Clinical Parasitology 3 - Malaria Flashcards
How do people get infected with plasmodium?
Bite of the Anopholes mosquito
Which four protozoa cause malaria?
- Plasmodium falciparum (most common and deadly of the 4)
- Plasmodium vivax
- Plasmodium ovale
- Plasmodium malariae
What is the form of Plasmodium that is transmitted via mosquito bite (stage of life cycle)?
Sporozoites–> thin, motile, spindle shaped forms
Where does Plasmodium infect first after getting into bloodstream? What does it do once there?
Infects the liver (pre-erythrocytic cycle)–> rounds up to form a ball in the liver cell, now called a trophozoite
What do trophozoites do in the liver? What are they then called?
Undergo nuclear division, forming thousands of new nuclei–> now called a Schizont
What happens to Schizonts after they form from trophozoites in hepatocytes? What are they called now?
Cytoplasmic membranes form around each of the thousands of nuclei that make up the schizont, forming thousands of small bodies called Merozoites
After merozoites form in hepatocytes, what happens?
Overloaded hepatocytes burst, releasing merozoites into the liver and bloodstream.
*Some merozoites reinfect liver cells, others now infect red blood cells, beginning the exo-erythrocytic cycle
What are the steps in the erythrocytic cycle of Plasmodium life cycle?
- Merozoite rounds up to form a trophozoite
- Nuclear division to form a schizont
- Cytoplasm surrounds each nucleus forming the schizont, forming more merozoites
- RBC lyses, releasing merozoites
* in RBC, trophozoite looks like a “diamond ring”
* process very similar to the pre-erythrocytic stage
What part of the life cycle stimulates an immune response resulting in fever, chills, and sweats?
Lysis of cells releasing merozoites
How do mosquitoes get sporozoites into their salivary glands?
A few merozoites will change into male or female gametocytes; if these are taken up in a blood meal by a mosquito, they undergo sexual division in the mosquito and then travel to mosquito salivary gland
*Plasmodium undergo asexual division in the human host only; sexual in mosquito
Which two species of Plasmodium can produce dormant forms that remain in the liver?
- P. vivax
- P. ovale
*these forms are called Hypnozoites; can grow years later, causing relapsing malaria
Which species of Plasmodium is a quartan form? Meaning?
P. malariae–> produces cycles of fever, chills, sweating every 72 hours
*By convention, zero hours is one; 24 hours is 2, 48 is 3 (or tertian); so 72 hours is 4
What two species have a tertian form?
P. ovale and vivax–> episodes of fevers, chills, sweating every 48 hrs
How often does P. falciparum cause fever, etc.?
Irregularly, so RBC lysis every 36-48 hrs
*these usually cause continuous fever, chills, sweating!
Which species of Plasmodium can cause severe clinical manifestation, including brain and kidney complications?
P. falciparum
