ZOL3703 SUMMARIES
Modern Parasitology
Chapter 1- 3
Chapter 7 - 10
, PARASITIC PROTOZOA
Over 45 000 named species
10 000 are parasitic in invertebrates and in almost every species of vertebrae
Lie between prokaryotic and higher eukaryotic organism (share characteristics of each)
Small, have short generation times, high rates of reproduction and a tendency to induce
immunity to reinfection in hosts that survive
Eukaryotic ells with organelles and metabolic pathways akin to those of the host
STRUCTURE AND FUNCTION
Unicellular eukaryotic cells (1-150µm), parasitic forms tend to the lower size range
Each protozoan is the equivalent of a single metazoan cell with plasma membrane, nucleus, nuclear
membrane, chromosomes, endoplasmic reticulum, mitochondria, Golgi apparatus and ribosomes
Parasitic forms are not simple or degenerate, possess adaptations that include complex life cycles,
specialised ways of entering their hosts and maintaining themselves inside their hosts and their
nutrition, physiology and biochemistry are specialised
Sexual reproduction is important in the sporozoans in which is provides limitless variation and
adaptability
CLASSIFICATION
Classification is based on variation in life cycles, details of fine structure and biochemical and
molecular differences
Protozoa have been divided into 4 major groups based on their mode of locomotion:
1. Flagellates
2. Amoeba (pseudopodia)
3. Ciliates
4. Sporozoans (sessile)
KINETOTOPLASTID FLAGELLATES
Characterised by the possession of a unique organelle called the kinetoplast, contains DNA and is an
integral part of the mitochondrial system
Kinetoplast is situated near the base of the flagella, easily seen in stained preparations
Found in invertebrates and vertebrates (mammals: Leishmania, Trypanosoma,
Endotrypanum)
,Typical form is an elongated organism (promastigote) with a kinetoplast and a flagellum at the
anterior end. Variations occur by the migration of the kinetoplast-flagellum complex within the body
of the flagellate associated with changes in the mitochondrial system
TRYPANOSOMES OF HUMANS IN SOUTH AMERICA (e.g. Trypanosoma cruzi)
Infects 11-12 million people in South and Central America
Infective to about 100-150 species of wild and domesticated mammals
In the armadillo the infection is long lived, unsure if humans act as reservoirs
Vectors are bugs belonging to family Reduvidae
Bugs take up infected blood, the trypanosomes multiple in the epimastigote form in the hind
gut and infective/ metacyclic forms are passed out with faeces
Infect human hosts if they are rubbed into the bite, another wound or the conjunctiva of the
eye
Within human hosts trypanosomes enter various cells (particularly macrophages, muscles and nerve
cells), they round up and multiple in the amastigote form. Amastigotes develop into trypomastigotes
that either enter new cells/ taken up when a vector feeds.
Disease is called Chagas disease, various forms depending on where the amastigotes develop
Cardiac failure due to parasites in heart muscles
Loss of nervous control of the alimentary canal due to parasites in the nervous system
, TRYPANOSOMES OF HUMANS IN AFRICA
Vectors are tsetse flies belonging to family Glossinidae. Trypanosomes usually develop in the midgut
of vectors and are injected from the salivary glands when the fly feeds
Two subspecies infect humans
1. T. brucei gambiense transmitted by wet flies of G. palpalis (riverine conditions in West and
Central Africa, causes chronic sleeping sickness)
2. T.b. rhodesiense transmitted by dry flies of G. morsitans (savanna of East Africa, causes acute
sleeping sickness)
Can infect a range of mammalian hosts, some are important reservoirs of T.b. rhodesiense
Main cause of sleeping sickness is the invasion of trypanosomes in the nervous system
Modern Parasitology
Chapter 1- 3
Chapter 7 - 10
, PARASITIC PROTOZOA
Over 45 000 named species
10 000 are parasitic in invertebrates and in almost every species of vertebrae
Lie between prokaryotic and higher eukaryotic organism (share characteristics of each)
Small, have short generation times, high rates of reproduction and a tendency to induce
immunity to reinfection in hosts that survive
Eukaryotic ells with organelles and metabolic pathways akin to those of the host
STRUCTURE AND FUNCTION
Unicellular eukaryotic cells (1-150µm), parasitic forms tend to the lower size range
Each protozoan is the equivalent of a single metazoan cell with plasma membrane, nucleus, nuclear
membrane, chromosomes, endoplasmic reticulum, mitochondria, Golgi apparatus and ribosomes
Parasitic forms are not simple or degenerate, possess adaptations that include complex life cycles,
specialised ways of entering their hosts and maintaining themselves inside their hosts and their
nutrition, physiology and biochemistry are specialised
Sexual reproduction is important in the sporozoans in which is provides limitless variation and
adaptability
CLASSIFICATION
Classification is based on variation in life cycles, details of fine structure and biochemical and
molecular differences
Protozoa have been divided into 4 major groups based on their mode of locomotion:
1. Flagellates
2. Amoeba (pseudopodia)
3. Ciliates
4. Sporozoans (sessile)
KINETOTOPLASTID FLAGELLATES
Characterised by the possession of a unique organelle called the kinetoplast, contains DNA and is an
integral part of the mitochondrial system
Kinetoplast is situated near the base of the flagella, easily seen in stained preparations
Found in invertebrates and vertebrates (mammals: Leishmania, Trypanosoma,
Endotrypanum)
,Typical form is an elongated organism (promastigote) with a kinetoplast and a flagellum at the
anterior end. Variations occur by the migration of the kinetoplast-flagellum complex within the body
of the flagellate associated with changes in the mitochondrial system
TRYPANOSOMES OF HUMANS IN SOUTH AMERICA (e.g. Trypanosoma cruzi)
Infects 11-12 million people in South and Central America
Infective to about 100-150 species of wild and domesticated mammals
In the armadillo the infection is long lived, unsure if humans act as reservoirs
Vectors are bugs belonging to family Reduvidae
Bugs take up infected blood, the trypanosomes multiple in the epimastigote form in the hind
gut and infective/ metacyclic forms are passed out with faeces
Infect human hosts if they are rubbed into the bite, another wound or the conjunctiva of the
eye
Within human hosts trypanosomes enter various cells (particularly macrophages, muscles and nerve
cells), they round up and multiple in the amastigote form. Amastigotes develop into trypomastigotes
that either enter new cells/ taken up when a vector feeds.
Disease is called Chagas disease, various forms depending on where the amastigotes develop
Cardiac failure due to parasites in heart muscles
Loss of nervous control of the alimentary canal due to parasites in the nervous system
, TRYPANOSOMES OF HUMANS IN AFRICA
Vectors are tsetse flies belonging to family Glossinidae. Trypanosomes usually develop in the midgut
of vectors and are injected from the salivary glands when the fly feeds
Two subspecies infect humans
1. T. brucei gambiense transmitted by wet flies of G. palpalis (riverine conditions in West and
Central Africa, causes chronic sleeping sickness)
2. T.b. rhodesiense transmitted by dry flies of G. morsitans (savanna of East Africa, causes acute
sleeping sickness)
Can infect a range of mammalian hosts, some are important reservoirs of T.b. rhodesiense
Main cause of sleeping sickness is the invasion of trypanosomes in the nervous system
