Parasitology Flashcards
What two groups of organisms are classed as parasites?
Protozoa and metazoa
Define a parasite and a host
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
What is a Protozoa?
Single celled eukaryotic organism
Includes - obligate intracellular pathogens
- Extracellular pathogens
Name some obligate intracellular pathogens (6)
Cryptosporidium Toxoplasma Plasmodium Eimeria Trypanosoma Leishmania
What does T. cruzi cause?
What does leishmania cause?
What does T. gondii cause?
Chagas disease
Cutameous leishmaniasis
Congenital toxoplasmosis
Name some Extracellular pathogens
Acanthamoeba species Naegleria Hartmanella Giardia species Entamoeba
Describe parasitic life cycles?
Many transmitted by insects - plasmodium (mosquito) - leishmania (sandfly) - trypanosoma (tse tse fly) Many transmitted by faecal oral route - cryptosporidium - toxoplasma - giardia - entamoeba
What is plasmodium?
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
Symptoms of malaria
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
Features of amoeba
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
What is acanthamoeba keratitis?
A progressive sight threatening corneal disease
Leading risk factor is to contact lens wearers
Most common type of acanthamoeba infection
Reactivation often occurs
What is granulomatous amoebic encephalitis?
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
What is cutaneous acanthamoebiasis?
Characterised by presence of hard erythematous nodules or skin ulcers
Can occur with or without CNS involvement
Most commonly found in aids patients
