HelminthologyHelminthology –– NematodesNematodes StrongyloidesStrongyloides
TerryTerry LL DwelleDwelle MDMD MPHTMMPHTM ClassificationClassification ofof NematodesNematodes
Subclass Order Superfamily Genus and Species Probable (suborder) prevalence in man Secernentea Rhabditida Rhabditoidea Strongyloides stercoralis 56 million
Stronglyloides myoptami Occasional
Strongyloides fuelloborni Millions
Strongyloides pyocyanis Occasional GeneralGeneral InformationInformation
► PrimarilyPrimarily aa diseasedisease ofof tropicaltropical andand subtropicalsubtropical areas,areas, highlyhighly prevalentprevalent inin Brazil,Brazil, Columbia,Columbia, andand SESE AsiaAsia ► ItIt isis notnot uncommonuncommon inin institutionalinstitutional settingssettings inin temperatetemperate climatesclimates ((egeg mentalmental hospitals,hospitals, prisons,prisons, childrenchildren’’ss homes)homes) ► SeriousSerious problemproblem inin thosethose onon immunosuppressiveimmunosuppressive therapytherapy ► HigherHigher prevalenceprevalence inin areasareas withwith aa highhigh waterwater tabletable GeneralGeneral RecognitionRecognition FeaturesFeatures
► Size;Size; parasiticparasitic femalefemale 2.72.7 mm,mm, freefree livingliving femalefemale 1.21.2 mm,mm, freefree livingliving malemale 0.90.9 mmmm ► EggsEggs –– 5050--5858 XX 3030--3434 umum ► TheThe RhabdiformRhabdiform larvaelarvae havehave aa shortershorter buccalbuccal canalcanal vsvs hookwormhookworm ► LarvaeLarvae havehave aa doubledouble laterallateral alaealae,, smallersmaller thanthan hookwormhookworm ► S.S. fuellobornifuelloborni –– freefree livingliving femalefemale hashas aa distinctdistinct postpost vulvarvulvar constrictionconstriction Manson’s Tropical Diseases, GC Cook, 12th Edition, Saunders, pp 1627 Buccal Space
Double Lateral Alae LifeLife CycleCycle
►►DefinitiveDefinitive hosthost SS stercoralisstercoralis -- man,man, dogs,dogs, primatesprimates SS myoptamimyoptami –– nutreanutrea SS fuellobornifuelloborni –– man,man, primatesprimates SS pyocyanispyocyanis –– man,man, raccoonraccoon ►►StageStage leavingleaving thethe bodybody –– RhabdiformRhabdiform larvaelarvae ►►InfectiousInfectious stagestage forfor thethe definitivedefinitive hosthost –– L3L3 filariformfilariform larvaelarvae LifeLife CycleCycle
Intestine Adults mate Penetrates the mucosa Eggs produce 2 molts – 2 weeks
Crypts of Lieberkuhn Trachea Life Cycle In bronchial mucosa L1 Rhabditoid Lungs larvae hatch L3 Filariform Larvae Colonic mucosa L3 Filariform Larvae Stool Skin L3 Filariform Larvae Perineal skin Soil L3 Filariform Larvae Warm and moist Soil 24-36 hours Internal Autoinfection L3 Filariform Larvae Free living External Autoinfection rhabditoid adults Soil – Direct Development Male and female – 3-5 days
Soil – Indirect Development Eggs produced LifeLife CycleCycle
Intestine Adults mate Penetrates the mucosa Eggs produce 2 molts – 2 weeks
Crypts of Lieberkuhn Trachea Life Cycle In bronchial mucosa L1 Rhabditoid Lungs larvae hatch L3 Filariform Larvae Colonic mucosa L3 Filariform Larvae Stool Skin L3 Filariform Larvae Perineal skin Soil L3 Filariform Larvae Warm and moist Soil 24-36 hours Internal Autoinfection L3 Filariform Larvae Free living External Autoinfection rhabditoid adults Soil – Direct Development Male and female – 3-5 days
Soil – Indirect Development Eggs produced LifeLife CycleCycle
Intestine Adults mate Penetrates the mucosa Eggs produce 2 molts – 2 weeks
Crypts of Lieberkuhn Trachea Life Cycle In bronchial mucosa L1 Rhabditoid Lungs larvae hatch L3 Filariform Larvae Colonic mucosa L3 Filariform Larvae Stool Skin L3 Filariform Larvae Perineal skin Soil L3 Filariform Larvae Warm and moist Soil 24-36 hours Internal Autoinfection L3 Filariform Larvae Free living External Autoinfection rhabditoid adults Soil – Direct Development Male and female – 3-5 days
Soil – Indirect Development Eggs produced LifeLife CycleCycle
Intestine Adults mate Penetrates the mucosa Eggs produce 2 molts – 2 weeks
Crypts of Lieberkuhn Trachea Life Cycle In bronchial mucosa L1 Rhabditoid Lungs larvae hatch L3 Filariform Larvae Colonic mucosa L3 Filariform Larvae Stool Skin L3 Filariform Larvae Perineal skin Soil L3 Filariform Larvae Warm and moist Soil 24-36 hours Internal Autoinfection L3 Filariform Larvae Free living External Autoinfection rhabditoid adults Soil – Direct Development Male and female – 3-5 days
Soil – Indirect Development Eggs produced LifeLife CycleCycle
Intestine Adults mate Penetrates the mucosa Eggs produce 2 molts – 2 weeks
Crypts of Lieberkuhn Trachea Life Cycle In bronchial mucosa L1 Rhabditoid Lungs larvae hatch L3 Filariform Larvae Colonic mucosa L3 Filariform Larvae Stool Skin L3 Filariform Larvae Perineal skin Soil L3 Filariform Larvae Warm and moist Soil 24-36 hours Internal Autoinfection L3 Filariform Larvae Free living External Autoinfection rhabditoid adults Soil – Direct Development Male and female – 3-5 days
Soil – Indirect Development Eggs produced Strongyloides
Forked Tail Alveolar lining Eggs Stronglyloides Adult Infiltrate
Larva LifeLife CycleCycle
Intestine Adults mate Penetrates the mucosa Eggs produce 2 molts – 2 weeks
Crypts of Lieberkuhn Trachea Life Cycle In bronchial mucosa L1 Rhabditoid Lungs larvae hatch L3 Filariform Larvae Colonic mucosa L3 Filariform Larvae Stool Skin L3 Filariform Larvae Perineal skin Soil L3 Filariform Larvae Warm and moist Soil 24-36 hours Internal Autoinfection L3 Filariform Larvae Free living External Autoinfection rhabditoid adults Soil – Direct Development Male and female – 3-5 days
Soil – Indirect Development Eggs produced LifeLife CycleCycle
Intestine Adults mate Penetrates the mucosa Eggs produce 2 molts – 2 weeks
Crypts of Lieberkuhn Trachea Life Cycle In bronchial mucosa L1 Rhabditoid Lungs larvae hatch L3 Filariform Larvae Colonic mucosa L3 Filariform Larvae Stool Skin L3 Filariform Larvae Perineal skin Soil L3 Filariform Larvae Warm and moist Soil 24-36 hours Internal Autoinfection L3 Filariform Larvae Free living External Autoinfection rhabditoid adults Soil – Direct Development Male and female – 3-5 days
Soil – Indirect Development Eggs produced LifeLife CycleCycle
► All filariform larvae can swim ► Generally strongyloides has a lower prevalence than hookworm
► Strongyloides L3 filariform larvae are not infectious by the oral route except for S fuellobourni
► Adults are more commonly affected than children ► The infection usually occurs through exposure to infected soil
► Transmission by breast milk has been demonstrated in animals and is likely in man
► Prepatent period – 4 weeks ► Patent period - 30 + years
ClinicalClinical PresentationPresentation
►►HalfHalf ofof thethe casescases areare mildlymildly symptomaticsymptomatic oror asymptomaticasymptomatic RecurrentRecurrent rashrash –– LarvaeLarvae currenscurrens –– startsstarts fromfrom thethe perianalperianal areaarea andand movesmoves rapidlyrapidly (10(10 cmcm // day)day) toto buttocks,buttocks, thighsthighs andand trunktrunk UrticariaUrticaria GastrointestinalGastrointestinal complaintscomplaints –– mimicsmimics pepticpeptic ulcer,ulcer, RUQRUQ painpain ChronicChronic pulmonarypulmonary symptomssymptoms EosinophiliaEosinophilia
ClinicalClinical PresentationPresentation
►►SevereSevere infectioninfection –– immunocompromisedimmunocompromised MayMay causecause fatalfatal hyperinfectionhyperinfection GastrointestinalGastrointestinal –– diarrhea,diarrhea, constipation,constipation, abdominalabdominal pain,pain, nauseanausea andand vomiting,vomiting, malabsorptionmalabsorption (fat,(fat, B12,B12, proteinprotein losinglosing enteropathyenteropathy)) HypereosinophiliaHypereosinophilia resemblingresembling tropicaltropical pulmonarypulmonary eosinophiliaeosinophilia (TPE)(TPE) LeukocytosisLeukocytosis Larvae DifferentialDifferential DiagnosisDiagnosis
►►AscarisAscaris ►►HookwormHookworm ►►SchistosomiasisSchistosomiasis ►►TropicalTropical PulmonaryPulmonary EosinophiliaEosinophilia ►►CutaneousCutaneous LarvaLarva MigransMigrans (CLM)(CLM) ►►VisceraViscera LarvaLarva MigransMigrans (VLM)(VLM) DiagnosisDiagnosis
► StoolStool examinationexamination ► DuodenalDuodenal fluidfluid Enterotest (HDC Corporation, San Jose, CA) Duodenal aspirate via endoscope ► SputumSputum inin disseminateddisseminated infectioninfection ► SerodiagnosisSerodiagnosis EIA 85% sensitive Cross reaction with filaria infections ► EosinophiliaEosinophilia -- >> 500500 // uLuL Hookworm
Strongyloides Rhabdiform Larvae
Trichostrongylus TreatmentTreatment
Drug Adult dosage Pediatric dosage
Ivermectin (Drug of 200 ug/kg/d X 1-2 days 200 ug/kg/d X 1-2 days choice) Albendazole (IND drug) 400 mg bid X 7 days 400 mg bid X 7 days
Thiabendazole (Alternate) 50 mg/kg/day divided into 50 mg/kg/day divided into q12h doses (maximum 3 q12h doses (maximum 3 gms/day) X 2 days gms/day) X 2 days Consider 5 or more days Consider 5 or more days for disseminated disease for disseminated disease
Medical Letter, August, 2004, Drugs for Parasitic Infections, Nelson’s Pocket Book of Pediatric Antimicrobial Therapy, 15th Edition, Lippincott Williams, Wilkins, 2202-2003 AdverseAdverse ReactionsReactions DrugDrug FrequentFrequent OccasionalOccasional RareRare
Ivermectin Fever, pruritus, tender hypotension lymphnodes, headache, joint and bone pain
Albendazole Diarrhea, abdominal pain Leukopenia, alopecia, increased serum transaminase levels
Thiabendazole Nausea, vomiting, Leudopenia, crystalluria, Shock, tinnitus, vertigo rash, hallucinations, intrahepatic olfactory disturbance, cholestasis, erythema multiforme, convulsions, Steven’s Johnson syndrome angioneurotic edema ControlControl MeasuresMeasures
► SanitarySanitary disposaldisposal ofof humanhuman wastewaste ► EducationEducation aboutabout thethe riskrisk ofof infectioninfection throughthrough barebare skinskin inin endemicendemic areasareas ► ImmunodeficientImmunodeficient patientpatient endemicendemic areaarea considerconsider examinationexamination ofof thethe stool,stool, duodenalduodenal fluidfluid andand sputumsputum ► AA patientpatient requiringrequiring immunosuppressiveimmunosuppressive therapytherapy ((egeg cancercancer chemotherapy)chemotherapy) fromfrom anan endemicendemic areaarea considerconsider examinationexamination ofof thethe stool,stool, duodenalduodenal fluidfluid andand sputumsputum beforebefore treatmenttreatment withwith immunosuppressivesimmunosuppressives