Intro to Parasites Flashcards
Define host
an organism which harbours the parasite
Define symbiosis
living together; close, long term interaction between two different species
Define mutualism
an association in which both species benefit from interaction
Define parasitism
an association in which the parasite derives benefit and the host gets nothing in return but always suffers some injury
Define commensalism
an association in which the parasite only is deriving benefit without causing injury to the host
What are the characteristics of a paratenic host?
host where the parasite remains viable without further dvelopment
What are the charactersitics of an intermediate host?
harbours larval or asexual stages of the parasite, some parasites require two intermediate hosts in which to complete their life cycle
What are the characteristics of a definitive host?
either harbours the adult stage of the parasite or where the parasite utilises the sexual method of reproduction, in the majority of human parasitic infections, man is the definitive host
What is a parasite?
an organism which lives in or on another organism (host) and benefits by deriving nutrients at the other’s expense
Do parasites always cause disease?
No
What are the two main classifications of parasites?
protozoa (micro-parasites) and helminths (macro-parasites)
What are the 4 groups of protozoa?
flagellates, amoeboids, sporozoans, trypanosomes
What are the 2 main groups of helminths?
platyhelminths (flatworms), nematodes (round worms)
Schistisoma is an example of which type of helminth?
trematode
What are the 3 types of lifecycle?
direct, simple indirect and complex indirect
What is the difference between direct and indirect life cycles?
direct - only one host
indirect - more than one host
Briefly describe ASCARIASIS
macroparasite - intestinal nematode, acquired by ingestion of eggs
What type of life cycle does ascariasis have?
direct life cycle
What are the two phases of asciaeriasis infection?
lung migration and intestinal phase
What is caused by the lung migration phase of ascariasis infection?
LOEFFLERS SYNDROME - dry cough, dyspnea, wheeze, eosinophilic pneumonitis
What class of drug is used to treat ascariasis?
albendazole
How does albendazole work?
prevents glucose absorption by worm - worm starves
What is the intermediate host of schistosomiasis?
snails
What chronic disease can be caused by schistosomiasis?
bladder cancer and liver cirrhosis
