Helminthology – – Nematodes Nematodes Helminthology Angiostrongylus Angiostrongylus Terry L Dwelle Dwelle MD MPHTM MD MPHTM Terry L
Classification of Nematodes Classification of Nematodes Subclass Subclass Order Order Superfamily Superfamily Genus and Species Genus and Species Probable Probable (suborder) (suborder) prevalence in prevalence in man man Secernentea Secernentea Strongylida Strongylida Metastrongyloidea Metastrongyloidea Angiostrongylus Angiostrongylus Thousands Thousands costraricensis costraricensis Angiostrongylus cantonensis cantonensis Thousands Angiostrongylus Thousands
General Information General Information ► Geographic distribution ► Geographic distribution � A � A costaricensis costaricensis – – Costa Rica, Honduras, El Costa Rica, Honduras, El Salvador, Mexico, Columbia, Brazil Salvador, Mexico, Columbia, Brazil � A � A cantonensis cantonensis – – China, Australia, Malaysia, China, Australia, Malaysia, Taiwan, New Caledonia, Fiji, Guam, Ponape Ponape, , Taiwan, New Caledonia, Fiji, Guam, Truk, Tahiti, Hawaii, Japan, N Sumatra, C Java, , Tahiti, Hawaii, Japan, N Sumatra, C Java, Truk India India
General Recognition Features General Recognition Features ► Size ► Size � A � A costaricensis costaricensis – – male 22 mm, female 42 mm male 22 mm, female 42 mm � A � A cantonensis cantonensis – – 17 17- -25 mm 25 mm
1 st stage rhabdiform larvae in rat feces Adult Angiostrongylus cantonensis worms A Colour Atlas of Tropical Medicine and Parasitology, 2nd edition, Yearbook Medical Publishers
Life Cycle – – A A costaricensis costaricensis Life Cycle ► Definative ► Definative host host – – cotton rat ( cotton rat (Sigmodon Sigmodon Hispidis), man ), man Hispidis ► Where the adults live in the body ► Where the adults live in the body- - appendiceal mesenteric arteries mesenteric arteries appendiceal ► Stage leaving the rat ► Stage leaving the rat – – L1 L1 rhabdiform rhabdiform larvae larvae ► Intermediate host ► Intermediate host – – slugs slugs ► Infectious stage for the host ► Infectious stage for the host – – L3 L3 filariform filariform larvae via ingestion larvae via ingestion
A Colour Atlas of Tropical Medicine and Parasitology, 2nd edition, Yearbook Medical Publishers L3 filariform infectious larvae in a snail host Achalina fulica
Life Cycle – – A A costaricensis costaricensis Life Cycle L3 filariform larvae Mesenteric artery 16-19days of the appendix Larvae eaten Cotton Rat Eggs Slug Mesenteric artery 18 days Intermediate host of the appendix Man Intestinal wall Feces No patency L1 rhadiform larvae GI lumen 24 days
Life Cycle – – A A costaricensis costaricensis Life Cycle L3 filariform larvae Mesenteric artery 16-19days of the appendix Larvae eaten Cotton Rat Eggs Slug Mesenteric artery 18 days Intermediate host of the appendix Man Intestinal wall Feces No patency L1 rhadiform larvae GI lumen 24 days
Life Cycle – – A A costaricensis costaricensis Life Cycle L3 filariform larvae Mesenteric artery 16-19days of the appendix Larvae eaten Cotton Rat Eggs Slug Mesenteric artery 18 days Intermediate host of the appendix Man Intestinal wall Feces No patency L1 rhadiform larvae GI lumen 24 days
Life Cycle – – A A costaricensis costaricensis Life Cycle L3 filariform larvae Mesenteric artery 16-19days of the appendix Larvae eaten Cotton Rat Eggs Slug Mesenteric artery 18 days Intermediate host of the appendix Man Intestinal wall Feces No patency L1 rhadiform larvae GI lumen 24 days
Life Cycle – – A A costaricensis costaricensis Life Cycle L3 filariform larvae Mesenteric artery 16-19days of the appendix Larvae eaten Cotton Rat Eggs Slug Mesenteric artery 18 days Intermediate host of the appendix Man Intestinal wall Feces No patency L1 rhadiform larvae GI lumen 24 days
Life Cycle – – A A costaricensis costaricensis Life Cycle L3 filariform larvae Mesenteric artery 16-19days of the appendix Larvae eaten Cotton Rat Eggs Slug Mesenteric artery 18 days Intermediate host of the appendix Man Intestinal wall Feces No patency L1 rhadiform larvae GI lumen 24 days
Life Cycle – – A A costaricensis costaricensis Life Cycle L3 filariform larvae Mesenteric artery 16-19days of the appendix Larvae eaten Cotton Rat Eggs Slug Mesenteric artery 18 days Intermediate host of the appendix Man Intestinal wall Feces No patency L1 rhadiform larvae GI lumen 24 days
Life Cycle – – A A costaricensis costaricensis Life Cycle L3 filariform larvae Mesenteric artery 16-19days of the appendix Larvae eaten Cotton Rat Eggs Slug Mesenteric artery 18 days Intermediate host of the appendix Man Intestinal wall Feces No patency L1 rhadiform larvae GI lumen 24 days
Life Cycle A costaricensis costaricensis Life Cycle A ► Prepatent ► Prepatent period period – – none none ► Patent period ► Patent period – – none none ► Factors influencing transmission ► Factors influencing transmission – – primarily primarily an infection of children 6- -13 years old 13 years old an infection of children 6
Disease Characteristics Disease Characteristics ► Acute appendicitis ► Acute appendicitis
Diagnosis Diagnosis ► Clinical suspicion ► Clinical suspicion ► Histology ► Histology
Treatment Treatment ► Surgery is curative (appendectomy) ► Surgery is curative (appendectomy) ► May be a self limited course with complete ► May be a self limited course with complete recovery recovery ► May respond to analgesics and ► May respond to analgesics and corticosteroids corticosteroids ► Anti ► Anti- -helminth helminth therapy may worsen the therapy may worsen the symptoms symptoms
Life Cycle – – A A cantonensis cantonensis Life Cycle ► Definitive host ► Definitive host – – rat ( rat (rattus rattus), man ), man ► Where the adults live in the body ► Where the adults live in the body – – pul pul arteries of rats, brain or eye of humans arteries of rats, brain or eye of humans ► Stage leaving the rat ► Stage leaving the rat – – L1 L1 rhabdiform rhabdiform larvae larvae ► Intermediate host ► Intermediate host – – land and aquatic snails land and aquatic snails and slugs and slugs ► Infectious stage for the host ► Infectious stage for the host – – L3 L3 filariform filariform larvae via ingestion larvae via ingestion
Achalina fulica Cipangopaludina chinensis A Colour Atlas of Tropical Medicine and Parasitology, 2 nd edition, Yearbook Medical Bradybaena similaris Publishers
Life Cycle – – A A cantonensis cantonensis Life Cycle CNS L3 filariform larvae Lung Parenchyma Rat Capillary bed 4 weeks Larvae eaten L4 or early L5 larvae Snail or Slug CNS or Eye Eggs Intermediate host Man Ingestion or penetration of the foot pad L1 rhadiform larvae Feces No patency Respiratory tree Gastro intestinal system
Life Cycle – – A A cantonensis cantonensis Life Cycle CNS L3 filariform larvae Lung Parenchyma Rat Capillary bed 4 weeks Larvae eaten L4 or early L5 larvae Snail or Slug CNS or Eye Eggs Intermediate host Man Ingestion or penetration of the foot pad L1 rhadiform larvae Feces No patency Respiratory tree Gastro intestinal system
Life Cycle – – A A cantonensis cantonensis Life Cycle CNS L3 filariform larvae Lung Parenchyma Rat Capillary bed 4 weeks Larvae eaten L4 or early L5 larvae Snail or Slug CNS or Eye Eggs Intermediate host Man Ingestion or penetration of the foot pad L1 rhadiform larvae Feces No patency Respiratory tree Gastro intestinal system
Life Cycle – – A A cantonensis cantonensis Life Cycle CNS L3 filariform larvae Lung Parenchyma Rat Capillary bed 4 weeks Larvae eaten L4 or early L5 larvae Snail or Slug CNS or Eye Eggs Intermediate host Man Ingestion or penetration of the foot pad L1 rhadiform larvae Feces No patency Respiratory tree Gastro intestinal system
Life Cycle – – A A cantonensis cantonensis Life Cycle CNS L3 filariform larvae Lung Parenchyma Rat Capillary bed 4 weeks Larvae eaten L4 or early L5 larvae Snail or Slug CNS or Eye Eggs Intermediate host Man Ingestion or penetration of the foot pad L1 rhadiform larvae Feces No patency Respiratory tree Gastro intestinal system
Life Cycle – – A A cantonensis cantonensis Life Cycle CNS L3 filariform larvae Lung Parenchyma Rat Capillary bed 4 weeks Larvae eaten L4 or early L5 larvae Snail or Slug CNS or Eye Eggs Intermediate host Man Ingestion or penetration of the foot pad L1 rhadiform larvae Feces No patency Respiratory tree Gastro intestinal system
Life Cycle – – A A cantonensis cantonensis Life Cycle CNS L3 filariform larvae Lung Parenchyma Rat Capillary bed 4 weeks Larvae eaten L4 or early L5 larvae Snail or Slug CNS or Eye Eggs Intermediate host Man Ingestion or penetration of the foot pad L1 rhadiform larvae Feces No patency Respiratory tree Gastro intestinal system
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