5 Parasites Flashcards
Define: parasite.
An organism which lives in or on another organism and benefits by deriving nutrients at the other’ s expense.
Differentiate between symbiosis, mutualism and commensalism.
S: Close, long term interaction.
M: Both species benefit.
C: Parasite derives benefit without harming host.
What are the three classes of host?
Definitive: harbours adult stage/parasite sexually reproduces
Intermediate: harbours laval/asexual stages of parasite
Paratenic: parasite remains viable without further development
What are the four types of protozoa (micro-parasites)?
Flagellates.
Amoeboid’s.
Sporozoa.
Trypanosomes.
What are the two types of helminths (macro parasites)? What are the two subdivisions of these?
Platyhelminths (flatworms): cestodes (tapeworms), trematodes (flukes).
Nematodes (round worms): intestinal and tissue.
Which parasite causes ascariasis? How is it acquired and where is it found? What type of host is the human?
Ascaris lumbricoides.
Ingestion of eggs (faeces).
S.E. Asia
Definitive.
Ascariasis migrates to two places in the body - where? What does it cause there?
Eggs to Lung: Loefflers syndrome - cough, wheeze, heamoptysis, eosinophilic pneumonitis
Worms to Intestines: malnutrition, obstruction
How is ascariasis diagnosed, treated and controlled?
Observation in stool.
Albendazole (prevents glucose absorption - starves+detaches).
Control: sanitation, edu, deworming
What is schistosomiasis caused by? Where is it found? What is the intermediate host?
aka bilharzia
Schistosoma.
Fresh water lakes in Africa.
Snails.
What does schistosomiasis cause in the body?
Swimmers itch, Katayama fever.
Schistosome haematobium migrates to the urinary system - what does it cause there?
Haematuria. Bladder fibrosis. Squamous cell CA.
Which types of Schistosoma cause portal hypertension and liver cirrhosis?
S. mansoni
S. intercallatum
S. japonicum
S. mekongi
How is schistosomiasis diagnosed, treated and controlled?
Urinary + stool microscopy.
Praziquantel (increases worm ionic permeability + dies).
Kill snails, chemoprophylaxis, avoidance, sanitation.
What is hydatid disease caused by? Where is it found? What is the usual host (we are accidental)?
Echinococcus.
All over the world
Sheep and dogs.
Echoinococcus granulosus.
E multilocularis.
What type of hydatid disease does each cause?
Cystic.
Alveolar.
What does hydatid disease do to the body?
Cysts -70% liver, 20% lungs. May remain asymptomatic. Mass effect. Secondary bacterial infection. Rupture - hypersensitivity.
How is hydatid disease diagnosed and controlled?
Imaging, serology.
Deworming, hand hygiene, safe carcass disposal.
What is malaria caused by? Where is it found? What type of host is the human?
Plasmodium: falciparum, vivax, ovale, malariae.
Equatorial areas.
Definitive.
What are the clinical complications of malaria? (9).
Fever, rigors. Cerebral malaria. Renal failure. Hypoglycaemia. Pulmonary oedema. Circulatory collapse. Anaemia. DIC.
How does malaria cause its clinical effects?
Ruptures red cells, blocks capillaries and causes inflammatory reaction.
How is malaria diagnosed and controlled?
Microscopy, serology, PCR.
Insecticide in homes, larvicide and filling in of breeding pools. Bed nets. Chemoprophylaxis.
What is cryptosporidiosis caused by? Where is it found? Which animals act as a reservoir?
How is it spread?
Cryptosporidium: parvum and hominis.
Worldwide.
Cattle, sheep, goats.
Faecal-oral route.
What does cryptosporidiosis cause?
Watery diarrhoea with mucus.
Bloating, cramps, fever vomiting.
How does cryptosopridiosis affect different people?
Usually self-limiting (2wks).
Severe in young, old, immunocompromised.
