L35- Parasites

Question 1

define parasite, medical parasitology

Answer 1

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

Question 2

define host, definitive host, intermediate host, transient host, reservoir host

Answer 2

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

Question 3

define parasitic infection, parasitic disease, parasitic infestation

Answer 3

1) Infection: invasion by endoparasites (protozoa, helminths)
2) Disease: invasion, pathology produced by endoparasites
3) Infestation: external parasitism by ectoparasites (arthropods)

Question 4

compare a vector to a carrier

Answer 4

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

Question 5

define zoonsis

Answer 5

disease involving parasite where normal host is animal and humans can also be infected

Question 6

describe the regions most parasitic infections predominate

Answer 6

• tropical regions

- places with poverty, poor sanitation / personal hygeine

Question 7

list the 3 mass intervention strategy examples

Answer 7

• improved sanitation
• vector control
• mass screening / drug administration programs at repeated intervals

Question 8

(T/F) parasites can one or two intermediate hosts

Answer 8

T- insect transmission is usually one and other animals may have two

Question 9

describe the steps of pathogenesis of parasitic infections

Answer 9

1- toxic products: enzymes, endotoxins, indole catabolites
2- Mechanical Tissue damage: organ blockage, pressure atrophy, migration
3- Immunopathology: hypersensitivity, autoimmunity, metaplastic changes

Question 10

(1) are unicellular parasites

(2) are multicellular parasites

Answer 10

1- protozoa

2- metazoa

Question 11

Protozoan are (uni/multi)-cellular and (non-/motile). They acquire nutrition via (3) and their respiration is described as (4).

Answer 11

1- unicellular
2- motile
3- pino/phago-cytosis or thru specialized site/structure
4- facultative anaerobe

Question 12

describe the possible life cycles of protozoa

Answer 12

• 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

Question 13

intestinal protozoa are usually transmitted via (1) and have the following infectious forms: (2)

Answer 13

1- fecal-oral

2- cyst, oocyst, trophozoite

Question 14

urogenital protozoa are usually transmitted via (1) and have the following infectious forms: (2)

Answer 14

1- sex

2- trophozoite (T. vaginalis)

Question 15

blood & tissue protozoa are usually transmitted via (1) and have the following infectious forms: (2)

Answer 15

1- insect vectors

2- cyst/trophozoite, pyriform body, oocyst, promastigote, trypmastigote

Question 16

(intestinal protozoa) trophozoites can transition to cyst/oocyst via (1), and trophozoites have the following traits: (2)

Answer 16

1- Encystment

2- metabolically active, motile, replication/multiplication

Question 17

(intestinal protozoa) cyst/oocyst can transition to trophozoites via (1), and cysts have the following traits: (2)

Answer 17

1- Excystment

2- passed in feces, non-motile, resistant to hostile environment, no multiplication

Question 18

primary sources of intestinal protozoa infections are (1), where protozoa are in (2) form

Answer 18

1- fecally contaminated water/food

2- trophozoite / motile form + cysts / non-motile form

Question 19

Entamoeba histolytica is a (protozoa/metozoa) transmitted via (2) and reproduces (a-/sexually). It has (4) for locomotion, infects (5) to cause (6).

Answer 19

1- protozoa
2- fecal-oral
3- asexually
4- pseudopodia
5- colon
6- bloody diarrhea - amoebic dysentery (+ amoebic liver abscess)

Question 20

Balantidium coli is a (protozoa/metozoa) transmitted via (2) and reproduces (a-/sexually). It is (highly/im-)motile and infects (5).

Answer 20

1- protozoa
2- fecal-oral
3- asexually
4- highly motile (+ large and ciliated)
5- colon (pigs, humans, rodents)

Question 21

Giardia lamblia is a (protozoa/metozoa) transmitted via (2) and reproduces (a-/sexually). It infects (4) causing (5).

Answer 21

1- protozoa
2- fecal-oral
3- asexually
4- small intestine
5- malabsorption
(flagellate, worldwide distribution)

Question 22

Trichomonas vaginalis is a (protozoa/metozoa) transmitted via (2) and reproduces (a-/sexually). It causes (4) as its main symptom.

Answer 22

1- protozoa
2- sex
3- asexually
4- vaginal/penile discharge
(flagellate urogenital parasite)

Question 23

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).

Answer 23

1- protozoa
2- fecal-oral
3- both asexually/sexually
4- immotile
5- immunocomprimised

Question 24

Cyclospora cyatenensis is a (protozoa/metozoa) transmitted via (2) and reproduces (a-/sexually). It is (highly/im-)motile and infects (5) causing (6).

Answer 24

1- protozoa
2- fecal-oral
3- both asexually/sexually
4- immotile
5- small intestine mucosa
6- diarrhea (several wks)

Question 25

Plasmodium spp is a (highly/im-)motile (protozoa/metozoa) transmitted via (3) causing (4). It has the following 4 species: (5).

Answer 25

``` 1- immotile 2- protozoa 3- Anopheles mosquito 4- malaria 5- P. falciparum, P. vivax, P. ovale, P. malariae ```

Question 26

Leishmania spp is a (highly/im-)motile (protozoa/metozoa) transmitted via (3) causing (4).

Answer 26

1- highly motile 2- protozoa 3- sand flies 4- visceral / cutaneous / mucocutaneous leishmaniasis

Question 27

Trypanosoma is a (protozoa/metozoa) transmitted via (2) in Africa causing (3) or via (4) in South America causing (5).

Answer 27

``` 1- protozoa 2- Tsetse fly 3- sleeping sickness 4- Reduviid big 5- Chaga's disease ```

Question 28

Toxoplasma gondii is a (protozoa/metozoa) transmitted via (2) causing (3).

Answer 28

1- protozoa 2- fecal-oral (oocysts via cat feces) 3- severe manifestations + neonatal toxoplasmosis

Question 29

Malaria is caused by (1) parasite family which in humans matures in (2) and then (3) and finally undergoes sexual reproduction in (4)

Answer 29

1- Plasmodium ssp 2- hepatic cycle 3- erythrocytic cycle 4- mosquitos (Anopheles)

Question 30

Naegleria fowleris is a (1) species found in (2). It invades through (3) to affect (4) causing (5).

Answer 30

``` 1- free-living amoeba 2- freshwater (lakes/streams) 3- nasal mucosa 4- brain 5- acute meningoencephalitis ```

Question 31

Acanthamoeba spp is a (1) species found in (2). It usually contaminates (3) or is contracted via (4) to infect (5) causing (6).

Answer 31

``` 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) ```

Question 32

Metazoa parasites are also called (1) and have the following characteristics: (2)

Answer 32

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

Question 33

list the 3 main classes of helminthes

Answer 33

- Nemathelminthes (roundworm): Class-Nematoda | - Platyhelminthes (flatworms): Class-Trematoda (flukes), Class-Cestoda (tapeworms)

Question 34

list the methods of metazoa transmission

Answer 34

fecal-oral, direct skin penetration, ingestion, insect vector

Question 35

list the infectious form for Cestodes, Nematodes, Trematodes

Answer 35

- Cestodes: proglottid, embryonated egg, cysticercus, cystericercoid - Nematodes: egg, filariform larvae, 3rd stage larvae - Trematodes: cercaria, mercercaria

Question 36

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)

Answer 36

1- size, movement, longevity 2- long-term damage 3- immune stimulation 4- mechanical blockage, pressure from growing parasites, nutritional deficiency

Question 37

Nematode Infections are mostly (1), but the (2) form will cause (3) and the (4) form will cause (5)

Answer 37

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

Question 38

list 4 general features of Nematodes

Answer 38

(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

Question 39

describe Nematode life-cycle

Answer 39

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

Question 40

Ascaris is a (ces/nema/trema)-tode, aka (2) and is transmitted via (3) infecting (4), while also causing (5)

Answer 40

``` 1- nematode (intestinal) 2- roundworm (6-12 in long) 3- fecal-oral 4- small intestine 5- eosinophilia (worldwide in areas w/ poor hygienic conditions) ```

Question 41

Enterobius is a (ces/nema/trema)-tode, aka (2) and is transmitted via (3)

Answer 41

1- nematode (intestinal) 2- pinworm (few mm long, oval) 3- fecal-oral (worldwide, usually found in children)

Question 42

Trichuris is a (ces/nema/trema)-tode, aka (2) and is transmitted via (3) causing (4) in heavily infected people

Answer 42

``` 1- nematode (intestinal) 2- whipworm 3- soil 4- diarrhea, rectal prolapse, anemia (in warm, humid conditions) ```

Question 43

Ancylostoma and Necator are (ces/nema/trema)-todes, aka (2), and mainly cause (3) in (4) regions

Answer 43

1- nematodes (intestinal) 2- hookworms 3- anemia 4- tropical regions

Question 44

Strongyloide is a (ces/nema/trema)-tode and infects (2); a very severe infection in (3) people

Answer 44

1- nematode (intestinal) 2- small bowels 3- immuno-comprimised

Question 45

Toxocara is a (ces/nema/trema)-tode and is transmitted via (2); it commonly causes (3) in children

Answer 45

1- nematode (tissue) 2- fecal-oral via cats/dogs 3- visceral larva migrans (VLM)

Question 46

Trichinella is a (ces/nema/trema)-tode and is transmitted via (2) to infect (3)

Answer 46

1- nematode (tissue) 2- poorly cooked meat 3- striate muscle (Sxs based on location)

Question 47

describe life cycle of tissue nematods

Answer 47

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)

Question 48

Onchocerca volvulus is a (ces/nema/trema)-tode, is transmitted via (2) and usually causes (3)

Answer 48

1- nematode (micro-filarial) 2- black fly (Simulium spp) 3- visual impairment, blindness, severe itchin of skin (River Blindness)

Question 49

filarial nematodes usually affect....

Answer 49

lymphatic system

Question 50

Wuchereria bancrofti is a (ces/nema/trema)-tode and causes (2)

Answer 50

1- nematode (filarial) | 2- lymphatic filariasis

Question 51

Brugia malayi is a (ces/nema/trema)-tode and causes (2)

Answer 51

1- nematode (micro-filarial) | 2- lymphatic filariasis

Question 52

describe life cycle of filarial nematodes

Answer 52

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

Question 53

list the general features of trematodes (flukes)

Answer 53

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

Question 54

Fasciolopsis buski is a (ces/nema/trema)-tode, aka (2) and infects (3) causing (4)

Answer 54

1- trematode 2- intestinal fluke 3- upper intestine 4- inflammation, ulceration, hemorrhage of SI (up to 8 m long- Southeast Asia, also affects pigs)

Question 55

Paragonimius westermani is a (ces/nema/trema)-tode, aka (2) and is transmitted via (3)

Answer 55

1- trematode 2- lung fluke 3- ingestion of infected metacercariae in raw/pickled crustaceans (Far East / Southeast Asia)

Question 56

Fasciola hepatica is a (ces/nema/trema)-tode, aka (2) and is transmitted via (3) infecting (4) causing (5)

Answer 56

``` 1- trematode 2- liver fluke 3- ingestion of infected metacercariae encyted on watercress 4- intrahepatic bile ducts 5- fasioloasis + severe anemia (also affects sheep) ```

Question 57

Clonorchis sinensis is a (ces/nema/trema)-tode, aka (2) and is transmitted via (3)

Answer 57

1- trematode 2- Chinese liver fluke 3- ingestion of infected metacercariae in raw/pickled crustaceans (China, Japan, Korea, Taiwan)

Question 58

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.

Answer 58

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))

Question 59

list general features of Cestodes (tapeworms)

Answer 59

- 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

Question 60

list typical GI symptoms from Cestode infections

Answer 60

- abdominal discomfort - diarrhea - weight loss - B12 deficiency

Question 61

larva from Cestodes can be in the following sites causing more severe diseases...

Answer 61

liver, eyes, muscles, ect

Question 62

Taenia saginata is a (ces/nema/trema)-tode, aka (2) and is transmitted via (3) with (4) as presenting symptoms

Answer 62

``` 1- cestode 2- beef tapeworm 3- contaminated / uncooked beef 4- minimal Sxs (worldwide occurrence) ```

Question 63

Taenia solium is a (ces/nema/trema)-tode, aka (2) and is transmitted via (3) with (4) as presenting symptoms

Answer 63

1- cestode 2- pork tapeworm 3- contaminated / uncooked pork containing cystercerci 4- cysticercosis: cysticeri encyst in muscles/brain => epilepsy (worldwide occurrence)

Question 64

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).

Answer 64

``` 1- dog tapeworm 2- rodent tapeworm 3- cestodes 4- Hydatid disease 5- space-occupying lesions of several organs (organ rupture => parasitic release) ```