L35- Parasites Flashcards
define parasite, medical parasitology
1) Parasite- living organism requiring prolonged intimate contact with another to meet basic nutritional needs (unicellular protozoa, multicellular helminths)
2) Parasitology- study of human parasites + medical consequences
define host, definitive host, intermediate host, transient host, reservoir host
1) Host- harbors parasite
2) Definitive- animal harboring adult / sexually mature stage of parasite
3) Intermediate- animal where parasitic development occurs, adulthood not reached
4) Transient- larves developing in it, no sexual multiplication is performed
5) Reservoir- animal harboring parasite that can be transmitted to humans
define parasitic infection, parasitic disease, parasitic infestation
1) Infection: invasion by endoparasites (protozoa, helminths)
2) Disease: invasion, pathology produced by endoparasites
3) Infestation: external parasitism by ectoparasites (arthropods)
compare a vector to a carrier
Vector: arthropod or living carrier that transports pathogenic organism from an infected to non-infected host
Carrier: host harboring parasite w/o exhibiting clinical signs/Sxs
define zoonsis
disease involving parasite where normal host is animal and humans can also be infected
describe the regions most parasitic infections predominate
- tropical regions
- places with poverty, poor sanitation / personal hygeine
list the 3 mass intervention strategy examples
- improved sanitation
- vector control
- mass screening / drug administration programs at repeated intervals
(T/F) parasites can one or two intermediate hosts
T- insect transmission is usually one and other animals may have two
describe the steps of pathogenesis of parasitic infections
1- toxic products: enzymes, endotoxins, indole catabolites
2- Mechanical Tissue damage: organ blockage, pressure atrophy, migration
3- Immunopathology: hypersensitivity, autoimmunity, metaplastic changes
(1) are unicellular parasites
(2) are multicellular parasites
1- protozoa
2- metazoa
Protozoan are (uni/multi)-cellular and (non-/motile). They acquire nutrition via (3) and their respiration is described as (4).
1- unicellular
2- motile
3- pino/phago-cytosis or thru specialized site/structure
4- facultative anaerobe
describe the possible life cycles of protozoa
- Most, simple asexual cell division / binary fission of active feeding cell / trophozoite
- Many undergo cyst formation (oocyst)
- Few, complex life cycle with asexual and sexual phases
intestinal protozoa are usually transmitted via (1) and have the following infectious forms: (2)
1- fecal-oral
2- cyst, oocyst, trophozoite
urogenital protozoa are usually transmitted via (1) and have the following infectious forms: (2)
1- sex
2- trophozoite (T. vaginalis)
blood & tissue protozoa are usually transmitted via (1) and have the following infectious forms: (2)
1- insect vectors
2- cyst/trophozoite, pyriform body, oocyst, promastigote, trypmastigote
(intestinal protozoa) trophozoites can transition to cyst/oocyst via (1), and trophozoites have the following traits: (2)
1- Encystment
2- metabolically active, motile, replication/multiplication
(intestinal protozoa) cyst/oocyst can transition to trophozoites via (1), and cysts have the following traits: (2)
1- Excystment
2- passed in feces, non-motile, resistant to hostile environment, no multiplication
primary sources of intestinal protozoa infections are (1), where protozoa are in (2) form
1- fecally contaminated water/food
2- trophozoite / motile form + cysts / non-motile form
Entamoeba histolytica is a (protozoa/metozoa) transmitted via (2) and reproduces (a-/sexually). It has (4) for locomotion, infects (5) to cause (6).
1- protozoa 2- fecal-oral 3- asexually 4- pseudopodia 5- colon 6- bloody diarrhea - amoebic dysentery (+ amoebic liver abscess)
Balantidium coli is a (protozoa/metozoa) transmitted via (2) and reproduces (a-/sexually). It is (highly/im-)motile and infects (5).
1- protozoa 2- fecal-oral 3- asexually 4- highly motile (+ large and ciliated) 5- colon (pigs, humans, rodents)
Giardia lamblia is a (protozoa/metozoa) transmitted via (2) and reproduces (a-/sexually). It infects (4) causing (5).
1- protozoa 2- fecal-oral 3- asexually 4- small intestine 5- malabsorption (flagellate, worldwide distribution)
Trichomonas vaginalis is a (protozoa/metozoa) transmitted via (2) and reproduces (a-/sexually). It causes (4) as its main symptom.
1- protozoa 2- sex 3- asexually 4- vaginal/penile discharge (flagellate urogenital parasite)
Cryptosporidium parvum is a (protozoa/metozoa) transmitted via (2) and reproduces (a-/sexually). It is (highly/im-)motile and commonly infect people that are (5).
1- protozoa 2- fecal-oral 3- both asexually/sexually 4- immotile 5- immunocomprimised
Cyclospora cyatenensis is a (protozoa/metozoa) transmitted via (2) and reproduces (a-/sexually). It is (highly/im-)motile and infects (5) causing (6).
1- protozoa 2- fecal-oral 3- both asexually/sexually 4- immotile 5- small intestine mucosa 6- diarrhea (several wks)
Plasmodium spp is a (highly/im-)motile (protozoa/metozoa) transmitted via (3) causing (4). It has the following 4 species: (5).
1- immotile 2- protozoa 3- Anopheles mosquito 4- malaria 5- P. falciparum, P. vivax, P. ovale, P. malariae
Leishmania spp is a (highly/im-)motile (protozoa/metozoa) transmitted via (3) causing (4).
1- highly motile
2- protozoa
3- sand flies
4- visceral / cutaneous / mucocutaneous leishmaniasis
Trypanosoma is a (protozoa/metozoa) transmitted via (2) in Africa causing (3) or via (4) in South America causing (5).
1- protozoa 2- Tsetse fly 3- sleeping sickness 4- Reduviid big 5- Chaga's disease
Toxoplasma gondii is a (protozoa/metozoa) transmitted via (2) causing (3).
1- protozoa
2- fecal-oral (oocysts via cat feces)
3- severe manifestations + neonatal toxoplasmosis
Malaria is caused by (1) parasite family which in humans matures in (2) and then (3) and finally undergoes sexual reproduction in (4)
1- Plasmodium ssp
2- hepatic cycle
3- erythrocytic cycle
4- mosquitos (Anopheles)
Naegleria fowleris is a (1) species found in (2). It invades through (3) to affect (4) causing (5).
1- free-living amoeba 2- freshwater (lakes/streams) 3- nasal mucosa 4- brain 5- acute meningoencephalitis
Acanthamoeba spp is a (1) species found in (2). It usually contaminates (3) or is contracted via (4) to infect (5) causing (6).
1- free-living amoeba 2- freshwater (lakes/streams) 3- contact solution 4- dust, swimming 5- eye 6- keratitis: eye pain, redness, tearing, loss of vision (potentially)
Metazoa parasites are also called (1) and have the following characteristics: (2)
1- helminthes (worms)
2- eukaryotic/multicellular, have most organ systems, has head/tail, has tissue differentiation (endo/meso/exo)-derm, spend most of life in host
list the 3 main classes of helminthes
- Nemathelminthes (roundworm): Class-Nematoda
- Platyhelminthes (flatworms): Class-Trematoda (flukes), Class-Cestoda (tapeworms)
list the methods of metazoa transmission
fecal-oral, direct skin penetration, ingestion, insect vector
list the infectious form for Cestodes, Nematodes, Trematodes
- Cestodes: proglottid, embryonated egg, cysticercus, cystericercoid
- Nematodes: egg, filariform larvae, 3rd stage larvae
- Trematodes: cercaria, mercercaria
these three factors of helminthes are most critical to its clinical symptoms, (1); combined with (2) and (3), worms may result in the following, (4)
1- size, movement, longevity
2- long-term damage
3- immune stimulation
4- mechanical blockage, pressure from growing parasites, nutritional deficiency
Nematode Infections are mostly (1), but the (2) form will cause (3) and the (4) form will cause (5)
1- asymptomatic
2- larvae infect lungs
3- asthma/pneumonia-like Sxs, cough, SOB, wheezing
4- adults infect intestines
5- n/v/d, bloody stool, abd pain –> severe infection => malnutrition/weight loss
list 4 general features of Nematodes
(round worms)
1) cylindrical bodies, complete digestive tract
2) body covered in cuticle, oral opening w/ hooks/suckers to attach to mucosal epithelium
3) male and female sexes (produces eggs w/in human host)
4) presence of worms. larvae, eggs is diagnostic
describe Nematode life-cycle
1) egg –> hatches
2) larva (4 stages): pre-parasitic, free-living or intermediate host until 3rd stage (then see adult)
3) adult: parasitic, definitive host
Ascaris is a (ces/nema/trema)-tode, aka (2) and is transmitted via (3) infecting (4), while also causing (5)
1- nematode (intestinal) 2- roundworm (6-12 in long) 3- fecal-oral 4- small intestine 5- eosinophilia (worldwide in areas w/ poor hygienic conditions)
Enterobius is a (ces/nema/trema)-tode, aka (2) and is transmitted via (3)
1- nematode (intestinal)
2- pinworm (few mm long, oval)
3- fecal-oral
(worldwide, usually found in children)
Trichuris is a (ces/nema/trema)-tode, aka (2) and is transmitted via (3) causing (4) in heavily infected people
1- nematode (intestinal) 2- whipworm 3- soil 4- diarrhea, rectal prolapse, anemia (in warm, humid conditions)
Ancylostoma and Necator are (ces/nema/trema)-todes, aka (2), and mainly cause (3) in (4) regions
1- nematodes (intestinal)
2- hookworms
3- anemia
4- tropical regions
Strongyloide is a (ces/nema/trema)-tode and infects (2); a very severe infection in (3) people
1- nematode (intestinal)
2- small bowels
3- immuno-comprimised
Toxocara is a (ces/nema/trema)-tode and is transmitted via (2); it commonly causes (3) in children
1- nematode (tissue)
2- fecal-oral via cats/dogs
3- visceral larva migrans (VLM)
Trichinella is a (ces/nema/trema)-tode and is transmitted via (2) to infect (3)
1- nematode (tissue)
2- poorly cooked meat
3- striate muscle (Sxs based on location)
describe life cycle of tissue nematods
1) human ingests undercooked meat with encysted larva
2) larva liberated when cyst is digested
3) parasites mature and mate in upper intestine
4) female worms penetrate mucosa - liberate larva
5) larva carried via bloodstream to muscles (penetrate and encyst)
Onchocerca volvulus is a (ces/nema/trema)-tode, is transmitted via (2) and usually causes (3)
1- nematode (micro-filarial)
2- black fly (Simulium spp)
3- visual impairment, blindness, severe itchin of skin (River Blindness)
filarial nematodes usually affect….
lymphatic system
Wuchereria bancrofti is a (ces/nema/trema)-tode and causes (2)
1- nematode (filarial)
2- lymphatic filariasis
Brugia malayi is a (ces/nema/trema)-tode and causes (2)
1- nematode (micro-filarial)
2- lymphatic filariasis
describe life cycle of filarial nematodes
1) fly host ingests via bite of infected person (intermediate host)
2) develops into infectious larva
3) transmission to human via bite
4) lives in lymphatics, skin, subcutaneous tissue, pleural/peritoneal cavities
5) microfilaria in blood / subcutaneous tissue available for fly host via bite
list the general features of trematodes (flukes)
1) dead end digestive system: nutrients in, digested, expelled thru same opening
2) phylum, platyhelminth, flatworms
3) life cycle requires more than one host –> mollusk and vertebrate
Fasciolopsis buski is a (ces/nema/trema)-tode, aka (2) and infects (3) causing (4)
1- trematode
2- intestinal fluke
3- upper intestine
4- inflammation, ulceration, hemorrhage of SI
(up to 8 m long- Southeast Asia, also affects pigs)
Paragonimius westermani is a (ces/nema/trema)-tode, aka (2) and is transmitted via (3)
1- trematode
2- lung fluke
3- ingestion of infected metacercariae in raw/pickled crustaceans
(Far East / Southeast Asia)
Fasciola hepatica is a (ces/nema/trema)-tode, aka (2) and is transmitted via (3) infecting (4) causing (5)
1- trematode 2- liver fluke 3- ingestion of infected metacercariae encyted on watercress 4- intrahepatic bile ducts 5- fasioloasis + severe anemia (also affects sheep)
Clonorchis sinensis is a (ces/nema/trema)-tode, aka (2) and is transmitted via (3)
1- trematode
2- Chinese liver fluke
3- ingestion of infected metacercariae in raw/pickled crustaceans
(China, Japan, Korea, Taiwan)
Schistoma spp are a (ces/nema/trema)-todes, aka (2) and is transmitted via (3). The (4) and (5) species localize to mesenteric veins and (6) localizes to veins around the bladder.
1- trematode
2- blood fluke
3- skin penetration (from free-living aquatic larval forms / cercariae)
4/5- S. japanicum, S. mansoni
6- S. haematobium
(characterized by eggs with spines in stool (4/5) or urine (6))
list general features of Cestodes (tapeworms)
- several ft long
1) flat segments / proglottids develop sequentially from head/scolex- which uses suckers/hooks to attach to intestinal epithelium. No digestive tract, absorbs nutrients
2) hermaphrodites- proglottid produces sperm/egg (proglottids can break off- most mature further from head)
3) humans are usually definitive host, worse if intermediate host
list typical GI symptoms from Cestode infections
- abdominal discomfort
- diarrhea
- weight loss
- B12 deficiency
larva from Cestodes can be in the following sites causing more severe diseases…
liver, eyes, muscles, ect
Taenia saginata is a (ces/nema/trema)-tode, aka (2) and is transmitted via (3) with (4) as presenting symptoms
1- cestode 2- beef tapeworm 3- contaminated / uncooked beef 4- minimal Sxs (worldwide occurrence)
Taenia solium is a (ces/nema/trema)-tode, aka (2) and is transmitted via (3) with (4) as presenting symptoms
1- cestode
2- pork tapeworm
3- contaminated / uncooked pork containing cystercerci
4- cysticercosis: cysticeri encyst in muscles/brain => epilepsy
(worldwide occurrence)
Echinococcus granulosus, aka (1) and Echinococcus multilocularis, aka (2) are (ces/nema/trema)-todes. (4) results from the ingestion of larval stage and develop into adults cause (5).
1- dog tapeworm 2- rodent tapeworm 3- cestodes 4- Hydatid disease 5- space-occupying lesions of several organs (organ rupture => parasitic release)
