Term
Ascaris lumbricoides
transmission
morphology
clinical
dx
misc |
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Definition
ingest eggs
unfertilized eggs aren't infective
larvae hatch, invade intestinal mucosa, and are carried via portal, then systemic circulation to the lungs, where they mature, are swallowed, and then re-enter intestine
Large intestinal nematodes (round worms)
Unsegmented bodies
20-30 cm
asymptomatic in many pts
ASCARIASIS
abdom cramping
dry cough and fever while in the lungs
malnutrition
bowel obstruction - abdom distension, fecal buildup, no pooping
cholecystitis
acute appendicitis
Fecal exam for eggs
sputum may reveal larvae
"bolus of parasites" |
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Term
Necator americanus
transmission
clinical
dx |
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Definition
(hookworm - nematode)
larvae penetrate through skin
adults live in SI - hooks, blood loss - anemia
1 cm long, un-segmented
Diarrhea, abdom pain, weight loss
*iron def anemia*
Itching at site of penetration + rash
fecal exam for eggs (hatch rapidly)
sputum may reveal larvae
eosinophilia: penetrate pulmonary alveoli, ascend to pharynx, are swallowed
-bronchitis, pneumonitis |
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Term
Strongyloides stercoralis
transmission
morphology
clinical
dx
misc |
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Definition
larvae penetrate through skin
*autoinfection* - larvae pass direclty through bowel or perianal skin to reinitiate development and migration to lungs --> hyperinfection (in immunocompromised pts)
adult females 2 mm long
V&D, anemia, weight loss
Occasional fatal case caused by massive autoinfection (in immunocompromised)
Itching and red blotches
bronchial pneumo
occas. bloody diarrhea
Fecal exam for LARVAE (no eggs!)
enterotest: swallow long nylon string and pull out, may show larvae
sputum - larvae
eosinophilia
Ab and Ag serum assay
Disseminated strongyloides - hyperinfxn where they migrate to other organs, like CNS |
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Term
Trichinella spiralis
transmission
morphology
clinical
dx |
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Definition
ingestion of encysted larvae, often found in raw pork
hatch in intestines - large numbers
cysts in skeletal muscle
fever, abdom pain, diarrhea
muscle aches, as larvae migrate to skeletal muscle
severe cases: larvae migrate to heart and brain
serology
muscle biopsy
i/c levels of muscle enzymes in blood
eosinophilia |
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Term
Trichuris trichiura
transmission
morphology
clinical
dx
misc |
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Definition
(whipworm)
ingest eggs
egg looks like football with polar bumps on each end
adults whip-shaped
diarrhea, abdom pain
fecal exam for eggs
NO eosinophilia
eggs must incubate in moist soil for 3-6 wks before they become infective |
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Term
Enterobius vermicularis (pinworm)
transmission
morphology
clinical
dx
misc |
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Definition
ingest eggs
1 cm long
severe perianal itching
scotch-tape test
exam of perineum at night
NO eosinophilia
female migrates to perianal area at night to lay eggs
most common helminth infxn
eggs are ovoid, but asymmetrically flat on one side |
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Term
Onchocerca volvulus
vector
disease |
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Definition
black fly, breeds in rivers and streams
River blindness - microfilariae migrate through the eye. Marked inflammatory response can occur upon their death, which can lead to blindness
disease is caused by allergic response to both microfillariae and dead adult worms |
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Term
Wucheria bancrofti and Brugia malayi
vector
disease |
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Definition
mosquito (transmits microfilariae)
Elephantiasis: following repeat infxns, fibrous tissue forms around the dead filariae that accumulates within the LN. This fibrous tissue plugs of the lymphatics, resulting in swelling of the legs and genitals. Thick, scaly skin covers the edematous lower extremities |
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Term
Dracunculus medinesis
transmission
morphology
clinical |
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Definition
larvae in African, ME and Indian freshwater copepods
larvae penetrate intestine, mature beneath the skin
Filariae: threadlike adult roundworms
allergic symtpoms occur during the release of microfilariae: N&V, hives, breathlessness |
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Term
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Definition
larvae of dog and cat tapeworms
creeping eruption: larvae of dog and cat hookworms penetrate the skin and migrate beneath the epidermis -> raised, red itchy rash moves with the advancing larvae |
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Term
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Definition
ingestion of eggs
larvae of dog roundworms, which can't mature in humans
Toxocariasis: migration of larvae through the body -> fever, diarrhea, wheezing, hepatitis, visual loss (from chorioretinitis) |
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Term
Schistosomes
transmission
morphology
clinical
dx
misc |
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Definition
blood flukes
penetrate through exposed skin
intermediate host = freshwater snail
-schistosomes mature, release larvae, larvae penetrate skin
Trematodes: eggs, mature larvae (called cercariae), adults
SCHISTOSOMIASIS
prutitic skin rash at site of penetration
Acute (Katayama fever): intense i tching, weeks later fever, hives, headache, weight loss, cough
Complications caused by immune rxn against eggs released by adults hanging out in the veins surrounding the intestine or bladder:
-liver: fibrosis of portal venous sytem -> portal HTN
-lung: fibrosis of pulmonary arterioles -> pulmonary HTN
Demonstration of eggs in stool or urine samples
Schistosoma haematobium: ID in urine
-Bladder infxn, granulomas, squamous cell carcinoma
S. japonicum and S. mansoni: ID in stool
lays eggs that adhere to epithelium, migrate through vessels into tissue
lodged -> granulomatous inflamm and egg sequestration -> portal HTN and fibrosis
eggs cause the inflammation and fibrosis in bladder |
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Term
Taenia solium
transmission
morphology
clinical
dx |
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Definition
Pork tapeworm
Ingest undercooked pork containing larvae stage
Ingestion of EGGS --> CYSTICERCOSIS
pig ingests eggs
human is asymptomatic or vague abdom pain - ingests undercooked pork with the LARVAE
If we eat the eggs, you get cysticercosis, human becomes "dead end" intermediate host
CESTODES
scolex: head with *hooks*
gravid proglottids: contains eggs and uterus has less than 15 pairs of lateral branches
Cysticercus: round, fluid-filled bladder with the larval form within
Adults can grow 2-8 meters
Intestinal infxn usually asymptomatic
Cysticercosis: eggs hatch in SI, larvae travel to muscle, CNS and/or the eye, where they eventually form calcified cysts that are inflammatory
-blindness
-neurologic manifestations
Fecal exam for eggs or gravid proglottids
CT scan or biopsy of brain or muscle may reveal *calcified cysticerci*
eosinophilia with cysticercosis
Cysticercosis occurs with ingestion of eggs (autoinfection)
Neurocysticercosis (cysts in brain) - solitary, encysted scolex |
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Term
Taenia saginata
transmission
morphology
clinical
dx |
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Definition
beef tapeworm
ingest undercooked beef containing larvae
Scolex: head with suckers but no hooks
Gravid proglottids
can grow to 10 m long
usually asymptomatic
occasionally develop abdom discomfort, weight loss, diarrhea
fecal exam for eggs or gravid proglottids |
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Term
Diphyllobothrium latum
transmission
morphology
clinical
dx |
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Definition
fish tapeworm
ingest larvae in raw freshwater fish
can grow to 45 m long
nonspecific abdom sx
*Vit B12 def -> macrocytic anemia*
ID eggs or gravid proglottids |
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Term
Echinococcus
transmission
clinical
dx |
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Definition
Hyatid disease, E. granulosis
Ingestion of fertilized eggs
*Hydatid cysts* form most often in liver and lung: enlarge over 1-20 yrs, producing sx by mass effect. Cysts can calcify
-liver: abdom pain, palpable liver mass, biliary obstruction, jaundice
-lung: cyst may rupture, causing cough or chest pain
-brain: intracranial pressure & epilepsy
Leakage of hydatid cyst fluid can cause a severe allergic rxn (anaphylaxis)
CT scan or ultrasound reveals cysts in liver or lung
Serology
EIA
Humans are intermediate host |
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