Parasite Type Appearance of adult Appearance Mode/stage of Intermed. Reserv Egg loc. Larvae loc. Adult loc.
of egg infection host host
Enterobius Pinworm Non-seg; alae in X Embry., Ingest eggs or None None Anus, laid at Sm. Int Tr. & desc.
vermicularis (roundworm) section; fem: 1cm, football larvae crawl night colon, rectum
nematode straight; male: 4mm, back in thru
copulatory spicule, curly; anus
Cuticle,full GI,NS
Trichuris Whipworm Non-seg; thick front, thin Oval, embry, Ingest egg None none Feces, must Sm int, b/w epi Tr & desc
trichiura (roundworm) tail, male curved body; 3- dark, thick embry to be & lam. propria colon, imbed in
nematode 5cm edge infectious columnar cells
Ascaris Roundworm Non-seg; cuticle, 15cm, Contains 2nd Ingest egg Maybe Feces, embry in Pen. Cap to Upper sm int
lumbriocoides nematode long, skinny stage larv, pigs soil liver to heart to
round, lungs to trach.
splotchy coat
Toxocara canis Roundworm Ingest egg Dog/ca Int to brain/eye
nematode t
Necator Hookworm Rounded cutting plates; Thin outer Filariform Feces, devel to Rhab larv in Sm int, sucks
americanus nematode 1.5cm, male: cop bursa coat, clump larvae pen fil larv in soil soil, fil thru blood thru wall,
(hand); fem: pointy tail; in middle, skin skin, Cap to releases anti-
long, slender; short embry. lungs to trach. coags
esophagus,
Ancylostoma Hookworm Cutting teeth, 2cm, male: Thin outer Filariform feces, devel to Cap to lungs to Sm int sucks
duodenale nematode cop. bursa (hand); fem: coat, clump larvae pen fil larv in soil trach blood thru wall,
pointy tail;1cm; short in middle, skin, or ingest releases anti-
esophagus embry larv coags
Strongyloides nematode Fem: 2mm, long, slender; Not seen b/c Filar. Larv Dog, Hatch in sm. Int Cap to lung to Upper s m int,
stercoralis no parasitic male hatch in pen skin or fil primate into 1st stage trach in lam prop
intestine larv pen colon s, also larvae
to blood - free-
autoinfect living
in soil
Taenia saginata Tapeworm 8-10m, flat, seg, scolex + Thick rim, Cysticercus None Hatch in cow Cow tissue Upper sm int
cestode proglottids, tegument, 4 embry, can’t ingested w/ sm. int, go to ingested to sm
suckers on scolex tell which raw beef tissues, dev to int
taenia cysticerci
Taenia solium Tapeworm 10m, flat, seg, scolex + Thick rim, Cysticercus None Hatch in pig sm Pig tissue Upper sm int
cestode proglottids, teg, 4 suckers embry, can’t ingested w/ int, go to ingested to sm
+ 2 rows of hooklets tell which raw pork tissues, dev to int
taenia cysticerci
Cystircercosis Taenia No adult,egg to Thick rim, t. solium eggs none Ingested from oncospherepen
solium oncosphere to cysticercus embry, can’t ingested or feces or regurg, int wall to
cysterci only tell which regurgitated hatch in sm int blood to tissue,
taenia to stomach become cyst. In
brain, eye,
muscle
Echinococcus No adults in humans. Ingest embry. Dogs are Feces of dog, oncospherepen No adults in
granulosus 5mm, scolex + 3 segs, 4 egg definitive host; hatch in human int wall to humans
suckers + hooks humans, sheep - sm int blood to tissue
intermed hosts (oft. liver),
become hydatid
cyst, dev
protoscoleces
Parasite Type Appearance of adult Appearance Mode/stage of Intermed. Reserv Egg loc. Larvae loc. Adult loc.
of egg infection host host
Schistosoma Trematode Fem:15mm; male 1cm; Oval, lateral Cercariae Snail Monke Eggs in sm.int Miracidium to Inf mesenteric
mansoni blind gut, eat globin from spine, 300 enter skin y, wall, pre-sin cercariae in venules
Hgb, male spoons female, per day baboon caps in liver, snail;
ant & vent suckers, spleen, lung Schistosomula
tegument exist feces, to blood to lung
hatch fresh to liver
water,
miracidium in
snail
Schistosoma Trematode Fem:15mm; male 1cm; Round, no Cercariae Snail None Eggs in sm. int, Miracidium to Sup. mesenteric
japonicum blind gut, eat globin from spine, 1500- enter skin pre-sin caps in cercariae in venules, chor
Hgb, male spoons female, 3000 per day liver, spleen, snail; plex, spinal ven
ant & vent suckers, lung; exist Schistosomula
tegument feces, hatch to blood to lung
fresh to liver
water,become
miracidium in
snail
Schistosoma Trematode Fem:15mm; male 1cm; Oval, Cercariae Snail Water Eggs in Miracidium to Bladder venous
haematobium blind gut, eat globin from terminal enter skin buffalo bladder, ureter cercariae in plexus
Hgb, male spoons female, spine , walls, exist snail;
ant & vent suckers, cow,pi urine, hatch Schistosomula
tegument g fresh water, to blood to lung
miracidium in to liver
snail
Plasmodium protozoa Mat troph: RBC enlarged, Gametocytes Sporoz. Man is intermed, Sporos go to Immat troph
vivax pale, Schuffner’s dots; lg large, circ. or Injected into defin is mosquito liver, enter cell, matures in
single mass chrom, irreg oval skin by form schiz, periph blood,
cytoplasm, brown female divide to prod makes schiz,
pigment, parasite fills Anopheles meroz, go enter meroz, inf more
cell; schizont: 12-24 mosquito RBCs cells
meroz.
Plasmodium protozoa Mat troph: RBC crenated, Sporoz. Man is intermed, Sporos go to Immat troph
ovale nl size, not totally full of Injected into defin is mosquite liver, enter cell, matures in
parasite skin by form schiz, periph blood,
female divide to prod makes schiz,
Anopheles meroz, go enter meroz, inf more
mosquito RBCs cells
Plasmodium protozoa Mat troph: RBC nl size, Gametocytes Sporoz. Man is intermed, Gametocytes in Sporos go to Caps of internal
falciparum color light cytoplasm, crescent- Injected into defin is mosquite sequestered liver, enter cell, organs, no mat
double infection; shaped skin by sites form schiz, trophs in periph
schizont: 8-24 meroz female divide to prod blood exc w/
Anopheles meroz, go enter heavy inf.
mosquito RBCs in deep
vasc not periph
bld
Plasmodium protozoa Mat troph: RBC nl or sm, Gametocytes Sporoz. Man is intermed, Sporos go to Immat troph
malariae dark, elongate chrom, large, oval or Injected into defin is mosquite liver, enter cell, matures in
dense cytoplasm, band circ; dark skin by form schiz, periph blood,
forms, pigment dark & pigment female divide to prod makes schiz,
coarse; schizont: 6-12 Anopheles meroz, go enter meroz, inf more
meroz, “Rosette” mosquito RBCs cells
Parasite Type Appearance of adult Appearance Mode/stage of Intermed. Reserv Egg loc. Larvae loc. Adult loc.
of egg infection host host
Toxoplasma Protozoa, Pseudocysts: collection of Double outer Ingest oocyst Man, many other Made in cat Sporos in sm Tachyz
gondii obligate bradyz, inside host cell, ring, inner in cat feces, mammals, are epithelial cells int go thru wall, becomes
intracellular can be anywhere, often in ring filled or intermed, defin is by fusing of ingested by bradyz, org into
brain, “rosettes” pseudocysts cat gametocytes to macs, become pseudocyst,
in infected form oocyst, tachyz, rupture dormant
meat, or trans- out in cat’s mac, go to
placental feces other cells,
repeat
Pneumocystis
carinii
Giardia lamblia Protozoa, Trophoz: pear shaped, No eggs Ingest cysts beaver No eggs Excystation in Sm int, trophoz
aerotolerant motile 15 m, 8 flagella, from feces sm int to 2 reencyst, pass
anaerobic binucleate, 2 median trophoz, attach out with feces
bodies, no mito, perox, to epi, binary
some have dsRNA virus; fision
cyst: oval, 4 nuclei
Entamoeba Protozoa, Trophoz: motile, 25 m, No eggs Ingest cysts none No eggs Excystation in Sm int, trophoz
histolytica aerotolerant 1 nucleus, lysosomes, from feces sm int to 4 reencyst, or can
anaerobic crypton (remnant mito); trophoz, divide go to liver or
cyst: 12 m, up to 4 to 8, peristals to brain after int.
nuclei, some have colon, attach to wall
chromatoidal bar of epis, lyse them, penetration,
ribosomes divide by cysts pass out
binary fision with feces
Cryptosporidiu protozoa cyst: thick walled, 4 No eggs Ingest oocysts Sheep, No eggs Excyst in sm sporoz to type I
m parvum sporoz; meront: contains cows,bi int, to 4 sporoz, meront to 4
sporoz, make gamonts rds, attach to epis, meroz released,
rodents microvilli fuse attack new epi
,primat & elong, to Type II
es surround meronts
sporoz
Parasite Sex Length Detection Who at Pathology Endemic Treatment Comm.. Other
of risk areas prevention
cycle
Enterobius M&f, in colon 4-6 Sticky tape for kids Mild inflam, itching Pyrantel none
vermicularis wks eggs pamoate or meb
or alb, repeat
dose 2x
Trichuris M&f, in colon 3 mos Eggs in stool, kids Prolapsed rectum, Humid, Meb or alb Sanitation, Eggs survive in
trichiura Charcot-Leyden colitis, low IQ, warm but soil up to 3 years,
crystals seen in ?anemia reinfection Charcot-Leyden
stool common crystals seen in
stool
Ascaris M&f, in sm int 30-70 Eggs in stool Kids Pneumonitis, tropics Alb b/c extra- Sanitation, Eggs survive in
lumbriocoides days hepat/bil obstruct., GI stage soil up to 3 years
Cognitive, growth
impaired
Toxocara canis Not in stool, Glaucoma, eosin,
kids Steroids & Avoid dog
ELISA hep/splenmeg, thiobendazole poop
pneum
Necator M&f in sm int, 2 mos Eggs in stool, Kids,el Anemia, dermatitis Tropics, Alb + iron supp San, reinfect. Blood loss when
americanus 5-10000 eggs can’t disting. B/w derly China common they change
per day hooks location in gut.
Rhab long buccal
cavity
Ancylostoma M&f in sm int, 2 mos Eggs in stool, Kids, More severe than Tropics Alb + iron supp San, reinfect Blood loss when
duodenale 10-30000 eggs can’t disting. B/w elderly nec. Anemia, common they change
per day hooks dermatitis location in gut,
rhab long buccal
cavity
Strongyloides F only, parthen. 1 mo Larv in stool, Kids, Hyperinfect from Tropics, Thiabendazole, Rhab short buccal
stercoralis In sm int short bucc, notch elderly, autoinf causes App mtns ivermectin cavity; hyperinf
tail, do several imm.co ectopic CNS abcess, common in
tests, string test mprom bact. Sepsis b/c of immunocompromi
ised migrating larvae, sed people
diarrhea, dec growth,
malabsorption
Taenia saginata Each has m&f 3 mos Proglottids in Adult worms no Praziquantel, San, meat
organs but stool or on bed, pathology must get scolex cooked or
usually X mate >15 branches in out frozen
b/w segs, progravid or do
detach, hatch in sticky tape for
intermed host eggs but only
sm int know its taenia
Taenia solium Each has m&f 3 mos Proglottids in Adult worm no Praziquantel + San, meat
organs but stool or on bed, pathology antiemetic, cooked or
usually X mate <12 branches in must get scolex frozen
b/w segs, progravid or do out
detach, hatch in sticky tape for
intermed host eggs but only
sm int know its taenia
Cystircercosis Grow 3 x-ray extremities, Path of space-occ Praziquantel + San,
wks sticky tape if adult lesion, seizures, steroids for vaccines
then worms pres, shadows in eye inflam.
stop ELISA
Echinococcus Alive Hooks in sputum, shephe Anaphyl if rupture, Surgery – very Don’t feed No biopsy b/c of
granulosus for ELISA of hydatid rds spread; space-occ carefully, alb dogs inf metastasis
mos to fluid lesion meat
years
Parasite Sex Length Detection Who at Pathology Endemic Treatment Comm.. Other
of risk areas prevention
cycle
Schistosoma M&f in liver, Few Eggs in stool, Egg depos. in int & Near praziquantel San, but
mansoni eggs in mes days rectal snip, ELISA liver- fibrosis, dams, reinf.
vessels, TNF granuloma, GI fresh
required for hemor, pipe stem water
eggs to survive fibrosis, portal HT,
hep/splmegaly; bact
assoc. with adult,
Katayama fever, cor
pulmonale
Schistosoma M&f in liver, Few Eggs in stool, Egg depos in int & Near praziquantel San, but
japonicum eggs in mes. days rectal snip, ELISA liver – fibrosis, dams, reinf
vessels, , TNF granuloma, GI fresh
required for hemor, pipe stem water
eggs to survive fibrosis, portal HT,
hep/splmegaly; bact
assoc. with adult,
Katayama fever, cor
pulmonale
Schistosoma M&f in liver, Few Eggs in urine, Egg depos in bladder Near praziquantel San, but
haematobium eggs in bladder. days ELISA – fibrosis, dams, reinf
vessels, , TNF granuloma, fresh
required for calcification, water
eggs to survive hematuria, sq cell
carc.; bact assoc.
with adult
Plasmodium Asexual in liver 10 All stages seen in Adults Anemia, fever, DIC, tropics Quinines (if not Kill mosq, Relapsing, 10000
vivax cells and blood days blood smear, and diarrhea resistant) prophylaxis meroz per schiz
schizonts, enlarged stippled kids 1- hep/splenomeg, artemisinum or
sexual RBCs 5, preg hemolysis, renal antibiotics,
gametocytes women failure Primaquine for
only in mosq liver
gut hypnozoites
Plasmodium Asexual in liver 11 All stages in Adults Anemia, fever, DIC, Africa, Quinines (if not Kill mosq, Relapsing, 15000
ovale cells and blood days smear and diarrhea W.Pacif. resistant) prophylaxis meroz per schiz
schizonts, kids 1- hep/splenomeg, artemisinum or
sexual 5, preg hemolysis, renal antibiotics
gametocytes women failure Primaquine for
only in mosq liver
gut hypnozoites
Plasmodium Asexual in liver 8 days Signet ring only in Adults Anemia, fever, DIC, Africa Quinines (if not Kill mosq, Most prevalent &
falciparum cells and blood blood smear, must and diarrhea resistant) prophylaxis worst form, non-
schizonts, find gametocytes kids 1- hep/splenomeg, artemisinum or relapsing, RBCs
sexual for definitive 5, preg hemolysis, cerebral antibiotics have knobs that
gametocytes diagnosis women malaria, renal failure, bind endothelium,
only in mosq coma (TNF incuces 30000 meroz per
gut NO anaphylaxis) schiz
Plasmodium Asexual in liver 18 Same size RBCs, Adults Anemia, fever, DIC, World- Quinines (if not Kill mosq, Non-relapsing,
malariae cells and blood days all stages in smear and diarrhea wide resistant) prophylaxis 2000 meroz per
schizonts, kids 1- hep/splenomeg, artemisinum or schiz
sexual 5, preg hemolysis, renal antibiotics
gametocytes women failure
only in mosq
gut
Parasite Sex Length Detection Who at Pathology Endemic Treatment Comm.. Other
of risk areas prevention
cycle
Toxoplasma Asexual in PCR, look for Fetus, CNS cysts, World- Pyrimethamine Cook meat, Tachyz. prevents
gondii macs and other antibodies imm.co chorioretinitis in wide & sulfadiazine, avoid cat fusion of
cells, sexual in mprom fetus, hydrocephaly, spiramycin for poop, preg lysosome w/
cats ised most acquired inf. pregnant tests parasitic vesicle in
(pseudocyst asymptomatic, some women mac, IL-12
ruptures in lymphadenopathy upregulated to
sm.int, bradyz fight infection
invade epis,
become meroz,
then gamets,
which fuse to
oocyst, out w/
poop,
sporulates to
make sporoz
Pneumocystis
carinii
Giardia lamblia Binary fision in Trophoz or cyst in Day Diarrhea, steatorrhea, metronidazole sanitation environmental
sm int stool 3 times, or care malabsorption, resistance of cyst
ELISA for kids flattened, fused villi
antigen, string test of sm. int
Entamoeba Binary fision in Antigen in stool or Ulcer, diarrhea, Metronidazole sanitation Need galactose
histolytica sm int and PCR, looks same dysentery, colitis, and iodoquinol moiety on epi cells
colon as enamoeba abd pain, ameboma, to attach, Charcot-
dispar in stool so liver abcess, lung, Leyden crystals
need PCR, occasionally brain seen in stool,
Charcot-Leyden environmental
crystals seen in resistance of cyst,
stool needs ILs to
survive
Cryptosporidiu Type II meronts Up to 1 PCR or acid fast- Kids, Diarrhea (lots), No drugs sanitation Looks like
m parvum make macro & mo stained oocytes in imm.su cramps cyclospora
microgamonts, stool pp. cayetanensis
they fuse to which is treatable
make thick
walled oocyst,
sporulates in
colon to make 4
sporoz, or
oocyst passes in
feces; also can
make thin
walled oocyst
that excyst and
autoinf.
Drug Mechanisms:
Quinines: inhibit stacking enzyme that deposits haemozoin
Praziquantel: blocks Ca2+ channels
Mebendazole/Albendazole: blocks microtubule polymerization
Metronidazole: interferes with anaerobic metabolism
Info frequently tested on past exams:
Parasitic stage of entry in humans:
1. Egg – E. vermicularis, T. trichiura, A. lumbricoides, T. canis, cysticercosis (via T. solium), E. granulosus
2. Cyst – T. gondii, G. lamblia, E. histolytica, C. parvum
3. Cercaria – schistosomes, T. saginata, T. solium
4. Larvae – N. americanus, A. duodenale, S. stercoralis, E. vermicularis (crawls back in anus)
Mode of transmission:
1. Fecal-oral: E. granulosus, T. canis, T. trichiura, cystercircosis, A. lumbricoides, C. parvum, G. lamblia, E. histolytica, T.
saginata, T. solium, A. duodenale (more commonly penetrates skin)
2. Skin penetration: schistosomes, N. americanus, A. duodenale, S. stercoralis, malaria (via mosquito)
3. Raw meat: T. solium, T. saginata, T. gondii
Drugs:
1. Praziquantel: T. saginata, T. solium, schistosomes, cysticercosis
2. Mebendazole: E. vermicularis, T. trichiura
3. Albendazole: A. lumbricoides, E. granulosus, N. americanus, A. duodenale
4. Thiobendazole: T. canis, S. stercoralis (with ivermectin)
5. Quinines: all malarias
6. Primaquine: P. ovale, P. vivax
7. Spiramycin: T. gondii (in pregnant women)
8. Metronidazole: E. histolytica, G. lamblia
9. Pyrimethamine & sulfadiazine: T. gondii
10. Untreatable with drugs: C. parvum
Method of detection:
1. Antibody (ELISA): cysticercosis (T. solium), E. granulosus, T. canis, G. lamblia, T. gondii, schistosomes
2. Stool: S. stercoralis, N. americanus, A. duodenale, T. trichiura, A. lumbricoides, S. mansoni, S. japonicum
3. Rectal snip: S. mansoni, S. japonicum
4. Sticky tape: E. vermicularis, T. saginata, T. solium
5. PCR: T. gondii, E. histolytica, C. parvum
6. String test: S. stercoralis, G. lamblia
Symptoms:
1. Anemia: malaria, N. americanus, A. duodenale
2. Diarrhea: G. lamblia, malarias, E. histolytica, C. parvum, S. stercoralis
3. Hydrocephalus: T. gondii
4. Hydatid cyst: E. granulosus
5. Malabsorption: S. stercoralis, G. lamblia
6. Hepatosplenomegaly: T. canis, S. mansoni, S. japonicum
Immuno stuff:
1. Much worse in immunocompromised: C. parvum, S. stercoralis, T. gondii, A. lumbricoides
2. Needs TNF for egg production: schistosomes
3. Charcot-Leyden crystals seen from eosinophilia: E. histolytica, T. trichiura
4. Needs IL for survival: E. histolytica
Mechanisms:
1. Needs galactose moiety on ECs: E. histolytica
2. Prevents lysosomal fusion: T. gondii
3. Hides from immune system: A. schwarzenegger, schistosomes
4. Latent liver stage: P. vivax, P. ovale
5. Environmental resistance: A. lumbricoides, T. trichiura, G. lamblia, E. histolytica
6. Enclosed in columnar cell membrane: C. parvum