Meaning and Types of Plasmodium

Plasmodium, the parasite that causes human malaria, is among the most researched group of parasites in the world.

Plasmodium is a kind of protozoa, a single-celled organism that is capable of dividing only within a host cell. Plasmodium is usually microscopic and belongs to the domain Eukaryota (organisms that possesses a clearly defined nucleus).

The lifestyle of plasmodium species involves the development of the protozoan in a blood-sucking insect host e. g mosquito, which later injects parasites into a vertebrate host (e.g man) when the insect host feeds on the blood of man. The parasites grow within the vertebrate’s tissue (most times the liver) before entering the bloodstream to infect red blood cells. The disintegration of red blood cells lead to malaria.

Types of Plasmodium

Over the years, many species of plasmodium  were discovered to infect humans. They include the following:

1. Plasmodium falciparum (or P. falciparum)

2. Plasmodium vivax (or P. vivax)

3. Plasmodium malariae (or P. malariae)

4. Plasmodium ovale (or P. ovale)

5. Plasmodium knowlesi (or P. knowlesi)

1. Plasmodium falciparum  (or P. knowlesi)

This is a unicellular (single-celled) protozoan parasite of humans, and the most severe strain of species that causes malaria in humans. About 50% of all malaria cases are caused by Plasmodium falciparum which is transmitted through the bite of a female Anopheles mosquito. In 2018, this parasite led to the death of 405,000 people thus it is regarded as the deadliest parasite in humans. Most malarial deaths are caused by P. falciparum, and 94% of such cases occur in Africa. It is also connected with blood cancer.

2. Plasmodium vivax (or P. vivax)

This parasite is the most frequent and widespread cause of recurring malaria. In terms of virulence, Plasmodium vivax is less fatal than Plasmodium falciparum but can result to severe disease and death. Just like the latter, Plasmodium vivax is also transmitted by female Anopheles mosquito. The parasite is predominant in Asia, Latin America and in some parts of Africa.

3. Plasmodium malariae (or P. malariae)

Another malaria-causing parasite that colonizes the the blood of a human host is the Plasmodium malariae. Due to its low prevalence and milder clinical features, P. malariae is one of the least studied of the species.

4. Plasmodium ovale (or P. ovale)

Plasmodium ovale is a specie of plasmodium which causes tertian malaria (malarial fever recurring every 48 hours) in humans. P. ovale is a rare strain with prevalence rates in most endemic areas. Just like P. vivax, P. ovale causes mild illness and can remain dormant in the liver for many months, causing a relapse some months or years after. Based on research work documented by The Journal of Infectious Diseases, there are about 15 million cases of infection each year with this parasite.

5. Plasmodium knowlesi (or P. knowlesi)

Plasmodium knowlesi is recognized as the fifth species of Plasmodium that causes malaria in humans and other primates. It is prevalent in the Southeast Asia being the main cause of human malaria in Malaysia. P. knowlesi infections cause a variety of disease and are probably fatal, but if detected early enough, infections in humans are readily treatable.

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