Parasitic infections of the GI and GU tracts Flashcards
What is a parasite?
organism that lives on or in a host and gets its food from or at the expense of its host
How are protozoa classified?
according to their movement
What are the 4 classifications of protozoa?
sacromastigophora; apicomplexa; ciliophora and microspora
What are hte further divisions of sacromastigophora?
sarcodina and mastigophora
How do sarcodina move?
by pseudopodia
What characterises sarcomastigophora?
flagellae; pseudopodia or both
Give an example of a sarcodina?
entamoeba
What is a mastigophora?
move by flagella
Give an example of a mastigophora?
giardia
What defines an apicomplexa?
no organelle of locomotion
Give an example of an apicomplexia?
plasmodium
What defines ciliophora?
move by cilia
Give an example of ciliophora?
balantidium
What defines microspora?
spore-forming
Give an example of a microspora?
entercytozoa
What are the 2 phyla of metazoa?
nematodes and platyhelminithes
What are nematodes?
round worms (tubes)
What are the 2 classes of platyhelminthes?
cestodes and trematodes
What are platyhelminithes?
flat worms-dorsoventrally flattened
What are the differences between cestodes (tapeworms) and trematodes (flukes)?
cestodes are segmented by have no alimentary canal whereas trematodes are non-segmented with 2 suckers and no head but have an alimentary canal
Give an example of a cestode?
taenia
Give an example of a nematode?
roudnworm-ascaris
Give examples of trematodes?
fasciolopsis; schistosoma
What are the RFs for getting GI parasitic infections?
infected water or food; immunosuppression; nutritional deficiency; foreign travel; oro-anal intercourse
What are the 4 anatomic locations of GI parasites?
lumen only; mucosal attachment; epithelial cell invasion; mucosal invasion
Give an exmaple of a parasite which remins in the lumen only?
ascaris ; entamoeba
Give an example of parasites which attach to the mucosa?
giardia lamlia; tapeworm
give an exmple of parasites which invade the epithelia?
microsporidia
Give an example of a parasite whic hinvades the mucosa?
balantium coli
What is the infective dose required for giardia?
very low- 10-25 cysts
How do giardia multiply?
by binary fission
How do giardia trophozoites attach to the intestines?
attach to villi by ventral sucking disk
How does giardia cause diarrhoea?
attachment physically disrupts intestinal absorption
What causes giardiasis?
giardia lamblia
What causes amoebiasis?
entamoeba histolytica
What is the infecitous form of giardia?
cyst form
What are teh 3 forms of amoebiasis disease?
carrier; intestinal or extra-intestinal
What are the features of intestinal amoebiasis?
abdo pain; colitis- flask shaped ulcers and bloody diarrhoea
What are the features of extra-intestinal amoebiasis?
liver; lung and brain abscesses- fever; leukocytosis and rigors
Where is cryptosporidiosis found in the intestines?
brush border of the intestinal epithelium
How do cryptosporidia replicate?
schizogony- asexual
What is the infectious agent in cryptosporidiosis?
thick walled oocyst (sporulated)
What are the symptoms of trichomoniasis?
watery discharge
How does trichomonas replicate?
longitudinal binary fission
What is the most common helminithic infection worldwide?
ascariasis
What is found in the ascaris eggs infested by humans?
larval worm
What happens when the ingested eggs of ascaris are released?
penetrates the duodenal wall; enters the bloodstream, liver, heart and pulmonary cicrulation
What is the feature of ascariasis in the lungs?
hypersensitivty penumonitis resembling an asthmatic attack
what is the tx for ascariasis?
mebendazole
What is the function of preserving faecal specimens in 10% formalin?
preserves parasitic morphology
What is used for giardia detection in stoll samples?
ELISA
What is saline wet mount examination sued for identification of?
trophozoites; cysts of protozoa; ova/larvae of helminths
What is iodine wet mount used for identification of?
protozoal cysts
What type of drug is generally used for parasitic infections?
“azole” drugs
What drug is used for most protozoa?
metronidazole
