Parasitic microbial eukaryotes
Apicomplexa – ‘sporozoa’
- Includes the following taxa:
o Plasmodium (responsible for malaria) and Cryptosporidium
o Gregarines – parasites of marine, freshwater and terrestrial animals (Ascidians) –
invertebrates
o Coccidia – Toxoplasma gondi (causative agent of toxoplasmosis)
- Possess apicoplasts – modified plastid from red algae (note contains separate DNA as a residual
chloroplast)
- Also possess micronemes – found at the apical end of the cell, they help to attach to and penetrate
host cells.
Reproduction
- Multiple fission – sexual and asexual
- The apical complex is the first part of the daughter cell to form, originating from the nucleus.
- Several rounds of mitosis without cytokinesis followed by multiple cleavage resulting in
simultaneous production of a set of progeny cells.
Plasmodium falciparum
- Vector is the mosquito of the genus Anopheles.
- Transfer to human hosts occurs by blood.
- Reproduction occurs inside the erythrocytes, resulting in haemolysis.
- Reproduction is asexual in humans and sexual in mosquitoes.
Gregarines
- These are parasitic exclusively of invertebrates.
- Widespread in aquatic and terrestrial environments.
- There is little tissue damage in infection, as development takes place almost entirely outside of host
cells.
- Gregarines are approximately 500µm in length.
Coccidia
- Coccidia are parasites of tissues, whose alternative hosts include dogs, chickens etc.
- Mainly intracellular parasites, they affect the intestinal area.
Toxoplasma gondi
- These are obligate intracellular parasites which are the causative agent of toxoplasmosis.
- Reproducing only in cats and other felines, they infect many other animals and humans in close
proximity as secondary hosts, spread by food, water, unwashed vegetables, contaminated surfaces,
tools, etc.
Apicomplexa – ‘sporozoa’
- Includes the following taxa:
o Plasmodium (responsible for malaria) and Cryptosporidium
o Gregarines – parasites of marine, freshwater and terrestrial animals (Ascidians) –
invertebrates
o Coccidia – Toxoplasma gondi (causative agent of toxoplasmosis)
- Possess apicoplasts – modified plastid from red algae (note contains separate DNA as a residual
chloroplast)
- Also possess micronemes – found at the apical end of the cell, they help to attach to and penetrate
host cells.
Reproduction
- Multiple fission – sexual and asexual
- The apical complex is the first part of the daughter cell to form, originating from the nucleus.
- Several rounds of mitosis without cytokinesis followed by multiple cleavage resulting in
simultaneous production of a set of progeny cells.
Plasmodium falciparum
- Vector is the mosquito of the genus Anopheles.
- Transfer to human hosts occurs by blood.
- Reproduction occurs inside the erythrocytes, resulting in haemolysis.
- Reproduction is asexual in humans and sexual in mosquitoes.
Gregarines
- These are parasitic exclusively of invertebrates.
- Widespread in aquatic and terrestrial environments.
- There is little tissue damage in infection, as development takes place almost entirely outside of host
cells.
- Gregarines are approximately 500µm in length.
Coccidia
- Coccidia are parasites of tissues, whose alternative hosts include dogs, chickens etc.
- Mainly intracellular parasites, they affect the intestinal area.
Toxoplasma gondi
- These are obligate intracellular parasites which are the causative agent of toxoplasmosis.
- Reproducing only in cats and other felines, they infect many other animals and humans in close
proximity as secondary hosts, spread by food, water, unwashed vegetables, contaminated surfaces,
tools, etc.
