Strongyloides

Morning ReportDec 14th, 2009Nicole Cullen

What is Strongyloides?Parasitic infection with a predilection for the intestines2 most common and clinically relevant species are:Strongyloides stercoralisStrongyloides fuelleborniLimited to Africa and Papua New Guinea

EpidemiologyRelatively uncommon in the USBUT, endemic areas in the rural parts of the Southeastern states and the Appalachian mountain areaCertain pockets with prevalence 4%Usually found in tropical and subtropical countriesPrevalence up to 40% in areas of West Africa, the Caribbean, Southeast AsiaAffects >100 million worldwideNo sexual or racial disparities. All age groups.

How Do You Get It?Penetration of intact skin by filiariform larvae in the soil, or ingestion through contaminated food or waterLarvae enter the circulationLungs alveoli ascension up tracheobronchial tree swallowed molt in the small bowel and mature into adult femaleFemales enter the intestinal mucosa and produce several eggs daily through parthenogenesis (hatch during transit through the gut)

Clinical PresentationAcute infection:Lower extremity itching (mild erythematous maculopapular rash at the site of skin penetration)Cough, dyspnea, wheezingLow-grade feversEpigastric discomfort, n/v/d

Clinical PresentationChronic InfectionCan be completely asymptomaticAbdominal pain that can be very vague, crampy, burning Often worse after eatingIntermittent diarrheaCan alternate with constipationOccasional n/vWeight loss (if heavy infestation)Larva currens (racing larva a recurrent maculopapular or serpiginous rash)Usually begins perianally and extends up the buttocks, upper thighs, abdomenChronic urticaria

Larva Currens

Clinical PresentationSevere infectionCan be abrupt or insidious in onsetN/v/d, severe abdominal pain, distentionCough, hemoptysis, dyspnea, wheezing, cracklesStiff neck, headache, MS changes If CNS involvedFever/chillsHematemesis, hematocheziaRash (petechiae, purpura) over the trunk and proximal extremitiesCaused by dermal blood vessel disruption brought on by massive migration of larvae within the skinRisk factors for severe infectionImmunosuppressant meds (steroids, chemo, TNF modulators, tacro, etc all BUT cyclosporine)MalignancyMalabsorptive stateESRDDMAdvanced ageHIVHTLV1Etoh

Clinical PresentationCan replicate in the host for decades with minimal or no sxHigh morbidity and mortality when progresses to hyperinfection syndrome or disseminated strongyloidiasisUsually in immunocompromised hosts (pregnancy?)

Dangerous ComplicationsHyperinfection SyndromeAcceleration of the normal life cycle, causing excessive worm burdenAutoinfection (turn into infective filariform larva within the lumenSpread of larvae outside the usual migration pattern of GI tract and lungs Disseminated strongyloidiasisWidespread dissemination of larvae to extraintestinal organs CNS (meningitis), heart, urinary tract, bacteremia, etcCan be complicated by translocation of enteric bacteriaTravel on the larvae themselves or via intestinal ulcersMortality rate close to 80%Due to delayed diagnosis, immunocompromised state of the host at this point

Laboratory FindingsCBCWBC usually wnl for acute and chronic cases, can be elevated in severe casesEosinophilia common during acute infection, +/- in chronic infection (75%), usually absent in severe infection

Diagnostic TestingStool O&PMicroscopic ID of S. sterocoralis larvae is the definitive diagnosisOva usually not seen (only helminth to secrete larva in the feces)Stool wet mount (direct exam)In chronic infection, sensitivity only 30%, can increase to 75% if 3 consecutive stool examsCan enhance larvae recovery with more obscure methods (Baermann funnel, agar plate, Harada-Mori filter paper)

Wet Mount

Larva seen via direct examination of stool

SerologyELISAMost sensitive method (88-95%)May be lower in immunocompromised patientsCannot distinguish between past and present infectionsCan cross-react with other nematode infectionsIf results are positive, can move on to try and establish a microscopic dx

ImagingCXR patchy alveolar infiltrates, diffuse interstitial infiltrates, pleural effusionsAXR Loops of dilated small bowel, ileusBarium swallow stenosis, ulceration, bowel dilitationSmall bowel follow-through worms in the instestineCT abdomen/pelvis nonspecific thickening of the bowel wall

ProceduresEGD duodenitis, edematous mucosa, white villi, erythemaColonoscopy colitisDuodenal aspiration examine for larvaeSputum sample, bronchial washings, BAL show larvaeSputum cxNl respiratory flora organisms pushed to the outside in groups as a result of migrating larvaeCharacteristic pattern can be diagnostic of S.Stercoralis infectionIf CNS involved, LP gram stain, cell count/diff ( protein, glu, poly predominance), wet mount prep

HistologyLarvae typically found in proximal portion of small intestineEmbedded in lamina propriaCause edema, cellular infiltration, villous atrophy, ulcerationsIn-long standing infections, may see fibrosis

TreatmentAntihelminitic therapyIvermectinAlbendazoleThiabendazoleAbx directed toward enteric pathogens if bacteremia or meningitis (2-4wks)Minimize immunosuppression as possibleDirected supportive txTransfusions if GI bleed, antihistamines for itching, surgery if bowel perf, etcRepeat course of antihelminitic therapy if immunocompromised, as relapse common

Follow-UpRepeat stool exams or duodenal aspirations in 2-3 mos to document cureRepeat serologies 4-8 mos after therapy Ab titer should be low or undetectable 6-18 mos after successful txIf titer not falling, additional antihelminitic txPrecautions for travelers to endemic areas, but no prophylaxis or vaccine available

ReferencesArch EL, Schaefer JT and Dahiya A. Cutaneous manifestation of disseminated strongyloidiasis in a patient coinfected with HTLV-1. Dermatology Online Journal. 2008;14(12):6.Chadrasekar PH, Bharadwaj RA, Polenakovik H, Polenakovik S. Emedicine: Strongyloidiasis. April 3, 2009.Concha R, Harrington W and Rogers A. Intestinal Strongyloidiasis. Recognition, Management and Determinants of Outcome. Journal of Clinical Gastroengerology. 2005;39(3):203-211.Greiner K, Bettencourt J, and Semolic C. Strongyloidiasis: A Review and Update by Case Example. Clinical Laboratory Science. 2008;21(2):82-8.Siddiqui AA, Berk SL. Diagnosis of Strongyloides stercoralis infection. Clin Infect Dis. October 1, 2001;33:1040-7. Zeph, Bill. Strongyloides stercoralis Infection Can Be Fatal. American Family Physician. March 15, 2002.