Helminthology Helminthology – – Nematodes Nematodes Angiostrongylus Angiostrongylus Terry L Terry L Dwelle Dwelle MD MPHTM MD MPHTM
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HelminthologyHelminthology –– Nematodes Nematodes AngiostrongylusAngiostrongylus
Terry L Terry L DwelleDwelle MD MPHTMMD MPHTM
Classification of NematodesClassification of Nematodes
SubclassSubclass Order Order (suborder)(suborder)
SuperfamilySuperfamily Genus and SpeciesGenus and Species Probable Probable prevalence in prevalence in manman
SecernenteaSecernentea StrongylidaStrongylida MetastrongyloideaMetastrongyloidea AngiostrongylusAngiostrongylus costraricensiscostraricensis
ThousandsThousands
AngiostrongylusAngiostrongylus cantonensiscantonensis ThousandsThousands
General InformationGeneral Information
►►Geographic distributionGeographic distributionA A costaricensiscostaricensis –– Costa Rica, Honduras, El Costa Rica, Honduras, El Salvador, Mexico, Columbia, Brazil Salvador, Mexico, Columbia, Brazil A A cantonensiscantonensis –– China, Australia, Malaysia, China, Australia, Malaysia, Taiwan, New Caledonia, Fiji, Guam, Taiwan, New Caledonia, Fiji, Guam, PonapePonape, , TrukTruk, Tahiti, Hawaii, Japan, N Sumatra, C Java, , Tahiti, Hawaii, Japan, N Sumatra, C Java, IndiaIndia
General Recognition FeaturesGeneral Recognition Features
►►SizeSizeA A costaricensiscostaricensis –– male 22 mm, female 42 mmmale 22 mm, female 42 mmA A cantonensiscantonensis –– 1717--25 mm25 mm
Adult Angiostrongylus cantonensis worms
1st stage rhabdiform larvae in rat feces
A Colour Atlas of Tropical Medicine and Parasitology, 2nd edition, Yearbook Medical Publishers
Life Cycle Life Cycle –– A A costaricensiscostaricensis
►►DefinativeDefinative host host –– cotton rat (cotton rat (SigmodonSigmodon HispidisHispidis), man), man
►►Where the adults live in the bodyWhere the adults live in the body-- appendicealappendiceal mesenteric arteriesmesenteric arteries
►►Stage leaving the rat Stage leaving the rat –– L1 L1 rhabdiformrhabdiform larvaelarvae►►Intermediate host Intermediate host –– slugsslugs►►Infectious stage for the host Infectious stage for the host –– L3 L3 filariformfilariform
larvae via ingestionlarvae via ingestion
L3 filariform infectious larvae in a snail host Achalina fulica
A Colour Atlas of Tropical Medicine and Parasitology, 2nd edition, Yearbook Medical Publishers
Life Cycle Life Cycle –– A A costaricensiscostaricensisL3 filariform larvae16-19days
Mesenteric artery of the appendixCotton Rat
Eggs18 days
Intestinal wall
L1 rhadiform larvae24 daysGI lumen
Feces
SlugIntermediate host
Mesenteric artery of the appendixMan
Larvae eaten
No patency
Life Cycle Life Cycle –– A A costaricensiscostaricensisL3 filariform larvae16-19days
Mesenteric artery of the appendixCotton Rat
Eggs18 days
Intestinal wall
L1 rhadiform larvae24 daysGI lumen
Feces
SlugIntermediate host
Mesenteric artery of the appendixMan
Larvae eaten
No patency
Life Cycle Life Cycle –– A A costaricensiscostaricensisL3 filariform larvae16-19days
Mesenteric artery of the appendixCotton Rat
Eggs18 days
Intestinal wall
L1 rhadiform larvae24 daysGI lumen
Feces
SlugIntermediate host
Mesenteric artery of the appendixMan
Larvae eaten
No patency
Life Cycle Life Cycle –– A A costaricensiscostaricensisL3 filariform larvae16-19days
Mesenteric artery of the appendixCotton Rat
Eggs18 days
Intestinal wall
L1 rhadiform larvae24 daysGI lumen
Feces
SlugIntermediate host
Mesenteric artery of the appendixMan
Larvae eaten
No patency
Life Cycle Life Cycle –– A A costaricensiscostaricensisL3 filariform larvae16-19days
Mesenteric artery of the appendixCotton Rat
Eggs18 days
Intestinal wall
L1 rhadiform larvae24 daysGI lumen
Feces
SlugIntermediate host
Mesenteric artery of the appendixMan
Larvae eaten
No patency
Life Cycle Life Cycle –– A A costaricensiscostaricensisL3 filariform larvae16-19days
Mesenteric artery of the appendixCotton Rat
Eggs18 days
Intestinal wall
L1 rhadiform larvae24 daysGI lumen
Feces
SlugIntermediate host
Mesenteric artery of the appendixMan
Larvae eaten
No patency
Life Cycle Life Cycle –– A A costaricensiscostaricensisL3 filariform larvae16-19days
Mesenteric artery of the appendixCotton Rat
Eggs18 days
Intestinal wall
L1 rhadiform larvae24 daysGI lumen
Feces
SlugIntermediate host
Mesenteric artery of the appendixMan
Larvae eaten
No patency
Life Cycle Life Cycle –– A A costaricensiscostaricensisL3 filariform larvae16-19days
Mesenteric artery of the appendixCotton Rat
Eggs18 days
Intestinal wall
L1 rhadiform larvae24 daysGI lumen
Feces
SlugIntermediate host
Mesenteric artery of the appendixMan
Larvae eaten
No patency
Life Cycle A Life Cycle A costaricensiscostaricensis
►►PrepatentPrepatent period period –– none none ►►Patent period Patent period –– nonenone►►Factors influencing transmission Factors influencing transmission –– primarily primarily
an infection of children 6an infection of children 6--13 years old13 years old
Disease CharacteristicsDisease Characteristics
►►Acute appendicitisAcute appendicitis
DiagnosisDiagnosis
►►Clinical suspicionClinical suspicion►►HistologyHistology
TreatmentTreatment
►►Surgery is curative (appendectomy)Surgery is curative (appendectomy)►►May be a self limited course with complete May be a self limited course with complete
recoveryrecovery►►May respond to analgesics and May respond to analgesics and
corticosteroidscorticosteroids►►AntiAnti--helminthhelminth therapy may worsen the therapy may worsen the
symptomssymptoms
Life Cycle Life Cycle –– A A cantonensiscantonensis
►►Definitive host Definitive host –– rat (rat (rattusrattus), man), man►►Where the adults live in the body Where the adults live in the body –– pulpul
arteries of rats, brain or eye of humansarteries of rats, brain or eye of humans►►Stage leaving the rat Stage leaving the rat –– L1 L1 rhabdiformrhabdiform larvaelarvae►►Intermediate host Intermediate host –– land and aquatic snails land and aquatic snails
and slugsand slugs►►Infectious stage for the host Infectious stage for the host –– L3 L3 filariformfilariform
larvae via ingestionlarvae via ingestion
Achalina fulica Cipangopaludina chinensis
Bradybaena similaris
A Colour Atlas of Tropical Medicine and Parasitology, 2nd edition, Yearbook Medical Publishers
Life Cycle Life Cycle –– A A cantonensiscantonensis
L3 filariform larvaeCNSRat
Eggs
Respiratory tree
L1 rhadiform larvae
Gastro intestinal system
Feces
Snail or SlugIntermediate host
CNS or EyeMan
Larvae eaten
No patency
Lung ParenchymaCapillary bed
Ingestion or penetration of the foot pad
4 weeksL4 or early L5 larvae
Life Cycle Life Cycle –– A A cantonensiscantonensis
L3 filariform larvaeCNSRat
Eggs
Respiratory tree
L1 rhadiform larvae
Gastro intestinal system
Feces
Snail or SlugIntermediate host
CNS or EyeMan
Larvae eaten
No patency
Lung ParenchymaCapillary bed
Ingestion or penetration of the foot pad
4 weeksL4 or early L5 larvae
Life Cycle Life Cycle –– A A cantonensiscantonensis
L3 filariform larvaeCNSRat
Eggs
Respiratory tree
L1 rhadiform larvae
Gastro intestinal system
Feces
Snail or SlugIntermediate host
CNS or EyeMan
Larvae eaten
No patency
Lung ParenchymaCapillary bed
Ingestion or penetration of the foot pad
4 weeksL4 or early L5 larvae
Life Cycle Life Cycle –– A A cantonensiscantonensis
L3 filariform larvaeCNSRat
Eggs
Respiratory tree
L1 rhadiform larvae
Gastro intestinal system
Feces
Snail or SlugIntermediate host
CNS or EyeMan
Larvae eaten
No patency
Lung ParenchymaCapillary bed
Ingestion or penetration of the foot pad
4 weeksL4 or early L5 larvae
Life Cycle Life Cycle –– A A cantonensiscantonensis
L3 filariform larvaeCNSRat
Eggs
Respiratory tree
L1 rhadiform larvae
Gastro intestinal system
Feces
Snail or SlugIntermediate host
CNS or EyeMan
Larvae eaten
No patency
Lung ParenchymaCapillary bed
Ingestion or penetration of the foot pad
4 weeksL4 or early L5 larvae
Life Cycle Life Cycle –– A A cantonensiscantonensis
L3 filariform larvaeCNSRat
Eggs
Respiratory tree
L1 rhadiform larvae
Gastro intestinal system
Feces
Snail or SlugIntermediate host
CNS or EyeMan
Larvae eaten
No patency
Lung ParenchymaCapillary bed
Ingestion or penetration of the foot pad
4 weeksL4 or early L5 larvae
Life Cycle Life Cycle –– A A cantonensiscantonensis
L3 filariform larvaeCNSRat
Eggs
Respiratory tree
L1 rhadiform larvae
Gastro intestinal system
Feces
Snail or SlugIntermediate host
CNS or EyeMan
Larvae eaten
No patency
Lung ParenchymaCapillary bed
Ingestion or penetration of the foot pad
4 weeksL4 or early L5 larvae
Life Cycle Life Cycle –– A A cantonensiscantonensis
L3 filariform larvaeCNSRat
Eggs
Respiratory tree
L1 rhadiform larvae
Gastro intestinal system
Feces
Snail or SlugIntermediate host
CNS or EyeMan
Larvae eaten
No patency
Lung ParenchymaCapillary bed
Ingestion or penetration of the foot pad
4 weeksL4 or early L5 larvae
Life Cycle Life Cycle –– A A cantonensiscantonensis
L3 filariform larvaeCNSRat
Eggs
Respiratory tree
L1 rhadiform larvae
Gastro intestinal system
Feces
Snail or SlugIntermediate host
CNS or EyeMan
Larvae eaten
No patency
Lung ParenchymaCapillary bed
Ingestion or penetration of the foot pad
4 weeksL4 or early L5 larvae
Prawns role??
Angiostrongylus cantonensis
Angiostrongylus cantonensis larvae
Subarachnoid hemorrhage
Larvae
DiagnosisDiagnosis
►►Clinical suspicionClinical suspicion►►HistologyHistology
TreatmentTreatment
►►May be a self limited course with complete May be a self limited course with complete recoveryrecovery
►►May respond to analgesics and May respond to analgesics and corticosteroidscorticosteroids
►►AntihelminthAntihelminth therapy may worsen the therapy may worsen the symptomssymptoms
Control MeasuresControl Measures
►►Avoid the eating of undercooked fresh water Avoid the eating of undercooked fresh water prawns, snails planarians, and slugs in prawns, snails planarians, and slugs in endemic areasendemic areas
►►Rodent, snail, slug and planarian control in Rodent, snail, slug and planarian control in endemic areasendemic areas
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