Parasitology

Question 1

Entamoeba histolytica

Answer 1

10-20 um
infective/diagnostic stage = cyst
Troph: granular cytoplasm, *Evenly arranged chromatin in peripheral of nucleus), *Small compact central karyosome, May have ingested RBCs (Dysentery), unidirectional
Cyst: 4 nuclei, chromatoidal bar
Disease: invade mucosa, flask-shaped ulcer, ab.pain, frequent BMs
TX: metronidazole

Question 2

Entamoeba hartmanni

Answer 2

5-10 um
infective/diagnostic stage = cyst
Troph: nondirectional, no RBCs ingested
Cyst: up to 4 nuclei
DIsease: non pathogenic
TX: metronidazole

Question 3

Entamoeba coli

Answer 3

20-40 um
infective/diagnostic stage = cyst
Trop: vacuoles w/ yeast, *eccentric karyosome, *clumped/irregular chromatin
Cyst: up to 8 nuclei, splinter-shaped chromatoidal bars
Disease: non pathogenic
TX: metronidazole

Question 4

Endolimax nana

Answer 4

Infective/diagnosic stage = cyst
Troph = *no peripheral chromatin, *large karyosome
Cyst = 4 nuclei, no chromatoidal bars
Disease: non pathogen
TX: metronidazole

Question 5

Blastocystis hominis

Answer 5

Infective/diagnostic stage = cyst
Cyst: large central body (stains dark), pushes nuclei to the edge
Disease: watery diarrhea, ab. pain, flatulence
TX: metronidazole

Question 6

Iodamoeba butschlii

Answer 6

Infective/diagnostic stage = Cyst
Troph: active motility, granular cytoplasm with large vacuole, large/eccentric karyosome, “basket” appearance
Disease: non pathogenic

Question 7

Dientamoeba fragilis

Answer 7

*NO cyst stage, amoeba-flagelate
Troph: two nuclei, *fragmented karyosome, no peripheral chromatin, vacuoles with ingested debris
Disease: diarrhea, ab. pain
Related to bad hygiene
TX: metronidazole

Question 8

Acanthamoeba

Answer 8

Related to pools, water, AC units, contact lens hygiene
Pseudopods
Granulomatous Amoebic Encephalitis (GAE): headaches, neurological defects, keratitis/corneal ulcers, death
TX: Polymixin B, Clotrimazole

Question 9

Naegleria fowleri

Answer 9

Related to water, pools, aquariums
Infective Stage = flagellate
Diagnostic Stage = Troph
Primary Amoebic Meningoencephalitis (PAM): Infection of meninges, enters through nasal cavity and migrate to brain via olfactory nerve, death by cardio-respiratory arrest
Diagnosis: CSF has decreased glucose/ increased protein, flagellate seen in CSF

Question 10

Giardia lamblia

Answer 10

Intestinal flagellate
Infective Stage = Cyst (through food/water)
Diagnostic = Cyst AND troph
Cyst: 4 nuclei, median bodies
Troph: 4 pairs of flagella, adhesion disk, 2 nuclei, 2 axonemes, 2 median bodies
Disease: feeds on mucous in duodenum; ab. pain, flatulence, diarrhea with NO BLOOD
TX: Quinacrine (Atabrine)

Question 11

Trichomonas vaginalis

Answer 11

No cyst stage
Troph: undulating membrane
Women: ab. pain, vaginitis, discharge
TX: metronidazole

Question 12

Chilomastix mesnili

Answer 12

Infective Stage = Cyst
Cyst: lemon shaped with hyaline bleb, curved fibril (“shepard hook”)
Troph: pear shaped, 1 nucleus, oral groove
Disease: non pathogen

Question 13

Balantidium coli

Answer 13

Ciliate
Hogs are resevoir
Infective/Diagnostic Stage = Cyst
Troph: oval with short cilia
TX: metronidazole, tetracycline

Question 14

Plasmodium species

Answer 14

Definitive host = mosquito
Intermediate host = human
Infective stage = sporozoite
Diagnostic stage = ring form, gametocyte

Question 15

Plasmodium falciparum

Answer 15

High parasitemia
Disease: Tertian Fever(48 hour), Fever spikes, decreased BP
Diagnosis: multiple rings, RBCs not enlarged, applique forms, banana-shaped gametocyte

Question 16

Plasmodium malariae

Answer 16

Disease: Quartan Fever ( 72 hours)
Diagnosis: RBCs not enlarged, no multiple rings, “birds eye” rings, “band form” trophzoites, “rosette” schizont

Question 17

Plasmodium vivax

Answer 17

Disease: Tertian Fever (48 hr)
Diagnosis: RBCs enlarged, Schuffner’s Dots present, large rings (>1/3 of cell), amoeboid trophs, schizonts have 8-12 merozoites

Question 18

Plasmodium ovale

Answer 18

Disease: Tertian Fever (48 hour)
Diagnosis: RBCs enlarged, Schuffner’s Dots present, oval RBCs with fimbrated edge.

Question 19

Babesia

Answer 19

B. microti = Northeast US
B. divergens = Europe
B. duncani = WA and CA
Diagnosis: High parasitemia, multiple ring forms per RBC, ring forms have clear center, “maltese cross”, extracellular ring forms
Life Cycle: Two hosts (tick and mouse), humans infected by Ixodes Tick

Question 20

Toxoplasma gondii

Answer 20

Life Cycle: Cats are definitive hosts (humans infected by cats)
Disease: affects immunocompromised, flu-like, lymphadenopathy, congenital (can cause CNS problems in baby if they get it from their mother)

Question 21

Cryptosporidium

Answer 21

Infective/Diagnostic stage = oocyst
Diagnosis: round oocysts, 3-6 um, pink/red on Modified Acid Fast Stain
Disease: diarrhea, dehydration, immunocompromised (AIDS)

Question 22

Cystoiospora belli

Answer 22

Infective/Diagnostic stage = oocyst
Diagnosis: pink/red in Modified Acid Fast, can be seen in wet mount, 25-30 um
Disease: affects immunocompromised, non-bloody diarrhea, weight loss

Question 23

Microsporidia

Answer 23

Tiny (0.8-4.0 um)
stain red/pink with trichrome blue stain, has a belt-like stripe
affects immunocompromised

Question 24

Nematode

Answer 24

Round worms

TX: Albendazole. mebendazole

Question 25

Enterobius vermicularis

Answer 25

“Pin worm”
Diagnosis: Pin worm paddle is best collected right after waking, humans are their only host
Disease: Ab. pain, pruritus
Infective/Diagnostic stage = egg
Life Cycle: female produces eggs and lays them around anus

Question 26

Trichus trichura

Answer 26

“Whip Worm”
(Can co infect with Ascaris)
Infective/Diagnostic stage = embryonated (barrel) egg
Life Cycle: egg is ingested, larva mate and produce eggs, eggs found in cecum (large intestine)
Disease: diarrhea, gastrointestinal pain, rectal prolapse.
Egg = barrel shaped with polar plugs

Question 27

Ascaris lumbricoides

Answer 27

“large intestinal roundworm”
Infective/Diagnostic stage = embryonated egg
Life Cycle: Ingest embyronated egg, lava hatch and circulate (can go to lungs, cough and swallow), mates in intestine, eggs passed
Diagnosis: Bumpy, thick walled egg with large cellular mass, largest nematode, spread through food/water
Disease: high worm burden can cause intestinal obstruction, pulmonary symptoms

Question 28

Hookworms

Answer 28

Found in SMALL intestine
Ancyclostoma duodenale: Middle East, teeth for attachment
Necator americanus= North American, cutting plate
Infective stage = lavra
Diagnostic stage = egg and adult worm (can’t differentiate based on eggs)
Life Cycle: Larva penatrates skin, circulates (can go to lungs), mates/produces eggs, eggs passed
Disease: “ground itch”, blood loss

Question 29

Strongyloides stercoralis

Answer 29

“Threadworm”
Infective/Diagnostic Stage: larva
Life Cycle: step on worm (penetrates skin), circulates (can go to lungs), female lays eggs in intestinal tract, EGGS HATCH IN GUT, larva passed, male/female mate outside of body, eggs hatch into larva, human steps on larva
Disease: cutaneous, pulmonary, intestinal
SHORT BUCCAL CAVITY IN RHABDITIFORM

Question 30

Trichinella spiralis

Answer 30

“Trichinellosis”
Life Cycle: Ingest larva (animal), encysts in muscles, we eat the meat, female produces eggs in intestine, encysts in human muscles
Disease: myalgia, myocarditis, facial edema; must do muscle biopsy

Question 31

Dracunculus medinensis

Answer 31

“Guinea Worm” (Africa)
Life Cycle: larva in water, ingested by copepods, human drinks water, larva mature in human, adult female migrates to feet/ankle, blisters form and release female, female lays eggs in water
TX: pull it out

Question 32

Cestodes

Answer 32

Tape worms
TX: Praziquantel
Definitive host = humans

Question 33

Taenia solium

Answer 33

“pork tape worm”
can have brain cysticercus
Life Cycle: cysticercus ingested from raw pork, attach to intestine and release gravid proglottids, eggs hatch and pass, pigs eat eggs
Can not differentiate based on eggs

scolex is rostellum with ring of hooklets

Question 34

Taenia sanguinata

Answer 34

“beef tapeworm”
raw beef
NO brain cysticercus

scolex is flat/rounded

Question 35

Diphyllobothrium latum

Answer 35

“broad fish tapeworm”
raw fish
Infective stage = Pleroceroid (in fish muscle)
Diagnostic stage = egg
life cycle: pleroceroid is in fish muscle, we eat fish, grows in intestinal tract, egg goes into water, embryo hatches in water, enters crustation, fish eats crustation, we eat fish
Disease: Gefilte Fish “Jewish Housewife Disease”, egg has operculum WITHOUT shoulders with abopercular knob
Diagnosis: diarrhea, vomit

proglottids are broader than long

Question 36

Hymenolepsis nana

Answer 36

“dwarf tape worm”
Infective/Diagnostic stage = egg
Life Cycle: egg ingested by insect, rodent eats insect, humans ingest/inhale eggs
Disease: light, ab. pain, diarrhea
Diagnosis: 6-hooked embryo with POLAR FILAMENTS

Question 37

Hymenolepsis diminuta

Answer 37

“rat tape worm”

Same as D. nana, but egg has NO polar filiments

Question 38

Trematodes

Answer 38

Flukes
TX: Praziquantal
Infective stage = larva
Diagnostic stage = egg
Life Cycle: Human stands in water, cercaria (larva) attaches to skin and burrows in, circulates (bladder/gut), eggs passed in stool, eggs goes into water, ingested by snail, burrows out of snail and into water

Question 39

Shistosoma

Answer 39

“swimmers itch”
Mansoni = South America, Africa, Middle East ; lateral spine
Japonicum = China, Japan ; small/less conspicuous spine
Haematobium = Africa; large/straight spine

Question 40

Paragonimus westermani

Answer 40

“lung fluke”
Infective stage = larva
Diagnostic stage = egg
Life Cycle: humans eats crustation, ingests larva (cercaria), develops in gut, passes, hatches in water, enters snail, crustation eats snail
Diagnosis: egg has operculum with SHOULDERS

Question 41

Fasciolopsis bucki

Answer 41

"large intestinal fluke"
Watercress, water chestnuts
SMALL INTESTINE
Diagnostic stage = egg
Small/indistinct operculum

Question 42

Fasciola hepatica

Answer 42

“Sheep live fluke”
Life Cycle: Humans eat watercress, parasite grows in liver/gall bladder, eggs oass, miracidium enters snail, becomes cercaria, enters plant
Found in liver, can obstruct liver ducts
Disease: URQ pain, high IgG/IgM, jaundice, biliary obstruction, hepatomegaly
Can not speciate based on eggs, so look at where the adult is located.

Question 43

Clonorchis sinensis

Answer 43

“Chinese/Oriental Live Fluke”
Life Cycle: We pass egg, it hates and lives in snail, fish eat cercaria, we eat fish
Diagnosis: “urn shaped” eggs, operculum WITH SHOULDERS, knob at opposite end.