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Flashcards in Parasitology Deck (13)
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0
Q

What two groups of organisms are classed as parasites?

A

Protozoa and metazoa

1
Q

Define a parasite and a host

A

Parasite - an organism that grows, feeds and is sheltered on or in a different organism while contributing nothing to it’s survival
Host - an animal or plant that nourishes and supports the parasite, he host does not benefit and is often harmed by the association

2
Q

What is a Protozoa?

A

Single celled eukaryotic organism
Includes - obligate intracellular pathogens
- Extracellular pathogens

3
Q

Name some obligate intracellular pathogens (6)

A
Cryptosporidium 
Toxoplasma 
Plasmodium
Eimeria
Trypanosoma
Leishmania
4
Q

What does T. cruzi cause?
What does leishmania cause?
What does T. gondii cause?

A

Chagas disease
Cutameous leishmaniasis
Congenital toxoplasmosis

5
Q

Name some Extracellular pathogens

A
Acanthamoeba species
Naegleria 
Hartmanella
Giardia species
Entamoeba
6
Q

Describe parasitic life cycles?

A
Many transmitted by insects 
- plasmodium (mosquito)
- leishmania (sandfly)
- trypanosoma (tse tse fly)
Many transmitted by faecal oral route 
- cryptosporidium
- toxoplasma
- giardia
- entamoeba
7
Q

What is plasmodium?

A
Parasite that causes malaria
\+200 different species
At least 10 infect humans
Transmitted by female anopheles mosquito 
Clinical manifestations
- celebral malaria
- splenomegaly
- progressive anaemia
Probably originated in Africa
Mosquito fossils up to 30 million years old show vector for malaria
8
Q

Symptoms of malaria

A
Appear between 19 days and 4 weeks after initial bite
Can take up to a year before symptoms start to show
Benign malaria 
- flu like symptoms
Can last a few weeks but usually last a few days with treatment 
Malignant malaria 
Plasmodium falciparum
Symptoms begin like benign malaria 
Lead to severe complications 
- liver failure
- cerebral malaria
- shock
9
Q

Features of amoeba

A
Protests that have adopted a crawling like method of locomotion
Move by means of pseudopods
First discovered in 1757
Free living organisms that are increasingly important as pathogenic parasitic organisms: 
- entamoeba
- acanthamoeba 
- naegleria 
No definite shape
Food intake is through phagocytosis
Reproduction through mitosis and cytokinesis
Life cycle consists of two stages 
- trophozoite
- cyst
10
Q

What is acanthamoeba keratitis?

A

A progressive sight threatening corneal disease
Leading risk factor is to contact lens wearers
Most common type of acanthamoeba infection
Reactivation often occurs

11
Q

What is granulomatous amoebic encephalitis?

A

CNS infection in the brain tissue of immunocompromised hosts
Acanthamoeba trophozoites spread from the primary site of infection and cross the blood brain barrier
Often misdiagnosed

12
Q

What is cutaneous acanthamoebiasis?

A

Characterised by presence of hard erythematous nodules or skin ulcers
Can occur with or without CNS involvement
Most commonly found in aids patients