Parasites Flashcards by Amanda Box

List the 5 intestinal nematodes (roundworms)

Pinworm (Enterobius vermicularis)
Ascariasis
Whipworm (Trichuris trichura)
Hookworm (Necator americanus, Anclyostoma duodenale)
Strongyloides

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List the 3 tissue nematodes (roundworms)

Trichinella spiralis (trichinosis)
Wuchereria bancrofti (filariasis)
Toxocara canis, Toxocara cati (visceral/cutaneous larva migrans)

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List the trematode (flukes) vs. cestodes (tapeworm) flatworms

Trematode = Schistosoma (blood fluke)

Cestode = Taenia saginata (intestinal), Taenia solium (intestinal or tissue), Echinococcus granulosus (hyatid cyst disease)

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Treatment = mebendazole/albendazole

Whipworm

Hookworm

Ascariasis

Strongyloides

Trichinella (adult only)

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Tx with metronidazole

Trichomonas

Entamoeba histolyticum

Giardia

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Dx via eggs in feces

Hookworm

Ascarisis

Tapeworm (or proglottid)

Schistosoma japonicum/mansoni

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Dx via larva in feces

Strongyloides

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Dx via ID in urine

Schistosoma haematobium

Legionella

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Dx via cyst in stool

Entamoeba histolyticum

Giardia (or trophozoite)

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Dx via card agglutination test

T. brucei

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Dx via Giemsa stain (thin/thick)

Malaria

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Chronic infection

Strongyloides

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Must be fertilized in soil

Whipworm

Ascariasis

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Larval stage is migratory

Hookworm

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Larva penetrates skin –> migrates in subQ tissue –> inflammation

Toxocara canis/cati

(Cutaneous larva migrans)

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Dx?

Leishmaniasis

(Amastigote form in macrophages)

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Eggs in feces –> rhabdiform larva hatches –> filariform larva penetrates skin –> adults in SI

Hookworm (Necatur americanus, Ancylostoma duodenale)

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Fever + diarrhea + muscle pain + periorbital edema + eosinophilia

Trichinosis

(Trichinella spiralis)

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Snail is essential intermediate host

Schistosoma

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Taken up by and multiplies in macrophages

Leishmaniasis

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Cyst form can survive outside the body

Entamoeba histolyticum

Giardia

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What are the protozoan endoparasites?

Single celled eukaryotes

(Flagellates [Leishmania, Giardia, trypanosomes] + amoebas [Entamoeba, Naegleria] + sporozoea [Cryptosporidium, malaria] + ciliates)

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Daycare

Pinworm (Enterobius vermicularis)

Giardia

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Damage due to eosinophil basic protein

Loeffler’s syndrome

(think Stryongyloides in heart and lung)

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Perianal itching at night

Pinworm (Enterobius vermicularis)

Blood meal --\> releases trophozoite into human --\> infects liver cell --\> schiont --\> ruptured schizont --\> infects RBC --\> immature trophozoite/ring form --\> forms mature trophozoite, ruptures, and reinfects more RBCs OR forms gametocytes --\> gametocytes taken up with blood meal --\> inside vector, microgamete enters macrogamete --\> ookinete --\> oocyst --\> oocyst ruptures --\> trophozoites released --\> blood meal --\> releases trophozoite into human ....

Malaria

Wormballs

Ascariasis (Intestinal obstruction)

Ingested oocyst --\> sporozoites released --\> infect gastric epithelial cells --\> differentiate into merozoites --\> some become male and female gametes --\> fuse to form a zygote --\> reduction division inside zygote --\> oocyst containing 4 sporozoites

Vector for African trypanosomiasis

Tsetse fly

How do you diagnose early lymphatic filariasis/Wuchereria bancrofti?

Microfilaria in blood

Obstructive jaundice +/- seizures and increased ICP

Echinococcus granulosus (Hydatid cyst; presentation depends upon location of the cyst)

Host in which sexual reproduction takes place

Definitive host

Anchovy paste aspirate

Entamoeba histolytics

Transmitted via cysts in meat or oocysts in cat poop

Toxoplasmosis (Toxoplasma gondii)

Egg from cat/dog feces swallowed --\> larva penetrate mucosa --\> enter circulation --\> larva migrate to liver, lungs, eye --\> inflammatory necrosis

Toxocara canis/cati (Visceral larva migrans)

Miracidia

Infective form of Schistosoma in freshwater snails

What are the 3 soil-transmitted helminths?

1. Hookworm (Necator americanus, Ancylostoma duodenale) 2. Whipworm (Trichuriasis) 3. Ascaris lumbricoides

Worldwide distribution

Giardia Toxoplasmosis (Toxoplasma gondii)

Tapeworms

Taenia solium, Taenia saginata

What 3 types of sx can one get with a Whipworm infection?

1. Asymptomatic 2. Diarrhea +/- blood 3. Chronic blood loss/IBD-like sx

How does T. brucei move?

Undulating membrane

Quartan fevers

P. malariae (every 72 hours)

MC helminth infection in US

Pinworm (Enterobius vermicularis)

Intermittent fevers

Malaria African trypanosomiasis (T. brucei)

Penetrates cribiform plate/olfactory neuroepithelium

N. fowleri (Primary amebic meningoencephalitis)

Outcomes of congential toxoplasmosis

70% - normal 5-10% - miscarriage 10% - brain damage 10% - visual problems (chorioretinitis)

Fever, chills, rigors; respiratory distress, pulmonary edema; decreased consciousness, seizures; anemia; HA, N/V, diarrhea; hypoglycemia; lactic acidosis

Malaria

What cannot occur in an intermediate host?

Sexual reproduction (Only growth &/or sexual reproduction occurs)

Fork-like tail

Cercariae form of Schistosoma, allows it to be free-living in freshwater and penetrate skin

Possible parasitic cause?

Chronic T. cruzi infection (Chagas disease; damage to autonomic ganglia causes achalasia)

Liver cyst

Echinococcus granulosus (Hydatid cyst)

Dx?

Trichomonas

How is Ascariasis prevented?

Proper disposal of sewage (Eggs become fertilized in soil)

Purpuric papule + Loeffler's syndrome + N/V + diarrhea + epigastric pain

Strongyloides

Vector of American trypanosomiasis

Reduviid/triatomine bug (Chagas disease)

Blood meal --\> vector picks up metacyclic trypomastigotes --\> transform into procyclic trypomastigotes and multiply in vector's midgut --\> leave the midgut and transform into epimastigotes --\> transform into metacyclic trypomastigotes and multiply in salivary gland --\> blood meal --\> metacylic trypomastigotes transform into bloodstream trypomastigotes in human --\> trypomastigotes multiply in blood/CSF/lymph fluid --\> blood meal ....

T. brucei (African trypanosomiasis)

3 teeth on either side

Hookworm (Necatur americanus, Ancylostoma duodenale)

Dermatitis

Schistosoma (Due to penetration of cercariae)

Acid fast oocysts

Cryptosporidium

Prefers pH \> 4.5

Trichomonas

Hemaphrodites

Tapeworm (T. solium, T. saginata; THINK: only one tapeworm in a host at a time.... has to reproduce somehow)

Diving into fresh water

N. fowleri (Primary amebic meningoencephalitis)

Elevated immunoglobulins

Leishmaniasis (But they're ineffective againt the bug because it's inside macrophages + other cells)

Dx via microfilaria (with multiple nuclei) in blood at night

Wuchereria bancrofti (lymphatic filariasis/elephantiasis)

Sticky tape test

Pinworm (Enterobius vermicularis)

Vector takes blood meal --\> ingests infected cell --\> amastigotes transform into promastigotes in vector's midgut --\> divide --\> migrate to proboscis --\> blood meal --\> promastigotes taken up by macrophages --\> transform into amastigotes in macrophages --\> multiply and macrophages and cells of various tissues --\> blood meal ....

Leishmaniasis

Major cause of iron deficiency anemia in developing countries

Hookworm

Reinfection occurs but with reduced viremia

Malaria

Autoinfection

Strongyloides (Eggs in GI mucosa hatch --\> rhabidiform larva can travel to lung --\> filariform larva travel to trachea --\> swallowed --\> goes to intestine --\> lays eggs --\> repeat)

Hypnozite

Chronic liver state of malaria with P. vivax/ovale

Dx via trophozoites or flagellated form in CSF

N. fowleri (Primary amebic meningoencephalitis)

Camping

Giardia (drink from stream) (or trichinosis if eat raw meat)

Hepatosplenomegaly + ascites

Schistosoma japonicum/mansoni

Latches onto intestinal wall and eats tissue

Hookworm (Necatus americanus, Ancylostoma duodenale)

What respiratory disease can be caused by larval migration through the lungs?

Pneumonitis via Ascariasis

Host in which parasite cannot complete life cycle

Intermediate host (dead-end host)

Produces anticoagulant

Hookworm (Necatur americanus, Ancylostoma duodenale)

Scolex (head) + proglottid (branched uteri)

Tapeworm (T. solium,saginata) Echinococcus granulosus (1 immatue + 1 mature scolex)

Tertian fevers

P. falciparum/ovale/vivax (every 48 hours, occurs on first and third days)

Portal HTN

Schistosoma japonicum/mansoni

3 manifestations: asymptomatic carriage in intestine; dysentery; extra-intestinal abscesses

Entamoeba histolyticum

Dx?

Cryptosporidium

Egg fertilized in soil --\> egg swallowed --\> hatches in body --\> eggs passed out in feces

Whipworm Ascaris (Remember: hookworm filariform larva directly penetrates skin)

Eggs or progrottid ingested by animal --\> oncospheres hatch --\> circulation --\> oncospheres form cysticerci in muscle --\> human eats animal --\> scolex attaches to intestine --\> eggs or gravid proglottid passed in feces

Tapeworm (Taenia solium, Taenium saginata)

Oocyst must be in enviornment for a while to become infectious

Toxoplasmosis (Toxoplasma gondii)

Tx for hypnozoites (P. ovale/P. vivax)

Primaquine (Check for G6PD deficiency!!)

How do you diagnose intestinal Taenia solium/saginata?

Eggs/progottids in feces

Leukopenia, anemia, thrombocytopenia

Lieshmaniasis

Most common protozoal intestinal infection

Giardia

Severe deformity

Mucocutaenous leishmaniasis (L. braziliensis - Latin America)

Reactivation

Toxoplasmosis (Toxoplasma gondii)

Blood meal --\> trypomastigotes become epimastigotes in vector's midgut --\> multiply in midgut --\> become metacyclic trypomastigotes in vector's hindgut --\> vector takes blood meal + passes trypomastigotes in feces --\> metacyclic trypomastigotes penetrates human cells and becomes amastigote --\> multiply intracellularly --\> transform into trypomastigotes and burst out of cells --\> taken up by another blood meal or reinfects other cells

T. cruzi

Which form of T. brucei is most rapidly fatal?

T. brucei rhodesiense (East African sleeping sickness)

What causes cerebral disease related to malaria?

Sticky RBCs (Decreased consciousness, seizures)

Filariform larva penetrates skin --\> circulatory system --\> travels to lung --\> trachea --\> swallowed --\> small intestine --\> become adults --\> eggs deposited in intestinal mucosa --\> rhabidiform larva either passed in feces or become filariform --\> filariform larva penetrate mucosa --\> circulatory system --\> lungs .....

Strongyloides (Remember autoinfection! Also the **larva** are diagnosed in stool, not eggs!)

Eggs in soil/feces --\> swallowed --\> hatch --\> larva attach to gut wall --\> eggs excreted in feces --\> embryonate in soil

Whipworm (Trichuriasis)

Vector of Leishmaniasis

Sandfly

Tissue cysts in sheep/pig --\> eaten by humans --\> pseudocysts in cells -OR- Tissue cysts in mice/birds --\> eaten by cat --\> fecal oocysts --\> ingested by human/sheep/pig --\> pseudocysts in human cells

Toxoplasmosis (Toxoplasma gondii)

Is Trichinosis transmissible between humans?

No (unless they're cannibals)

Ingestion of larva = GI infection Ingestion of eggs = cysts in various tissues

Tapeworm/cysticercosis (T. solium)

Undercooked meat, especially pork

Trichionosis (Trichinella spiralis) Tapeworm (Taenia solium/saginata)

Flask-shaped ulcers

Entamoeba histolyticum (Superficial ulcer looks small but spread out underneath)

Kinetoplast

T. brucei (Kinetoplast = circular DNA inside a mitochondrion)

Hypersensitivity to egg causes periportal fibrosis

S. japonicum/mansoni

Agent of elephantiasis

Wushceria bancrofti

Agents of visceral/cutaneous larva migrans

Toxocara canis, Toxocare cati (vs. Toxoplasma gondi = toxoplasmosis)

Larva form can produce cysts in various tissues

Tapeworm (T. solium, T. saginata)

How does T. cruzi cause cardiomyopathy? Megacolon and achalasia?

Cardiomyopathy via direct damage to myocytes Achalasia/megacolon via damage to autonomic ganglia

What symptoms would you expect in the patient from whom this egg was isolated?

Terminal hematuria, suprapubic pain (bladder CA) (Terminal spine = Schistosoma haematobium)

Cyst in definitive host, pseudocyst in intermediate host

Toxoplasmosis (Toxoplasma gondii) (Definitive host = cat; intermediate host = human, pig, sheep, bird, mouse)

Mature cyst contains thousands of protscolexes

Echinococcus granulosus (Hydatid cyst disease)

Female lives inside male's gynaecophoric canal

Schistosoma (paired adults)

Treatment = 2 doses of pyrental two weeks apart for whole family

Pinworm (Enterobius vermicularis)

Seropositive for life

Toxoplasmosis (Think: reactivation in AIDS)

No protective immunity

Entamoeba histolyticum Malaria

Flagellated protozoa

Giardia + trichomonas

Eggs hatch --\> release miracidia --\> penetrate snail tissue --\> form sporocysts --\> snail releases cercariae into water --\> cercariae lose tails and penetrate human skin becoming schistosomulae --\> get into circulation --\> migrate into portal blood --\> mature in the liver --\> paired adults migrate to mesenteric venules --\> lay eggs --\> circulate to liver/venous plexus of bladder or passed in stool

Schistosoma

What disease is caused by Schistosoma japincum/mansoni?

Portal HTN

Adults live in blood vessels draining the bladder or intestine

Schistosoma (Intestine = japonicum/mansoni; bladder = haematobium)

Severe diarrhea in AIDS patient Mild watery diarrhea in immunocompetent patient

Cryptosporidium

Dx?

Giardia

Malabsorption diarrhea

Giardia

Undulating membrane

T. brucei (African trypanosomiasis)

Liver, lung, brain abscesses

Entamoeba histolyticum

Dog eats sheep --\> infected --\> passes eggs via feces --\> ingest eggs --\> larva released in intestine --\> spread hematogenously --\> secrete membrane --\> inner part matures into germinal layer --\> produces protscolexes in various tissues

Echinococcus granulosus (Protscolexes = hydatid cyst)

Cysts ingested --\> trophozoites undergo binary fission in SI --\> encystation as trophozoites move toward LI --\> cysts passed in feces

Giardia

Painless bite

Chagas disease/reduviid bug

Neti pots

N. fowleri

Most common presentation is asymptomatic eosinophilia

Strongyloides

Mature cysts ingested --\> excystation in SI --\> released trophozoites travel to LI --\> produce cysts --\> cysts excreted in feces

Entamoeba histolyticum

Egg has clear outer shell

Hookworm (Necatur americanus, Ancylostoma duodenale)

Encysted larva ingested from muscle of animal --\> larva released in SI --\> adults deposit larva in mucosa --\> circulation --\> encysted larva in muscle

Trichinosis (Trichinella spiralis)

Anaphylaxis

Rupture of hydatid cyst (Echinococcus granulosus)

What are the Metazoan endoparasites?

Multicellular organisms = helminths (**Roundworms** [nematodes = Ascaris, Strongyloides] + **flatworms** [tapeworm = Taenia, fluke = Schistosoma])

Eggs flattened on one side

Pinworm (Enterobius vermicularis)

Baby born with hydrocephalus + generalized lymphadenopathy + hepatosplenomegaly + diffuse cerebral calcifications

Toxoplasmosis (Toxoplasma gondii)

Adults die after 5 years

Wuchereria bancrofti (Filariasis/elephantiasis; this causes calcification and inflammation that blocks lymphatics )

(T/F): The Whipworm eggs shed in feces are infectious

False - must embryonate in soil to become infectious

Not killed by chlorine

Cryptosporidium

Where does the adult form of this organism reside? Where would this egg be found inside the body?

Blood vessels draining the intestine Liver or intestines (Middle spine = Schistosoma mansoni)

Agent of cysticercosis

Taenia solium (tapeworm)

The metezoan life cycle consists of what 3 stages?

Egg Larva Adult

Local swelling at site of infection + fever + myalgia + rash; chronically - achalasia + cardiomyopathy + megacolon

T. cruzi (Chagas disease/American trypanosomiasis)

Cat is definitive host

Toxoplasmosis (Toxoplasma gondii) (Human, bird, mouse, sheep, and pig can be intermediate host)

Hyperinfection syndrome

Disseminated Strongyloides in immunocompromised host

Multiplies via binary fission = no cyst stage!

Trichomonas

Adult in lymphatics, microfilaria in blood stream

Wuchereria bancrofti (Elephantiasis)

Recurring fever + chancre + somnolence + coma

African trypanosomiasis (T. brucei)

Smallest of all tapeworms

Echinococcus granulosus (hydatid cysts)

What should you check for to ensure clearance of a tapeworm infection?

Scolex (If head still attached, worm can grow back)

Sx caused by immune response to egg deposition

Schistosoma

Active form = trophozoite Excreted, durable form = cyst

Entamoeba histolyticum

Matures in liver

Schistosoma

Swimming pools, water parks

Cryptosporidium

What causes fever, malaise, rigors with malaria?

RBC rupture (cyclic if untreated)

Host which maintains parasite in nature as a source for continued transmission

Reservoir

Resolves ~2 years if untreated

Whipworm

Cannot exist outside of the body because it cannot form cysts

Trichomonas

Romana's sign

Periorbital swelling due to T. cruzi/rdeuviid bug bite

What causes anemia with malaria infection?

RBC rupture

Adult in intestines, larva in muscle

Trichinosis (Trichinella spiralis)

Hepatosplenomegaly + spiking fevers + pancytopenia + hyperpigmented skin + superinfections

Visceral leishmaniasis

What causes the symptoms of cysticercosis?

Dying worms

Intermediate hosts of toxoplasmosis (Toxoplasma gondii)

Human, bird, mouse, pig, sheep

Agent of American typanosomiasis/Chagas disease?

T. cruzi (vector = reduviid bug)

Embryonated eggs ingested by human --\> larva hatch in SI --\> adults in lumen of cecum --\> Gravid female migrates to perianal region at night to lay eggs

Pinworm (Enterobius vermicularis)

Dx of this egg in feces?

Hookworm (Necatus americanus, Ancylostoma duodenale) (Clear shell around egg!!)

No digestive tract

Tapeworms (T. solium, T. saginata)

Tx with metronidazole for symptomatic infection or paromycin to eliminate luminal carriage

Entamoeba histolyticum

Cutaneous leishmaniasis symptoms

Ulcer at sandfly blood meal site

Host in which development and possibly asexual reproduction occurs but not sexual reproduction

Intermediate host

Reinfection is very common

Whipworm

Common sx are pneumonitis and intestinal obstruction

Ascariasis

Respiratory failure + gram negative rod sepsis + acute abdomen

Hyperinfection syndrome (Strongyloides in immunocompromised host)

Brain cysts + seizures

Neurocysticercosis (Taenia solium)

VSG

T. brucei (Variable surface glycoprotein - accounts for intermittent fever + ability to evade immune system; only one glycoprotein expressed at a time)

Transmitted by mosquitos

Malaria Wuchereria bancrofti (filariasis/elephantiasis)

Agent of hydatid cyst disease

Echinococcus granulosus

Hematuria, bladder cancer

Schistosoma haematobium

Sheep dogs

Echincoccus granulosus (Hydatid cyst)

Cercariae

Infective form of Schistosoma in humans

Dysentery + RUQ pain

Entamoeba histolyticum

Survival \< 1%

N. fowleri (Primary amebic meningoencephalitis)

HIV/AIDS patients with low CD4+ and visual complaints

Toxoplasmosis (Toxoplasma gondii)

Prevention by filtering water supplies

Cryptosporidium

Anopholes mosquito

Malaria

Dx?

Malaria ring form

Parasites Flashcards

(187 cards)