Angiostrongylus cantonensis Flashcards
Angiostrongylus cantonensis
Common Name:
Rat Lungworm
Angiostrongylus cantonensis
Was described by Chen in 1935 from domestic_____ in_______
rats
Canton, China
Angiostrongylus cantonensis
The worm normally lives in the lungs of______ but can cause___________ in man
rats
eosinophilic meningoencephalitis
Angiostrongylus cantonensis
Disease: (2)
• Angiostrongyliasis
• Eosinophilic meningoencephalitis
Angiostrongylus cantonensis
- 16 to 19 mm x 0.26 mm in diameter
Morphology
• Male:
- pale and filiform
- they have a well-developed__________
caudal bursa (kidney-shaped & single-lobed)
Angiostrongylus cantonensis
Morphology
• Female:
- pale and filiform
- 21 to 25 mm x 0.30-0.36 mm in diameter
- has_______ which are round spirally around the intestine (barber’s pole pattern)
- lays________ eggs/day
uterine tubules
15,000
Angiostrongylus cantonensis
Eggs
• Have delicate_____
• Measure 46-48 micra x 68 micra
•_________ when oviposited
hyaline shells
Unembryonated
Angiostrongylus cantonensis
Life Cycle
• Infective stage –
• Definitive host –
• Incidental host –
• Intermediate host –
3 rd stage larva
rats
humans
snails (Achantina fulica)
Angiostrongylus cantonensis
Diagnosis
• Relatively difficult
• Presumptive diagnosis is made by travel history and exposure
(3)
• CSF (10% eosinophilia in proportion to the WBC)
• CT Scan
• ELISA
Definitive Host
• Rats
Intermediate Host
Snails or slugs
• Achatina fulica (Giant African Snail), Hemiplecta sagittifera, Helicostyla macrostoma, Veginilus plebeius, Veronicella altae
Paratenic Host
• Crabs, freshwater shrimps
Accidental host
Humans
Epidemiology
• First human infection documented by Nomura and Lin in_____ in 1945
• Documented in at least___ countries
Taiwan
30
Biology: Adult
• 16-22mm by 0.25-0.35mm
• Posterior end: welldeveloped caudal bursa: kidney-shaped and single lobed
• Male
Biology of Adult
• 19-33mm by 0.28-0.50mm
• Uterine tubules wound spirally around the intestine observed through the____ cuticle
• _______pattern
• Blunt posterior end
• Lay 15,000 eggs per day
Female
transparent
Barber’s pole
Biology: Ova
• 46-48um by 68-74um
•______ with delicate_____ shells
•_____ when oviposited
Elongated ovoidal eggs; hyaline
Unembryonated
Biology: Larva
• Found in lungs of rodents
• Distinct small knob near the tip of the tail
Rhabditiform Larva
Biology: Larva
• Two well-developed chinitous rods below the buccal cavity
• Rods have expanded knob-like tips
• Filariform Larva
- Ingestion of snails, slugs
- Ingestion of paratenic hosts: crabs, freshwater shrimps
Humans
Pathogenesis and Clinical Manifestations
• BRAIN: primary site of infection
Eosinophilic meningoencephalitis
• Eosinophils on CSF
• Acute, severe, intermittent occipital or bitemporal headache
• Stiffness of neck, paresthesia, vomiting, fever, nausea, blurred vision, diplopia, myalgia, fatigue
• Confusion, incoherence, disorientation, memory lapses, coma
• Intraocular hemorrhage, blindness
Eosinophilic meningoencephalitis
Pathogenesis and Clinical Manifestations
eosinophilic inflammation of the mesenteric arterioles of the ileocecal region mimicking appendicitis
• Eosinophilic Enteritis
Pathogenesis and Clinical Manifestations
: due to dead worms
Inflammatory Reaction and Local tissue necrosis
Diagnosis
• Relatively difficult to diagnose since the primary site of infection is the____
brain
Presumptive diagnosis
• Travel and exposure history
• Clinical symptoms
• Medical history
• Laboratory findings
• Brain imaging
• Serological tests
Diagnosis
• Eosinophilia, elevated eosinophils in CSF similar with other CNS parasitism
Blood Tests
Diagnosis
• Cerebral edema, hydrocephalus, meningeal lesions
CT Scan
Treatment
No antihelminthic treatment
(2) may be effective
Mebendazole and albendazole
Treatment
______of the worm (eyes) Prednisone in severe cases of cranial nerve involvement
(2) for headache
Surgical removal
Analgesics and lumbar puncture
T or F
Resolve spontaneously: adult worm cannot survive for a long time inside human body
TRUE
Prevention and Control
• Awareness and education on proper eating habits and food preparation
• Discourage eating raw or poorly cooked ____or unwashed____
• Hand washing after gardening
• Use of molluscicides
• Metaldehyde or iron phosphate food bait pellets
• Copper barriers against snails and slugs
mollusks; vegetables
_____are ingested by definitive host.
Third-stage larvae
The ______ in rats are found in pulmonary arteries
Adult worms
Eggs hatch in the lungs, and ______ are passed in rodent feces
first-stage larvae
First-stage larvae shed from definitive host are ingested by______
gastropod intermediate host
Larvae reach the_____
stage after two molts in the intermediate host.
infective (third)
Larvae migrate to brain (occasionally eyes or lungs) in aberrant human host, and do not reach______
reproductive maturity
