Helminths in faeces

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  • Helminths in faeces

    General considerations

  • Parasitic Disease

    Number of Infections(millions)

    Morbidity (%)

    Mortality(number)

    (%)

    Ascariasis 1,472 23 60,0000.004Hookworm infections 1,298 12

    65,0000.005

    Lymphatic filariasis 120 37

    Onchocerciasis 18 4.2 45,0000.25

    Schistosomiasis 200 10 20,0000.01

    Trichuriasis 1,049 21 10,0000.001Courtesy The Ohio State University

  • Bethony J. et al. 2006. Lancet 367:1521-1532.

    Soil-transmitted helminth infections: ascariasis, trichuriasis, and

    hookworm

  • Bethony J. et al. 2006. Lancet 367:1521-1532.

    Ascaris lumbricoides Trichuris trichiura Necator americanus and

    Ancylostoma duodenale Strongyloides stercoralis Enterobius vermicularis Toxocara canis and

    Toxocara cati

    807-1221 x 106

    604-795 x 106

    576-740 x 106

    30-100 x 106

    4-28% of children 2-80% of children

  • Bethony J. et al. 2006. Lancet 367:1521-1532.

    High worldwide prevalence, except Europe, North America, Australia,

    and Japan

  • Helminths: morbidity (%) mortality (n)

    Ascaris lumbricoides Ancylostoma-Necator Onchocerca volvulus Schistosoma spp. Trichuris trichiura

    23 60 000 12 65 000 4.2 45 000 10 20 000 21 10 000

    www.biosci.ohio-state.edu/parasite/morbidity.html

  • Helminths in faeces

    Adult worms (Ascaris lumbricoides, Enterobius vermicularis,...), fragments of worms (proglottids of Taenia saginata,...).

    Eggs and larvae.

  • Ascaris lumbricoides Adult male worm, with a curved tail (Unstained).

  • Ascaris lumbricoides Adult worm (Unstained).

  • Ascaris lumbricoides

    Fertile bile-stained egg with a thick, mammillated shell, measuring 55-75 m (Unstained).

  • Strongyloides stercoralis

    First stage rhabditoid larva in faeces. The lenght varies from 180 to 380 m (Unstained).

  • Eggs of helminths (worms) in faeces

    Eggs with an operculum: trematodes.

    Eggs with a spine: schistosomes.

    Eggs having hooklets (hexacanth larva of Taenia saginata): cestodes.

    Eggs sometimes containing a larva: nematodes or roundworms.

    Size is essential for identification.

  • Ocular micrometer disk

    Each objective must be calibrated with reference material.

    Can be roughly checked with a counting chamber, with RBCs ...

  • Courtesy Ash L.R. & Orihel T.C.

  • Courtesy CDC

  • Concentration procedures

    Are base on differences in specific gravities

    Two most commonly used methods:

    zinc sulfate flottation method

    formalin-ether sedimentation method

  • Formalin-Ethyl Acetate (Ether)

    Sedimentation Concentration (Modified

    Ritchie-Method)

  • Specific gravities

    S.G. of Zn-sulfate 33 %: 1.180 S.G. of formol-solution 10 %: 1.019 S.G. of ether: 0.714 S.G. of parasites: Ancylostoma 1.055; Giardia

    1.060; Entamoeba histolytica (coli) and Endolimax nana 1.065 - 1.070; Ascaris 1.110; Trichuris 1.150, Chilomastix mesnili 1.180; Ascaris (unfertilized) 1.200 (Bailenger, 1965).

  • Editorial Commentary

    One or multiple (three) specimens tested. Lack of clear evidence. If testing is worth doing it is worth doing

    well.

    Jon. E. Rosenblatt. 2006. CID. 42:979-980.

  • Estimation of worm burdens through egg counts

    Direct fecal smear of 2 mg (Beaver) Number of adult worms correlated to

    number of eggs present Ascaris lumbricoides 1/2 Trichuris trichiura 10 Ancylostoma duodenale 5 Necator americanus 10 to 20

  • Eosinophilia > 10%With helminths,insects (myasis),

    not with protozoa excepting Isospora belli and Dientamoeba

    fragilis (with pinworms?)

  • Charcot-Leyden

    Crystals

    associated with

    eosinophils

    found in faeces

    or sputum

  • Charcot-Leyden

    Crystals

    associated with

    eosinophils

    found in faeces

    or sputum

  • Auto-infectiousEnterobius vermicularis

    Hymenolepis nana

    Strongyloides stercoralis