plasmodium life cycle includes development within a blood-feeding insect host, which injects parasites into a vertebrate host during a blood meal.

Plasmodium knowlesi is known to cause malaria, which occurs when a female Anopheles mosquito bites humans or any other mammal. Some other species of Plasmodium are Plasmodium malariae, Plasmodium ovale, and Plasmodium vivax. In this article, we will study the Life Cycle of Plasmodium and its classification.

Plasmodium Classification

The classification of Plasmodium is given below:

Domain	Eukarya
Kingdom	Protista
Sub-kingdom	Protozoa
Phylum	Apicomplexa
Class	Aconoidasida
Order	Haemosporida
Family	Plasmodiidae
Genus	Plasmodium

What is Plasmodium?

Plasmodium belongs to the phylum Apicomplexa and is a eukaryotic organism with a defined nucleus and membrane-bound cell organelles. Plasmodium is an obligate intracellular parasite, meaning it requires a host cell to complete its life cycle. It invades and replicates within the cells of their host organisms, such as human red blood cells or liver cells.

The life cycle of Plasmodium is complex and involves multiple stages. It alternates between sexual reproduction within the mosquito vector (Anopheles mosquitoes) and asexual reproduction within the human or vertebrate host. This complex life cycle enables the transmission and survival of Plasmodium. The transmission of Plasmodium occurs when an infected mosquito bites a human.

Life Cycle of Plasmodium With Diagram

The lifecycle of Plasmodium parasite consist of three stages and it alternates between two hosts: humans and female Anopheles mosquitoes. The cycle has two phases – sexual phase, which occurs in insects and asexual phase that is completed in humans.

The lifecycle of malaria parasite is as follows:

Stage 1 – Gametocyte Formation (Mosquito Phase)

• Anopheles mosquito tranfer microgametocytes (male) and macrogametocytes (female) during blood feeding.
• Inside the mosquito’s gut, these gametocytes transform into sporozoites.
• Male and female gametocytes undergo mating inside mosquito’s gut to form parasite called sporozoite after 15-18 days.

Stage 2 – Sporozoites (Human Phase)

• A female Anopheles mosquito carrying the sporozoite stage of plasmodium bites a human during a blood meal, injecting sporozoites into the bloodstream (the infectious stage of plasmodium),
• Sporozoites travel to the liver and infect hepatocytes (liver cells) and multiply asexually, forming schizonts.
• After sometime, these schizonts rupture to release merozoites.
• This stage is known as the exoerythrocytic or pre-erythrocytic stage.

Stage 3 – Merozoites (Human Phase)

• After a few days or weeks, infected liver cells rupture, releasing merozoites into the bloodstream.
• Merozoites invade red blood cells (erythrocytes) and multiply asexually.
• This cause destruction of infected red blood cells and the release of more merozoites (erythrocytic stage)
• During the erythrocytic cycle, infected individuals experience symptoms such as recurrent fever, chills, and fatigue. These symptoms are characteristic of malaria.

Mosquito Phase

• Inside the mosquito’s midgut, male and female gametocytes fuse, forming a zygote.
• The zygote develops into a motile form called an ookinete, which penetrates the midgut wall and forms an oocyst on the outer surface.
• Within the oocyst, the nucleus of the ookinete undergoes multiple divisions, resulting in the production of thousands of sporozoites.
• When the infected mosquito takes its next blood meal, the sporozoites migrate to its salivary glands. They are then injected into a new human host during subsequent mosquito bites, restarting the cycle.

Conclusion – Life Cycle of Plasmodium

In summary, Plasmodium is a single-celled protozoan parasite belonging to the phylum Apicomplexa. It has a complex life cycle involving both mosquitoes and humans. Mosquitoes transmit the parasite to humans during a blood meal, initiating the infection. Once inside the human body, Plasmodium undergoes various stages of development, causing malaria and its associated symptoms. The Plasmodium life cycle involve alternate stages between sexual and asexual reproduction enables its survival and transmission. By understanding the details of Plasmodium life cycle, we can better combat malaria and work towards its prevention and control.

FAQs on Plasmodium Life Cycle

What is Plasmodium?

Plasmodium is a genus of parasitic protozoa that causes malaria. It is having different species, with the most common ones being Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, Plasmodium ovale, and Plasmodium knowlesi.

What is the Main Host for Plasmodium?

Plasmodium has two main hosts in its life cycle: humans and female Anopheles mosquitoes. Humans serve as the vertebrate host, while mosquitoes act as the insect vector.

How is Plasmodium Transmitted?

Plasmodium is transmitted to humans through the bite of infected female Anopheles mosquitoes. When an infected mosquito feeds on a human, it injects sporozoites into the bloodstream, initiating the infection.

What are the Symptoms of Plasmodium Infection?

Symptoms of Plasmodium infection, known as malaria, include fever, chills, headache, muscle aches, fatigue, and sometimes nausea and vomiting. The severity of symptoms depends on the Plasmodium species and the individual’s immune response.

What is the Asexual Stage of Plasmodium?

Sporozoites is the asexual stage of the Plasmodium. This stage is responsible for causing infection as sporozoites get transmitted from the female Anopheles to humans when they bite.

What are the 3 Stages of Malaria?

The three stages of malaria include the liver stage (pre-erythrocytic), the blood stage (erythrocytic), and the transmission stage (sporogonic). Each stage involves specific interactions between the Plasmodium parasite and its human and mosquito hosts.