Introduction to parasites Flashcards
define parasite
organism which lives on another and benefits by deriving nutrients at the others expense.
define host
organism which harbours the parasite
define symbiosis
Living together close, long term interaction between 2 different species.
define mutalism
association were both species benefit.
define parasitism
an association where the parasite derives benefit and the host gets nothing in return
define commensalism
an association in which the parasite only defining benefit without causing injury to the host.
what are 3 classes of host
definitive- sexual method of reproduction used
intermediate- asexual stages of parasite
paratenic-parasite remains without further development.
2 types of parasites
protazoa-micro
Helminths- macro, worms.
Types of protozoa
- Giardia lamblia- GI
- Cryptosporidum- GI
- Entamboea- GI
- Trypanosoma
Types of helminth
Cestode- taenia sp
Trematode- schistosoma
Intestinal nematode- Ascaris lumbricoides
Tissue nematode- Wuchereria bancrofti- lymphtic system disorder.
3 types of life cycle
- Direct
- Simple indirect
- Complex indirect
what type of parasite is ascariasis
macroparasite- intestinal nematode.
Where is ascariasis spread
poor hygiene areas
what age group does ascariasis affect
3-8 year olds
life cycle of ascariasis
- Worm in intestine lays eggs
- Lost in faeces
- Ingest eggs from contaminated food goes to intestines
- Migrate via portal circulation into lungs.
- Swallowed and passed back into the intestines- hatch and become worms.
2 phases of Ascariasis
Lung migration
Intestinal phase.
what is loefflers syndrome
part of the lung migration phase of ascariasis cycle.
dry cough, dyspnea, wheeze, haemoptysis. eosiniophillic pnemonititis.
how do you diagnose ascariasis
worm or eggs in stool, eggs at top and worms at bottom.
treatment for ascariasis
Albendazole, Benzimidazole
prevent glucose absorption by the worm.
what type of parasite is schistosomiasis
macroparasite- trematode.
what type of cancer can schistosomiasis cause
bladder cancer
What is the intermediate host of schistosomiasis.
snail
Life cycle of schistosomiasis
- In faeces and urine- relase egges as male and femal mate on bowel or bladder.
- Eggs hatch releasing miracidia
- Miracidia penetrate snail tissue
- Sporocysts in snail (successive generations)
- Cercariae released by snail into water and free swimming
- Penetrate human skin
- Cercariae lose tails in penetrtuation and become schistosomulae
- Circulayte in portal blood where they mature.
- Migrate to liver and mature in adults.
clinical problems related to schitosomiasis
swimmers itch- allergic reaction
Katayama fever- spreads into blood causing weight loss
chronic schistomosisasis