12. Apicomplexan Parasites

Question 1

4 Structures of the apical complex

Answer 1

1. micronemes
2. rhoptries
3. polar rings
4. sometimes conoids within polar ring

Question 2

Outline of apicomplexan life cycle

Answer 2

gametes - zygote- (sporogeny) - sporozoites - meroziotes (merogeny) - (gametogony) - gametes

Question 3

What is the vector of plasmodium malaria spp?

Answer 3

Female anopheles mosquito

Question 4

at which stage of life cycle does the parasite invade human liver cells?

Answer 4

sporozoite

Question 5

What accounts for the intermittent fever occurring at 48 or 72 hour intervals?

Answer 5

rupture of infected erythrocytes and release of antigens and waste products

Question 6

Which species causes cerebral malaria?

Answer 6

P. falciparum

Question 7

Extrinsic factors affecting malaria (3)

Answer 7

Control and preventative measures
Environmental conditions
Social, behavioural, economic and political factors

Question 8

Intrinsic malaria factors

Answer 8

human
parasite
mosquito

Question 9

Example of anti-larval and adults control

Answer 9

Panama Canal Zone, 1904-1914 - larviciding and large scale environmental modification

Question 10

Example of pyrethrum spraying

Answer 10

1936-1939 South Africa, Netherlands, India

Question 11

Indoor residual spraying with DDT example

Answer 11

Cyprus, Guyana, Venezuela and Greece

Question 12

insecticide-impregnated bed nets

Answer 12

1987-2003

Question 13

Why are pyrethroids good for use in ITNs?

Answer 13

High residual effect: they do not rapidly break down unless washed or exposed to sunlight.
Low mammalian toxicity but highly toxic to insects

Question 14

Name 4 insecticides from cheapest to most expensive

Answer 14

DDT
Malathion
Deltamethrin
Pyrimiphosmethyl

Question 15

Why are vaccines ineffective?

Answer 15

Genes are very variable and are often switched

Once a person is cured, susceptibility returns due to gene switching

Question 16

Which blood group can P. vivax enter the erythrocytes of?

Answer 16

Duffy blood group

Question 17

What occurs in terms of AA sequence in sickle cell anaemia?

Answer 17

glutamic acid in the AA sequence of haemoglobin is replaced by a valine
reduces oxygen carrying capacity

Question 18

One example of a drug that targets parasites in the liver

Answer 18

primaquine

malarone

Question 19

One example of a drug that targets ASEXUAL parasites in RBCs

Answer 19

chloroquine

Question 20

One example of a drug that targets SEXUAL parasites in RBCs

Answer 20

primaquine

Question 21

How does chloroquine work?

Answer 21

Targets the food vacuole of the parasite

Question 22

Factors contributing to treatment failure

Answer 22

Self treatment - may stop taking drug once feels better
Poor compliance - may not complete treatment due to bad side effects
Mass administration - widespread use of a drug increases mutation pressure
Longer half life - drug slowly eliminated, exposes to parasite to sub therapeutic drug concentrations for longer