Week 2 Flashcards
Name the species of malarial parasites that infect humans?
- Five main species that infect humans:
- Plasmodium falciparum
- Plasmodium vivax
- Plasmodium ovale
- Plasmodium malariae
- Plasmodium knowlesi
What are the 3 phases of the malarial parasite life cycle called?
- Sexual
- Liver phase
- Blood phase (asexual)
Where does the sexual phase take place?
Inside the anopheles mosquito - stomach
Describe the blood phase
Merozoites adhere to RBC and enter the cell, start to grow and become a trophozoite. The cell contents are used as food. Trophozoites mature into schizonts which undergo asexual replication, produce
merozoites which rupture from the RBC and continue the cycle. Some merozoites mature into gametocytes instead of shizonts, and when released they can then be taken up by a mosquito.
Which species of malaria can infect liver cells and become dormant?
P. vivax and P. ovale
What is this dormant stage called?
hynozoites
Stages to remember in blood phase
Merozoite Trophozoite Mature Trophozoite Shizont Gametocyte
What are the two types of blood films for malaria examination?
Thick and thin film
What pH of the stain is generally recommended? important?
pH of 7.2 is generally recommended
Name the life cycle stages in the blood cycle of malaria?
Merozoite Trophozoite Mature Trophozoite Shizont Gametocyte
What is thin film used for in malarial blood films?
view parasite morphology
confirm species of malaria
What is thick film used for in malarial blood films?
concentration of malarial parasites.
used to identify quickly if parasites are present
what type of stain is used for malarial blood films?
Giemsa is often used, other Romanowsky stains also
Why can thick film not be fixed before staining?
thick film cannot be fixed before staining, as fixation would prevent osmotic lysis and dehaemoglobinization
What is the technique for examining thick blood films for malaria?
Must focus up and down continually
Routine examination = 100 fields
100 fields = approximately 10 minutes
To obtain the same sensitivity with thin film would take 30 minutes
Which malarial species contains Schuffner’s dots?
P vivax infected cells
Which malarial species contains Maurer’s clefts?
P falciparum infected cells
Two chromatin dots are commonly seen with which species?
P falciparum
Out of P.vivax and P. falciparum which malarial species contains Schuffner’s dots and which contains Maurer’s clefts?
P vivax - Schuffner’s dots
P falciparum - Maurer’s clefts
Which malarial species contains no dots or clefts?
P. malariae
Name this malarial species -
• Commonest species in cooler parts of the tropics
• Largest of the malarial parasites
• Cause of much illness and absenteeism
P vivax
Name this malarial species - Commonest species in tropical areas
• Responsible for most cases of severe malaria and death
P falciparum
Which malarial species has banana shaped gametocytes?
P falciparum
In Plasmodium falciparum are the RBC’s enlarged?
no red cells are not enlarged
In Plasmodium falciparum are there marginal forms?
yes
In Plasmodium vivax are the RBC’s enlarged?
yes
In Plasmodium vivax what shape are the gametocytes?
round
Name this species: slightly enlarged RBC’s sometimes distorted with fimbriated ends or oval in shape. Can contain Schuffner dots
P.ovale
What are the 2 most commonly seen species of malaria in Australia?
P. falciparum and P. vivax
Largest of the malarial parasites
P vivax
Name this species of malaria: Non enlarged, sometimes distorted with crenation, pinkish, bluish and darkened rim, stippling as coarse Maurer clefts
P. falciparum
Name this species of malaria: not enlarged, not distorted and no change in colour, no stippling
P.malariae
Besides microscopy how can malaria be diagnosed?
Rapid diagnostic test
Serological tests
Molecular biological tests
Describe basically how the RDT works
In 15mins this test can detect malaria antigens in a person’s blood. Blood from the patient is placed on a test card with certain reagents after 15mins the specific bands on the test card indicate malarial infection.
Describe basically how serological tests work
Malaria antibody detection using indirect fluorescent antibody test which can identify if a patient has been infected with plasmodium
Name two or three microscopic characteristics that differentiate the most common species in the blood life cycle
P.falciparum has marginal forms and 2 chromatin dots, non enlarged red cells, banana shaped gametocytes
P.vivax enlarged red cells, round gametocytes
List some clinical findings in general malaria
- Fever
- Chills
- Headache
- Malaise
- Vomiting
- Diarrhoea
List some clinical findings in severe malaria
- Renal failure
- Hypoglycaemia
- Severe anaemia
- Pulmonary edema
- Shock
- Convulsion
- Coma
- Haemoglobinuria
