1.1.3. Protozoan Diseases

i. Protozoan Diseases: • Malaria: o Pathogen: Plasmodium species o Vector: Female Anopheles mosquito o Cycle: Human-liver → RBCs → mosquito o Types: Vivax, Malariae, Falciparum (most severe)

Protozoan diseases are infectious diseases caused by protozoa, which are single-celled organisms. One of the most significant protozoan diseases is malaria, caused by the Plasmodium species. Malaria is spread by the female Anopheles mosquito, which acts as a vector for the disease. The life cycle of the malaria parasite involves a complex journey: it first invades the liver, then it infects red blood cells (RBCs) before being transmitted back to mosquitoes, continuing the cycle. There are different types of Plasmodium responsible for malaria, with Plasmodium falciparum being the most severe form and most dangerous for humans.

Imagine the life cycle of the malaria parasite like a relay race. The Anopheles mosquito catches and carries the pathogen (the baton) from one participant (the human body) to another. First, it passes the baton to the liver, which is like the first runner preparing the team for the next stage. Then, it moves to the red blood cells, which are like the final runners before passing the baton to another mosquito, ready for the next participant in a new human.

• Vector: Female Anopheles mosquito • Cycle: Human-liver → RBCs → mosquito

The transmission of malaria occurs specifically through the bite of an infected female Anopheles mosquito. When this mosquito bites a human, it injects the malaria parasites into the bloodstream. Once inside the human body, the parasites travel to the liver where they mature and multiply. After a short time, these parasites leave the liver and enter the bloodstream, infecting red blood cells. During this process, if another mosquito bites the infected person, it can acquire the parasites and continue the transmission cycle.

Think of the female Anopheles mosquito as a ‘mail carrier’ for the malaria disease. When it bites a person, it delivers the ‘mail’ (the malaria parasites) into their bloodstream. After spending time in the person’s ‘mailroom’ (the liver), the parasites can then circulate through the body to ‘deliver new messages’ (infect red blood cells), and if another mosquito bites the infected person, they collect the ‘mail’ and can start delivering it to another human.

• Types: Vivax, Malariae, Falciparum (most severe)

Malaria is primarily caused by different species of the Plasmodium parasite. The three main types include Plasmodium vivax, Plasmodium malariae, and Plasmodium falciparum. Plasmodium vivax is common in many areas but is generally less severe than the others. Plasmodium malariae is less common and often causes milder symptoms. However, Plasmodium falciparum is the most dangerous and can lead to severe illness or death if not treated promptly. Each type has different characteristics, which can affect the symptoms and the approach to treatment.

You can think of the different types of malaria-causing parasites as various airline companies, each with its own routes and service quality. Just like some airlines (like Plasmodium falciparum) offer deluxe service (representing severe symptoms) that can lead to serious issues, while others (like Plasmodium vivax) provide a basic service (representing milder symptoms), they all ultimately serve the same overall purpose but with different outcomes for passengers (the patients).

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