escmid online lecture library lumc - parasitology© by

Department of ParasitologyLeiden University Medical Centre

Strongyloides

Lisette van Lieshout

[email protected]

Department of ParasitologyLUMC, The Netherlands

LUMC - P

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ology

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Helminths

Nematodes (roundworm)• Geohelminths• Strongyloides

Cestodes (tapeworm)• Taenia• Echinococcus

Trematodes (flukes)• Schistosoma• Food born trematodesLU

MC - Para

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Case 1

• Child, 5 years old• Born in Vietnam• Recently in the Netherlands, adopted child• Routine stool examination, no complains• Several larvae found

200-300 µm

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Case 2

• Female, 42 years old• Expatriate, several countries in the tropics• Since 7 years in the Netherlands• Suffering from diarrhoea (occasionally bloody)• Abdominal problems, weight loss• More than 7 stool samples examined• Finally some larvae found

200-300 µm

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Case 3

• Male, 62 years old• Born in Suriname, living in the Netherlands since 10 years• Silicosis, intensively treated with corticosteroids• Hospitalised with fever, abdominal pain, nausea• Antibiotics, but no improvement• Patient dies• Autopsy: larvae in feces and in lungs and other organs

500-550 µm

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Strongyloides global distribution

S. stercoralis: estimated 100 million people infected.Atlas of Human Infectious Diseases; H. Wertheim et al.,http://eu.wiley.com/WileyCDA/WileyTitle/productCd-140518440X.htmlLU

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Strongyloides stercoralis

Greaves et al., BMJ (2013)LUMC - P

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Clinical presentationPrimairy infection

• often asymptomatic (50%)

Chronic stage• general and mild intestinal complains• periods of epigastric pain, diarrhea• eosinophilia (75%)• larva currens (“creeping eruption”)

Hyper infection• fever• severe intestinal symptoms • severe pulmonary symptoms (48-68%)• disseminated: all organs involved

• 83-87% fatal

diagnosis and treatment (Ivermectin)to prevent hyperinfectionLUMC - P

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Natural course of Strongyloides infection

Concha et al., (2005) J Clin Gastroenterol 39:203

(not HIV/AIDS)

Eosinophilia???LUMC - P

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Immune reconstitution inflammatory syndrome - debated

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Strongyloides diagnosis

Direct smear• Not sensitive !!!!!!

Focused stool examination• Baermann procedure (alternative: cell strain)• Coproculture (alternative: agar plate)

Serology• Screening target patients

PCR (LUMC, increasingly used)

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Baermann procedure

L1 larva

L1 larva

L1 = rhabditoid larvae

genital primordium

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Differentiation between Strongyloides L1 and L3 larvae


lengths: 200-300 µm

short buccal cavity

large genital primordium

lengths: 500-600 µm

motile, slender

long esophagus (>1/3)

no sheath

L3 = filariform larvaeLUMC - P

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ology


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Strongyloides L1 larvae

genital primordium

Short buccal canal

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Differentiation between Strongyloides L1 and L3 larvae


L3 = filariform larvae

notched tail

NB:

Intermediate stages possible

Morphology deteriorates during storageLUMC - P

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Intermediate stages of Strongyloides

Sputum of patient with hyperinfection

400 µm lengthsLUMC - P

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Stool culture

L3 larva

L3 = filariaform larvae = INFECTIOUS

adult worm and L3adult wormL1 larvaLUMC - P

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Stool culture

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Skin penetration ofintestinal nematodes - tropical

Hookworm

65x40 µm

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Differentiation between Strongyloides and hookworm larvae


200-300 µm

Strongyloides

short buccal cavity

large genital premordium

Hookworm

long buccal cavity

invisible genital premordium

In case hookworm eggs hatched!!!LUMC - P

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Differentiation between Strongyloides and hookworm larvae

L3 = filariaform larvae

500-550 µm

15-20 µm

500-700 µm

25-35 µm

Strongyloides

motile, slender

long oesophagus (>1/3)

no sheath

notched tail

Hookworm

less motile, less slender

short oesophagus (<1/3)

sheath

pointed tail

Coproculture (4-7 days)!!!LUMC - P

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Differentiation between Strongyloides and hookworm L3-larvae

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direct microscopy: cases found by number of slides examined

Nielsen & Mojon 19870

2

4

6

8

10

12

14

16

18

20

5 10 15 20 25 30 35 40 +

Groove, 1989

Requires analysis of multiple samples

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Strongyloides – diagnosis Mozambique

Copro-culture

Baermann Positive Negative Total

Positive 56 14 70

Negative 27 206 233

Total 83 220 303

• Baermann = Culture (McNemar P= 0.06)

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Strongyloides diagnosis

Direct smear• Not sensitive !!!!!!

Focused stool examination• Baermann procedure (alternative: cell strain)• Coproculture (alternative: agar plate)

Serology• Screening target patients

PCR (LUMC, increasingly used)

LUMC - P

arasit

ology


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Diagnosis of Strongyloides infectionby antibody determination

Different formats

(Dis)advantages:Sensitivity vs specificity

Immigrants, screening of specific patients, chronic infections

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Real-time PCR StrongyloidesIn house tests

Verweij et al., 2009• 18S ribosomal RNA gen• Specificity 100%• Sensitivity > microscopy (?)• (Ct intensity)

• Implemented > 2006• 250-300 samples/year• 2-4 positive cases/year

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0

20

40

60

80

100

%

Cum

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ive

posi

tive s

Microscopy*

PCR

stool1 stool 2 stool 3

Peru: Strongyloides

Verweij et al (in preparation)

* Baermann

La Merced (N=188)LUMC - P

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Strongyloides stercoralis in non-endemic settingsResults Antwerp Travel Clinic N=2591

Microscopy PCR

E. histolytica/E.dispar 99

E. histolytica 13

Giardia lamblia 95 149

Cryptosporidium 12 31

Strongyloides stercoralis 3 21

(Ten Hove et al. 2009)LUMC - P

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LUMC Strongyloides PCR

Routine diagnosis: >2006• Samples/year 250-300 (3 => 1 sample)

2-4 PCR positive cases/year• Feces microscopy + PCR• Serology + PCR

• No microscopy positives missed

Post therapy: ½ - 2 weeks PCR negative

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Strongyloidiasis

• Complex life cycle, autoinfection

• Potentially fatal

• Microscopy: very low sensitivity

• Serology: limitations

• PCR

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