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128 Cards in this Set

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what are the roundworms (nematodes) you get by ingestion?

Enterobius vermicularis
Ascaris lumbricoides
Trichuris trichiura
Toxocara canis/cati
Trichinella spiralis
Anisakis spp.
Dracunculus medinensis

what roundworm causes pinworms?
Enterobius vermicularis
what roundworm causes Ascariasis?

Ascaris lumbricoides

what nematode causes whipworm?
Trichuris trichiura
what nematode causes visceral larva migrans?
Toxocara canis/cati
Trichinella spiralis
Anisakis spp.
Dracunculus medinensis
what nematode causes trichinosis?
Trichinella spiralis
what nematode causes Anisakiasis/herring disease?
Anisakis spp.
what nematode is the Guinea fire worm (fiery serpent)?
Dracunculus medinensis
what roundworm infecs are acquired via the skin?
Necator americanus & Ancylostoma duodnale
Ancylostoma caninum & A. braziliense
Strongyloides stercoralis
Wuchereria bancrofti
Loa Loa
Onchocerca volvulus
Dirofilaria immitis
which roundworms are the intestinal worms?
Necator americanus & Ancylostoma duodnale
what roundworms cause cutaneous larva migrans?
Ancylostoma caninum & A. braziliense
what roundworm causes Strongyloidosis?
Strongyloides stercoralis
what nematode causes filariasis --> elephantiasis?
Wuchereria bancrofti
what nematode is the eye worm and causes calibar swellings?
Loa Loa
what nematode is responsible for river blindness?
Onchocerca volvulus
(W. Africa)
what nematode causes dog heart worm (coin lesion)?
Dirofilaria immitis
what nematode causes dog heart worm (coin lesion)?
Dirofilaria immitis
where can you get Toxocara canis/cati?
Dog & cat ASCARID worms
(10-12 cm long) shed eggs in
feces, ending up in the dirt
how does Toxocara become infectious?
Eggs embryonate in soil for 2-3 weeks; thereafter they are infectious for dogs (& cats) & humans
how is Toxocara canis/catis transmitted?
Eggs INGESTED mainly by kids 1-4 yrs old, who indulge in PICA (= eating dirt, etc)
what happens once Toxocara is ingested?
When ingested by humans --> larvae penetrate human gut, reach blood stream, then migrate as larvae to various human tissues; they do not develop beyond migrating larvae
are Toxocara canis infections common?
Infection rate in the 50 million dogs inhabiting the US is great; > 80% of puppies & 20% of older dogs involved.
what age grp shows clinical manifestations of Toxocara canis?
Clinical manifestations occur mostly among children 1 - 6 yrs old.
why do ppl get disease from Toxocara canis infections?
Disease results from organ invasion by larvae via blood stream & hypersensitivity to larval antigens
what organ systems are affected in Toxocara canis infections?
Liver, lungs, heart, skeletal muscle, brain, eye & skin involved most frequently
what kind of damage can Toxocara canis larvae cause?
Larvae cause necrosis, bleeding, formation of eosinophilic granulomas & fibrosis
what are the symptoms of intense Toxocara canis infec?
Children with more intense infection may have fever & big liver
More seriously ill patients may have skin rash, enlarged spleen, asthma, recurrent pulmonary infiltrates, abdominal pain, sleep & behavioral changes
Illness (VISCERAL LARVA MIGRANS) may persist for months. May die of respiratory failure, arrhythmia, brain damage
how do you diagnose Toxocara canis?
demonstrating larva in liver biopsy or at autopsy
Lab findings: increased eosinophils in peripheral blood, & increased IgE
Serodiagnosis using EIA is 75% sensitive & 90% specific
how do you treat Toxocara canis?
albendazole, mebendazole, diethylcarbamazine, or thiabendazole used
- no treatment if no symptoms
how do you prevent Toxocara canis?
Worming of pets begins @ 3 wks of age, repeat every 3 mos in 1st year, then 2x/ yr afterward.
where is Trichinella spp?
how do ppl get trichinosis?
Infection begins with ingestion of undercooked pork or bear meat containing encysted larvae;
how does Trichinella survive in you after you eat it?
encysted larvae liberated from meat by digestive enzymes, develop in
small intestine mucosa
what's the Trichinella life cycle?
Larvae released in intestines --> mature to adults, mate --> females produce live-born larvae -->penetrate intestinal wall --> enter blood stream --> all areas of body --> encapsulate in striated muscle
what are symptoms of Trichinella infec?
Few symptoms while intestinal phase:
Some diarrhea, abdominal discomfort
developed infection: periorbital edema, muscle pain & tenderness, headache, weakness, Myocarditis, CNS involvement, death may occur
myositis & vasculitis
how long can Trichinella larvae persist in body?
viable for years!
what are Trichinella symptoms dependent on?
tissue invaded, parasite load, general health of patient
how do you diagnose Trichinella?
Muscle biopsy (encysted larvae)
Trichinella tx?
Rx of adult worms in small intestine with mebendazole may halt production of new larvae
-no tx for larvae in muscle!
what are general char of trematodes/flukes?
Leaf-like and flat
Human (or another animal) is definitive host for all
Two intermediate hosts for most (schistosomes have one)
what's the normal trematode life cycle?
Eggs shed from human into fresh water (lake, pond, etc.) --> miracidia larvae hatch and infect mollusks (snails) --> cercaria larvae from snail enters water --> metacercaria invade 2nd intermediate host which is ingested by man
what's schistosoma alteration to normal trematode life cycle?
cercaria infect man through skin with no second intermediate host.
where can you find Schistosoma japonicum?
S. japonicum: S. E. Asia,
where can you find Schistosoma hematobium?
S. hematobium: Nile valley, Central Africa, Middle East,
where can you find Schistosoma mansoni?
S. mansoni: Africa, S. America, Caribbean, Phillipines
how do ppl get Schistosome infec?
Cercaria leave snail and penetrate human skin
where can you find Schistosomes in human body?
Large eggs are deposited in vessels of humans
-G.I tract: S. mansoni and S. japonicum
-Urinary bladder (bladder cancer) and lower G.I.tract: S. hematobium

“Swimmer’s Itch” (schistosomal dermatitis) - a diff Schistosoma sp.
is it a good thing to have Schistosomes in your body?
-Adults living in blood vessels of mesentary where they cause probs in liver and spleen
-In liver, eggs cause inflamm rxn --> extensive fibrosis
where can you find Schistosoma hematobium eggs?
how do you diagnose Schistosoma?
eggs! in urine- hematobium or feces- japonicum and mansoni
describe Schistosoma japonicum egg:
S. japonicum: (85 x 60 µ), rounded with small lateral spine
describe Schistosoma hematobium egg:
S. hematobium (150 x 55µ), oval with pointed terminal spine
describe Schistosoma mansoni egg:
S. mansoni: (150 x 50 µ), oval with long pointed lateral spine
what's the most common form of Schistosomiasis?
Schistosoma mansoni
GI – involves mesenteric vessels… causes probs in liver and spleen
how can you decrease infection w/ Schistosoma?
Proper fecal and urine sanitation
Avoid contact with water
Eradicate snails
Treat infected individuals
what is Fasciolopsis buski and where is it found?
Giant intestinal fluke (found only in china, Vietnam, Thailand, parts of Indonesia, Malaysia & India
what's Fasciola hepatic and where's it found?
Sheep liver fluke (found in Russia, Japan, Egypt, & many latin American countries; rare in US)
what is Opisthorchis (Clonorchis) sinensis -? where is it found?
Chinese liver fluke (found only in China, Japan, Korea, & Vietnam)
what's Paragonimus westermani -- ? where is it found?
Lung fluke (Occurs in Asia, Africa, India, & Latin America)
what are general char of tapeworms/cestodes?
Flatworms (members of Platyhelminthes)
Head (scolex) equipped with structures for attachment = suckers, some with hooklets (“armed”), & one with pair of lateral grooves only
Proglottids (individual segments) are diagnostic for some
Entire chain of proglottids is called a “strobila”
All are hermaphroditic (both male and female in each proglottid)
All tapeworms have larval stages; most require 1 or more intermediate hosts
6-hooked hexacanth embryos in embryonated eggs of all
what tapeworm doesn't require 1 or more intermediate hosts?
Hymenolepsis nana
what species of tapeworm doesn't have 6-hooked hexacanth embryo in embryonated egg?
D. latum which is operculated like a fluke egg
what's strobila?
chain of proglottids
what's the most common tapeworm in the US?
Hymenolepsis nana
*more common in kids
describe Hymenolepsis nana life cycle:
Simple life cycle; no intermediate host required. Eggs ingested
Embryo released
Invades mucosa & develops larva called cysticercoid
Larva enters lumen & attaches, develops to adult
Adult lays eggs
what kind of host is human in Hymenolepsis nana infection?
Human can be both definitive & intermediate host, thus autoinfection may occur.
what worm can you become autoinfected w/?
Hymenolepsis nana
how is Hymenolepsis nana transmitted?
Spread fecal- oral route, or by ingestion of infected arthropod
what are the hosts for H. nana infection?
-Rodent = reservoir host
-arthropod (beetle) can serve as intermediate
humans- definitive and intermediate host
how do you diagnose H. nana?
Thin shelled eggs in stool (30-45 µ) with hexacanth embryo, polar thickenings and filaments.
Adults: small (<40 mm), tiny armed scolex (20-30 µ), hooklets
how do you treat H. nana?
Praziquantel (or niclosamide)
where is Diphyllobothrium latum found in nature?
Found in temperate zones (even Scandinavia)
Found in U.S. – Northern midwest lakes
what's the only operculate tapeworm found in man?
Diphyllobothrium latum
what are the intermediates in Diphyllobothrium latum?
Two intermediates: copepod and freshwater fish
how is Diphyllobothrium latum transmitted?
Humans ingest raw/inadequately cooked fish
what are the symptoms of Diphyllobothrium latum?
Vague abdominal symptoms (diarrhea, etc), megaloblastic anemia (competition for B12)
how do you diagnose Diphyllobothrium latum?
-Based on ID of eggs or proglottids passed in stool
-Eggs (65 µ), operculate, aboperculate knob
-Proglottids are broader than long (often chain of proglottids passed)
-Scolex has bothria (slits) instead of suckers
what's the beef tapeworm?
T. saginata
what's the intermediate host for Taenia saginata?
Cattle are intermediate host
how common is Taenia saginata?
Worldwide but rare in U.S.
symptoms of Taenia saginata?
vague abdominal symptoms; passing of proglottids; gravid proglottids may crawl from anus
how do you diagnose T. saginata?
proglottids are longer than wide (15-20 uterine branches), scolex has no hooks
Eggs (40 µ), striated shell, hexacanth embryo (can’t differentiate from T. solium)
what's the definitive host for T. saginata?
how does Taenia saginata present itself in meat?
Bladder cyst - cysticercus - in beef muscle
how can you get Taenia saginata?
eating raw or undercooked beef
what's the Taenia saginata life cycle?
Scolex evaginates & attaches to small intestinal mucosa by suckers
Strobila develops (usually one/patient)
Proglottids become larger as they become filled with eggs
Do not lay eggs, but proglottids drop off, rupture & eggs in feces, or remain intact & passed in feces - crawl like inch worm
Cattle ingest eggs (e.g., cowboy defecates in pasture)
Ingested eggs invade & reach beef muscle & form cysticerci
what's a defining char of Taenia saginata?
Scolex of Taenia saginata has 4 suckers and no hooklets
what's the pork tapeworm?
Taenia solium
what are the hosts for Taenia solium?
intermediate- pig
definitive- human
how common is Taenia solium?
rare in US
what stage of Taenia solium is infective?
what are symptoms of Taenia solium?
-cystercerci in various organs (called Cysticercus cellulosae)
-Serious problem when larvae travel to brain or eye (cysticercosis) – headaches, seizures, psychiatric disturbances possible
what is special about a cysticercus?
invaginated scolex
how do you diagnose Taenia solium?
Eggs or proglottids found in stool
Eggs: can’t be differentiated from T. saginata (above)
Proglottids: similar to T. saginata except 7-13 uterine branches, scolex is armed (hooks)
what's a defining char of Taenia solium?
Scolex of Taenia solium has 4 suckers plus a double row of hooks.
what does black widow look like?
black w/ red hourglass
what kind of damage can black widow cause?
toxin mediated
describe damage of brown recluse:
forms severe localized lesion that ulcerates.. Systemic signs not as bad as black widow
what damage can bed bugs cause?
dermatitis lesions on skin
what's the official name of dog ticks?
Dermacenter variabilis
what are general char of Insecta?
3 body parts (head, thorax & abdomen), 3 pairs of legs, one pair of antennae, 1 or 2 pairs of wings (or no wings)
contrast lice and fleas:
Lice -Flattened dorsoventrally
Fleas- Flattened laterally
what's the body louse?
Pediculus humanus
where can you find body louse on person?
Nits (eggs) deposited clothing
how is body louse transmitted?
host to host
also diseases ex: typhus
what's head louse?
Pediculus capitis
where can you find head louse?
nits on hair - REMOVE!
*can see easier w/ wood's lamp or uv light
what's pubic louse?
Phthirus pubis
where can you find pubic louse?
Pubic hair or occasionally of axillae, eyebrows, beard
what are gen char of fleas?
3 pair of clawed legs – attached at thorax
Large hind legs for jumping
why aren't fleas our friends?
Transmit bacterial infections (plague, etc.), tapeworms (e.g., Hymenolepis diminuta)
what's the dog or cat flea called?
Ctenocephalides spp.
what's in the Arachnida class?
Ticks, mites, spiders and scorpions
what are gen char of ticks?
Chitinous shield
Mouth parts attached to fused body (globular body)
Head and antennae are absent
4 pair legs in adults (3 in larvae)
are ticks our friends?
NO! Transmit diseases (e.g., RMSF, Babesiosis,
-Anaplasma phagocytophilum (human granulocytic Ehrlichiosis), -Borrelia burgdorferi (Lyme disease)
what's the deer tick?
Ixodes scapularis
what's the lone star tick?
Amblyomma americanum
what's the lone star tick a vector for?
-Ehrlichia chaffeensis (monocytic Ehrlichiosis)
-Francisella tularensis (tularemia)
what's dog tick a vector for?
-Rickettsia rickettsia (Rocky Mountain Spotted Fever)
-Francisella tularensis
what's dog tick?
Dermacentor variabilis
is it a good idea to leave tick head inside you?
no! can get bac infecs
how do you take a tick out?
To remove (1) grasp tick’s mouthparts against skin using pointed tweezers; (2) pull back slowly & steadily. Be patient, the long, central mouthpart (“hypostome”) inserted in the skin is covered with sharp barbs, sometimes making removal difficult & time-consuming.
what are gen char of mites?
No chitinous shield
Short legs (larvae have 6, adults have 8)
how do mites infect you?
Burrows in skin and lays eggs
how are mites transmitted?
Host to host in crowded conditions, poor hygiene
what disease do mites cause? is it prevalent?
scabies- endemic in US
what's the itch mite?
Sarcoptes scabiei
what are symptoms of scabies?
intense itching particularly in the interdigital folds leads to excoriation of the skin secondary to scratching, which produces crusts & secondary bacterial infection