Parasite Identification

Question 1

where are 90% of malaria cases and deaths

Answer 1

sub-saharan africa

Question 2

what causes malaria

Answer 2

protozoan parasite of the genus plasmodiumn

Question 3

what are the 5 species of plasmodium that infect humans

Answer 3

P.falciparum
P.ovale (has 2 genetic subtypes)
P. vivax
P.malariae
P.knowlesi

Question 4

how is malaria transmitted

Answer 4

via the female anopheles mosquito. the female requires a blood meal for egg development.

Question 5

where is transmission of malaria most common

Answer 5

in areas with stagnant water as this is where eggs are laid

Question 6

need to go over malaria life cycle and human malaria life cycle

Question 7

what is the human life cycle of malaria>

Answer 7

the sporozoites that have been injected into the blood by the mosquito travel to the liver
the sporozoites mature into schizonts, which rupture and release merozoites, in p.ovale and p.viva a dormant liver form (hypnozoite) is formed at this stage
the merozoites travel into the blood, where they infect erythrocytes, forming trophozoites
trophozoites develop into either gametes or schizonts
schizonts allow asexual reproduction and therefore replication, gametocytes allow sexual reproduction inside mosquitoes

Question 8

review blood film morphology

Question 9

parasite identification - thin films - field method

Answer 9

fix film in methanol for 1 min
wash off with water
using pipette cover the film with dilute field’s stain B (1 part stain to 4 parts buffered water)
immediately add equal volume of field’s stain A and mix by tilting the slide
leave to stain for 1 min
wash off and clean with water
place upright in rack to dry

Question 10

parasite identification - thin films - giemsa method

Answer 10

fix methanol 5 mins
for 3% giemsa stain measure 50ml buffered water (ph 7.2) and add 1,5ml giemsa stain and mix gently
for 3% giemsa solution slide satined for 30 mins
10% giemsa stain 45ml buffered water and add 5ml giemsa stain and mix gently
10% slide stained for 10 mins
wash with water, dry back of slide and air dry

Question 11

how do you make a thick film

Answer 11

place 3 drops of blood towards the centre of the slide
the drops should be placed in a roughly triangular shape, with 2 drops at the bottom and one at then top
using the corner of another slide (spreader) join the 3 drops, mixing up to 10x. the film should have a diameter of about 1cm
allow the film to dry completely
an ideal thick film will when wet just allow you to read the newspaper print through it

Question 12

no thick films require fixation?

Answer 12

no

Question 13

parasite identification-thick film-giemsa method

Answer 13

1/20 giemsa solution is used (with buffered water ph7.2)
staining for 30 mins
gently washed in clean water and allow to dry

Question 14

parasite identification-thick film- fields method

Answer 14

polychrome methylene blue (A)
eosin (B)
dip the dry film into solution A for 3 seconds
remove from A and dip gently into clean water (beaker and gently running water)
dip the slide into field’s stain B solution for 3 seconds
dip films in water for 1-2 seconds
place to dry in vertical position