HelminthologyHelminthology –– NematodesNematodes HookwormHookworm
TerryTerry LL DwelleDwelle MDMD MPHTMMPHTM
1 ClassificationClassification ofof NematodesNematodes
Subclass Order Superfamily Genus and Species Probable (suborder) prevalence in man Secernentea Strongylida Ankylostomatoidea Ankylostoma douodenale 716 million
Necator americanus
A caninum Thousands
A braziliense Thousands
A ceylanicum Rare Ternidens diminutus Thousands Oesophagostomum Rare apiostomum Syngamus laryngeus Rare
2 GeneralGeneral InformationInformation
►►TwoTwo majormajor species;species; AnkylostomaAnkylostoma duodenaleduodenale (old(old world),world), NecatorNecator AmericanusAmericanus (new(new world)world) ►►Others;Others; AA caninumcaninum,, AA braziliensebraziliense,, AA ceylanicumceylanicum ►►PrevalencePrevalence –– Africa,Africa, Asia,Asia, CentralCentral America,America, SouthSouth America,America, CaribbeanCaribbean Islands,Islands, SESE USUS
3 GeneralGeneral RecognitionRecognition FeaturesFeatures ► SizeSize Necator americanis – male 7-9 mm, female 10-18 mm Ankylostoma duodenale – male 8-11 mm, female 10-15 mm ► StructureStructure NA has a fused copulatory spicule vs AD AD totally dorsally flexed. NA is dorsally flexed but with a ventral flex near the head Two sets of reproductive organs Distinctive mouth parts Copulatory bursa ray patterns are distinctive ► EggsEggs 4 to 8 cells Thin shelled 60-75 um X 35-40 um 4 GeneralGeneral RecognitionRecognition FeaturesFeatures
► StructureStructure NA has a fused copulatory spicule vs AD AD totally dorsally flexed. NA is dorsally flexed but with a ventral flex near the head Two sets of reproductive organs Copulatory bursa ray patterns are distinctive for male worms
From Manson’s Tropical Disease, 20th Edition, Saunders, pp 1621 5 GeneralGeneral RecognitionRecognition FeaturesFeatures
From Manson’s Tropical Disease, 20th Edition, Saunders, pp 1622 6 GeneralGeneral RecognitionRecognition FeaturesFeatures
A Caninum
A Duodenale
From a Color Atlas of Tropical Medicine and Parasitology, 2nd edition, Yearbook Medical Publishers, pp 148-149 N Americanus A Ceylanicum 7 GeneralGeneral RecognitionRecognition FeaturesFeatures
From Manson’s Tropical Disease, 20th Edition, Saunders, pp 1621-1622 8 GeneralGeneral RecognitionRecognition FeaturesFeatures
From a Color Atlas of Tropical Medicine and Parasitology, 2nd edition, Yearbook Medical Publishers, pp 148-149 9 GeneralGeneral RecognitionRecognition FeaturesFeatures
10 LifeLife CycleCycle
►►DefinitiveDefinitive hosthost –– manman ►►StageStage leavingleaving thethe bodybody –– fertilefertile eggseggs ►►InfectiousInfectious stagestage forfor thethe definitivedefinitive hosthost –– L3L3 larvaelarvae
11 PrepatencyPrepatency andand IncubationIncubation PeriodPeriod
►►PrepatencyPrepatency –– 88--1212 weeksweeks ►►IncubationIncubation periodperiod –– 44--1212 weeksweeks
12 LifeLife CycleCycle
L3 Filariform Larvae Penetrates skin within a few minutes L1 rhabdiform Larvae Skin GI 24-48 hours Meat Breast Milk
Soil loose, sandy Blood
Rhabditis like esophagus
Eggs 5000/day NA, 20,000/day AD AD 5-7w, NA 4-6w Lungs 6 – 10 days
Small Intestine Largnx
Life span 5-10 years Esophagus
13 LifeLife CycleCycle
L3 Filariform Larvae Penetrates skin within a few minutes L1 rhabdiform Larvae Skin GI 24-48 hours Meat Breast Milk
Soil loose, sandy Blood
Rhabditis like esophagus
Eggs 5000/day NA, 20,000/day AD Lungs
6 – 10 days
Small Intestine Largnx
Life span 5-15 years Esophagus
14 15 SignsSigns andand SymptomsSymptoms
► GroundGround itchitch duedue toto vesiculationvesiculation andand pustulationpustulation atat thethe entryentry sitesite Exposed portions of the body usually the soles of the feet or hands ► AsthmaAsthma andand bronchitisbronchitis causedcaused byby migrationmigration ofof thethe larvaelarvae throughthrough thethe lungslungs 1-2 weeks associated with dry cough and wheezing ► EstablishedEstablished infectioninfection associatedassociated withwith hookwormhookworm diseasedisease
16 EstablishedEstablished InfectionInfection
•• LightLight infectioninfection ((<<100100 worms)worms) • Mild anemia • Fatique • Lassitude • Digestive disturbances • Eosinophilia
17 EstablishedEstablished InfectionInfection
• Heavy infection (>400 worms) – • Fatique • Lassitude • Eosinophilia • Epigastric apin • Perverted taste – pica, geophagy • Hematochezia / melena • Anemia • Edema associated with hypoalbuminemia • Heart failure • Hypothermia • Retinal hemorrhages • Irregular fever • Growth failure
18 WakanaWakana diseasedisease
►►AssociatedAssociated withwith oraloral infectioninfection withwith ADAD inin JapanJapan ►►NoNo larvaelarvae areare foundfound inin thethe lunglung ►►HasHas cough,cough, dyspneadyspnea,, eosinophiliaeosinophilia,, nauseanausea andand vomitingvomiting ►►SeenSeen oneone toto severalseveral daysdays afterafter ingestioningestion ofof larvaelarvae ►►EtiologyEtiology isis notnot knownknown
19 InfantileInfantile DiseaseDisease
►►MostlyMostly reportedreported fromfrom ChinaChina ►►MainlyMainly causedcaused byby AA DuodenaleDuodenale ►►TransmissionTransmission –– transtrans--mammary,mammary, layinglaying infantsinfants onon infectedinfected soil,soil, andand rarelyrarely transtrans-- placentalplacental ►►SignsSigns andand symptomssymptoms –– diarrhea,diarrhea, hematocheziahematochezia // melenamelena,, anorexia,anorexia, vomiting,vomiting, pallor,pallor, massivemassive hemorrhagehemorrhage ►►MortalityMortality –– 12%12%
20 21 DiagnosisDiagnosis
► EggsEggs inin thethe stoolstool Heavy infection – Direct stool smear with saline or potassium iodide saturated with iodine Light infection – Concentration techiques (Kato-Katz, Beaver direct smear, Stoll egg counting techique) Late prepatent period Charcot Leyden crystals and eosinophils may be seen in the feces similar to whipworm > 20 eggs / mg associated with anemia in NA vs > 5 eggs / mg with AD
22 Hookworm Hookworm
Capillaria PhilippinensisHookworm Egg
Trichostrongylus Strongyloides stercoralis larva Trichostrongylus Egg Trichuris trichuria Hookworm
23 TreatmentTreatment
DrugDrug AdultAdult PediatricPediatric
AlbendazoleAlbendazole 400400 mgmg onceonce 400400 mgmg onceonce MebendazoleMebendazole 100100 mgmg bidbid XX 33 100100 mgmg bidbid XX 33 daysdays oror 500500 mgmg daysdays oror 500500 mgmg onceonce onceonce PyrantelPyrantel 1111 mg/kgmg/kg (max(max 1111 mg/kgmg/kg (max(max pamoatepamoate 11 gm)gm) XX 33 daysdays 11 gm)gm) XX 33 daysdays
24 AdverseAdverse ReactionsReactions
Albendazole Occasional: diarrhea, abdominal pain Rare: leukopenia, alopecia, increased serum transaminase levels
Mebendazole Occasional: diarrhea, abdominal pain Rare: leukopenia, agranulocytosis, hypospermia
Pyrantel pamoate Occasional: GI distrubances, headache, dizziness, rash, fever
25 ControlControl MeasuresMeasures
►►SanitarySanitary disposaldisposal ofof fecesfeces ►►TreatmentTreatment ofof allall knownknown infectedinfected people.people. ScreeningScreening ofof highhigh riskrisk groupsgroups (agricultural(agricultural workersworkers andand children)children) maymay help.help. ►►WearingWearing shoesshoes inin endemicendemic areasareas ►►MassMass dede--wormingworming ofof schoolschool agedaged childrenchildren
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