Lecture Notes on Protists and Malaria

These flashcards cover essential vocabulary and concepts discussed in the lecture on protists, their role in public health, specifically regarding malaria, pathogen life cycles, and treatment options.

Protists

Single cell eukaryotes that are not fungi, plants, or animals.

Encystment

A response by protists to harsh environments, similar to sporulation.

Motile heterotrophs

Animal-like protists that are capable of movement and obtain nutrients by consuming other organisms.

Nonmotile autotrophs

Plant-like protists that do not move and produce their own food through photosynthesis.

Nonmotile heterotrophs

Fungi-like protists that do not move and obtain nutrients by absorbing organic matter.

Plasmodium

Obligate parasite responsible for malaria, infecting vertebrates and insects.

Giardiasis

An intestinal infection caused by the Giardia lamblia parasite, often referred to as 'beaver fever'.

Anaerobic amoeba

A type of protist, such as Entamoeba histolytica, that can survive without oxygen and causes amoebic dysentery.

Toxoplasmosis

A disease caused by Toxoplasma gondii, which can lead to severe outcomes, especially in pregnant women and immunocompromised individuals.

Incubation period

The time span between infection and the appearance of symptoms, approximately 10-15 days for malaria.

Paroxysm

Cyclical occurrence of sudden coldness and shivering followed by fever and sweating, typically seen in malaria.

Severe malaria

A complication of malaria most often caused by P. falciparum, leading to organ failure or unusual blood metabolism.

Recrudescence

The return of symptoms after a symptom-free period, often due to inadequate treatment.

Hypnozoites

Dormant liver stage parasites that can cause relapse of malaria months or years after the initial infection.

Artemisinin-combination therapy

Current standard malaria treatment that combines artemisinin with another drug to prevent resistance.

RTS,S vaccine

A malaria vaccine that reduces uncomplicated malaria incidence by ~40% and was approved for use in children.

Anopheles mosquito

The primary vector for malaria, with around 30 species of major importance.

Merozoites

Infective forms produced by the Plasmodium life cycle that invade red blood cells.

Gametocyte

A sexual form of the malaria parasite, found in the blood, which develops into gametes in the mosquito.

Plasmodium

A genus of parasitic protists that cause malaria in humans and other animals, transmitted via Anopheles mosquitoes.

• Obligate parasites of vertebrates and insects

• Malaria

Trypanosoma spp.

• Parasitic flagellate

• Usually transmitted through vector, usually blood-feeding invertebrate

Giardia lamblia

• Found in food, water, soil contaminated with feces

• Outer shell protects against chlorine

• Giardiasis or ‘beaver fever

Entamoeba histolytica

• Anaerobic amoeba

• Amoebic dysentery, may invade tissues, liver lesions

Toxoplasma gondii

• Obligate intracellular parasite

• Causes congenital toxoplasmosis in humans Entamoeba histolytica

Recrudescence

Symptoms come back because parasites were never fully cleared from the blood.

Where the parasite is hiding:

• Blood (red blood cells)

Why it happens:

• Incomplete or ineffective treatment

• Drug resistance

• Immune system didn’t fully eliminate parasites

Key idea:
Same infection is still there, just flaring back up.

Relapse

What it is:
Symptoms return because dormant parasites in the liver reactivate.

Where the parasite is hiding:

• Liver (hepatocytes)

Why it happens:

• Some species form dormant stages called hypnozoites

Key species:

• Plasmodium vivax

• Plasmodium ovale

Key idea:
Infection was quiet in the liver, then wakes back up later.

How does P. falciparum avoid the immune system?

It causes infected RBCs to stick to blood vessels, avoiding spleen detection.

What is hemozoin?

A crystalline product formed to detoxify heme released from hemoglobin digestion.

What is a malaria paroxysm?

Cycles of chills → fever → sweating lasting 6–12 hours.

Which species causes most severe malaria? and what are the complications

P. falciparum

Respiratory distress

• Severe anemia

• Cerebral malaria (coma)

• Kidney failure

What is reinfection?

A new infection after previous parasites are cleared

What vaccines exist?

RTS,S (Mosquirix) and R21.