Trypanosomes - Disease Protists Flashcards
What do contemporary protists form?
Paraphyletic group
Why do contemporary protists form paraphyletic group?
Doesn’t form a neat branch of closely related organisms
What do Apicocomplexa cause?
Malaria, crypto, toxoplasmosis
What do Entomoeba infection cause?
Amoebiasis
What are excavates?
Ancient group diverged just after emergence of eukaryotes
What are examples of excavates?
Parabasilids
Diplomonads
What are kinetoplastids?
Mitochondria contains kinetoplast
Single flagellum attached to membrane
What are kinetoplast?
A network of circular DNA inside a large mitochondrion that contains many copies of mitochondrial genomes
Where do Trypanosomes live in?
Vertebrate blood
What is the structure of Trypanosomes?
Mitochondria contains kinetoplast
Single flagellum attached to membrane
What is Trypanosomes?
Vector-borne parasites
What are the hosts of Trypanosomes?
All vertebrates clases
What are the vectors of Trypanosomes?
Arthropod and leech vectors
What are different types of pathogenic kinoplastids?
Leishmania
Trypanosoma bruci
Trypanosoma cruzi
What disease does Trypanosoma cruzi cause?
Chagas Disease
How many people are infected with Chagas disease?
8 million people
How many people are infected with Chagas disease in USA?
300,000
What are the vector for Trypanosoma cruzi?
Triatomine bugs
What is the distribution of Chagas Disease?
- Different species of vector locally important cross distribution
- Basic form has common form of lifecycle
- Different stains are associated with particular forms of pathogenicity
What are different forms of pathogenicity of different strains of Trypanosoma cruzi?
Actue form
Chronic form
What subspecies of Trypanosomes infect humans in South and Central America?
Trypanosoma cruzi cruzi
What are the subspecies of Trypanosomes that are morphologically identical to another form infecting bats and other bats?
Trypanosoma cruzi marinkellei
Trypanosome dionisii
What are key life stages of Trypanosoma cruzi?
Trypomastigot
Amastigote
Epimastigote
What is trypomastigote found?
Found in bloodstream of infected vertebrates
What is amastigote found?
Intracellular dividing form in the cytoplasm of vertebrate cells
Where is epimastigote found?
Found in insect vector
What is life cycle of Trypanosoma cruzi?
- Triatomia bug takes blood meal
- Pass metacyclic trypomastigotes in faeces
- Trypomastigote enters bite wound or mucosal membrane
- Metacyclic trypomastigote penetrate various cells at bit wound site
- Inside cell transform to amastigotes
- Amastigote multiply by binary fission
- Intracellular amastigote transform into trypomastigote then burst out of cell into bloodstream
- Trypomastigote can infect other cells and repeat by cycle
- Triatomine bug takes a blood meal
- Epimastigote in midgut
- Multiply in midgut
- Metacyclic trypomastigotes in hindgut
How does Trypanosome cruzi invade host?
Via feeding wound or mucosa
What do Trypanosome cruzi infect?
Muscle, nerves and macrophages
Where does the host localise in Trypanosome cruzi?
Cardiac muscle
Smooth muscle
Autonomic nerves
Macrophages
What is the immune evasion of Trypanosome cruzi?
- Intracellular multiplication (T cells)
- Can grow within macrophages
How can Trypanosome cruzi grow within macrophages?
- Enter cell via the phagocytic vacuole
- Quickly escape the vacuole and move into the cytoplasm
- Safe from destructive enzymic activity
What is the pathology I of chagas disease?
Acute phase
What is the acute phase of chagas disease?
- Trypanosomes first infect mucous membranes then enter bloodstream
- Symptoms: fever, fatigue, body aches, headache and rash
- Serious in children and immunocompromised adults
How long does acute phase last?
8-12 weeks
What is the pathology II of chagas disease?
Chronic phase
What is the chronic phase of chagas disease?
-Very low levels in blood
-No symptoms for 10 years
-Survive in cytoplasm of macrophages and muscle cells epithelial cells and neurones
Intestinal lesions
What is intestinal lesions?
Mega-syndrome of severe intestinal dilation
What causes African sleeping sickness?
Trypanosoma brucei
How many people were reported with African sleeping sickness in 2015?
2804 cases
What are the vector of Trypanosoma brucei?
Tsetse flies
What is the distribution of sleeping sickness?
- Eastern Africa = Trypanosoma brucei rhodesiense
- Western Africa = Trypanosoma brucei gambiense
What are the two different forms of sleeping sickness?
- Trypanosoma brucei rhodesiense
- Trypanosoma brucei gambiense
What are different between the two forms of sleeping sickness?
- Ecology
- Epidemiology
What does the Trypanosoma brucei rhodesiense invade?
Widespread organ damage, acute
What does the Trypanosoma brucei gambiense invade?
Central nervous system, chronic
What is the life-cycle of sleeping sickness?
- Tsetse fly takes blood meal
- Inject metacyclic trypomastigotes
- Injected metacyclic trypomastigotes transforms into bloodstream
- Trypomastigotes multiple by binary fission in various body fluids
- Trypomastigotes in blood
- Tsetse fly takes blood meal
- Bloodstream trypomastigotes ingested
- Bloodstream trypomastigote transform into procyclic trypomastigote in tsetse fly’s midgut and multiply by binary fission
- Procyclic trypomastigote leave midgut and transform into epimastigotes
- Epimastigotes multiply in salivary gland
- Transform into metacyclic trypomastigote
Do Trypanosoma brucei have a natural reservoir?
Yes
Where does the host localise in Trypanosome brucei?
Blood, lymph, cerebrospinal fluid, brain
What is the Trypanosome brucei parasite covered in?
Coat made up of variable surface glycoproteins
How many identical glycoprotein molecules cover parasite surface?
> 10 million
What are variable surface glycoproteins?
Tightly packed, prevents immune recognition/antibodies and protects against lytic compounds in host serum
What do variable surface glycoproteins do throughout course of infections?
Change
What does the variable surface glycoproteins changing throughout course of infection allow?
Avoiding host immune system
What do tsetse fly gut trypanosomes express on surface?
A single antigen called procyclin
How many variable surface glycoprotein does mammalian host express?
+100 different ones
How many variable surface glycoprotein are expressed at the same time?
Only one
How many expression sites do Trypanosomes brucei have?
About 20
What are the two main methods that lead to antigenic variation?
- Use of different variable surface glycoprotein expression site
- DNA recombination changes variable surface glycoprotein present in active expression site
What are the different pathology of sleeping sickness?
Stage 1: Skin lesion may form at bite site. Parasite enters the blood
Stage 2: Parasite enters the nervous system
Death
True or false:
T. brucei contains kinetoplast
True
True or false:
T. cruzi contains kinetoplast
True
True or false:
T. brucei invade the CNS
True
True or false:
T. cruzi invade the CNS
False
True or false:
T. brucei infective forms in insect faeces
False, saliva
True or false:
T. cruzi infective forms in insect faeces
True
