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Intestinal Nematodes Intestinal nematodes as seen in faeces, and Anisakis spp. 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 • 807-1221 x 106 • Trichuris trichiura • 604-795 x 106 • Necator americanus and • 576-740 x 106 Ancylostoma duodenale • Strongyloides stercoralis • 30-100 x 106 • Enterobius vermicularis • 4-28% of children • Toxocara canis and • 2-80% of children Toxocara cati Bethony J. et al. 2006. Lancet 367:1521- 1532. High worldwide prevalence, except Europe, North America, Australia, and Japan Bethony J. et al. 2006. Lancet 367:1521-1532. Species Length Daily egg Location in Lifespan (mm) output host (years) Ascaris lumbricoides 150- 200000 Small 1 400 intestine Trichuris trichiura 30-50 3000-5000 Caecum and 1.5-2 colon Necator americanus 7-13 9000-10000 Upper small 5-7 Ancylostoma duodenale 8-13 25000-30000 intestine Courtesy J. Vandepitte Bethony J. et al. 2006. Lancet 367:1521-1532. •Ascariasis – Verminous pneumonia (Löffler syndrome) – Lactose intolerance – Intestinal obstruction – Hepatopancreatic ascariasis Bethony J. et al. 2006. Lancet 367:1521-1532. • Trichuriasis – Anterior end embedded in epithelial tunnels within the intestinal mucosa – Colitis – “dysentery syndrome” – Rectal prolapse Bethony J. et al. 2006. Lancet 367:1521-1532. • Hookworm – Cough – Intestinal blood loss – Iron-deficiency anaemia (> 40 adult worms) – Protein malnutrition 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-infectious Enterobius vermicularis Hymenolepis nana Strongyloides stercoralis Courtesy CDC Ascaris lumbricoides Adult male worm, with a curved tail (Unstained). Ascaris lumbricoides Adult worm (Unstained). Ascaris lumbricoides Several adult worms. 3 cm Löffler syndrome • Second week after ingestion of eggs, larvae invade lung tissue. • Immune-mediated hypersensitivity response. • In severe cases eosinophilic pneumonia (Löffler syndrome). Maguire J.H. 2010. In Mandell et al. Courtesy CDC Toxocara canis Several adult worms, smaller than A. lumbricoides. 1 cm Toxocara canis (cati) • Visceral larva migrans (VLM). • Children < 6 years. • Liver, lung, skin, ... • Ocular larva migrans. – T. canis – Unilateral eye involvement – Albendazole, thiabendazole Nash T.E. 2010. In Mandell et al. Cutaneous larva migrans • Creeping eruption. • Serpiginous, reddened, elevated, pruritic skin lesions. • Ancylostoma braziliense (dog and cat hookworm), Ancylostoma caninum, ... • Eosinophilic inflammatory infiltrate. • Treatment of choice is ivermectin. An alternative is albendazole. Nash T.E. 2010. In Mandell et al. Courtesy CDC 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). 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 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 Courtesy CDC Enterobius vermicularis Tail from a gravid female filled with eggs (Unstained). Enterobius vermicularis Pin-shaped tail from a female pinworm (Unstained). Enterobius vermicularis Front end with alae from a female (Unstained). Enterobius vermicularis Asymmetric embryonated infective egg in faeces with thin double shell. Contains a folded larva. Length: 55 μ (Unstained). Enterobius vermicularis Asymmetric embryonated infective egg in faeces with thin double shell. Contains a folded larva. Length: 55 μ (Unstained). Enterobius vermicularis Asymmetric eggs in faeces with a thin double shell, containing a folded larva (Unstained). Enterobius vermicularis Asymmetric eggs with a thin double shell in the female worm (Unstained). Courtesy CDC Trichuris trichiura Lemon-shaped egg, measuring 50-55 μm, with a brown-yellowish outer shell and two hyaline polar plugs in faeces (Unstained). Trichuris trichiura Lemon-shaped egg, measuring 50-55 μm, with a brown-yellowish outer shell and two hyaline polar plugs in faeces (Unstained). Trichuris trichiura Lemon-shaped egg, measuring 50-55 μm, with a brown-yellowish outer shell and two hyaline polar plugs in faeces (Unstained). Trichuris trichiura Lemon-shaped egg, measuring 50-55 μm, with a brown-yellowish outer shell and two hyaline polar plugs in faeces (Unstained). Trichuris trichiura Lemon-shaped egg, measuring 50-55 μm, with a brown-yellowish outer shell and two hyaline polar plugs in faeces (Lugol stain ). Courtesy Peters W. & Gilles H. Ascaris lumbricoides Fertile bile-stained egg with a thick, mammillated shell, measuring 55-75 μm (Unstained). Ascaris lumbricoides Fertile bile-stained egg with a thick, mammillated shell, measuring 55-75 μm. The microscope has been focused on the outer shell (Unstained). Ascaris lumbricoides “Decorticated” fertile egg from a subphrenic abscess. The mammillated layer is absent (Unstained). Ascaris lumbricoides This infertile egg is elongated and larger (85-95 μm) than a fertile egg (Unstained). Ascaris lumbricoides This infertile egg is elongated and larger (85-95 μm) than a fertile egg (Unstained). Ascaris lumbricoides This infertile egg is elongated and larger (85-95 μm) than a fertile egg (Unstained). Courtesy CDC Hookworm egg Hookworm egg with four blastomeres. Eggs of Ancylostoma duodenale and Necator americanus are indistinguishable (Unstained). Hookworm egg Older hookworm egg with many blastomeres. Eggs of A. duodenale and N. americanus are indistinguishable (Lugol stain). Courtesy CDC Strongyloides stercoralis First stage rhabditiform larva in faeces. The length varies from 180 to 380 μm (Unstained). Strongyloides stercoralis Rhabditiform larva in faeces. The length varies from 180 to 380 μm(Unstained). Strongyloides stercoralis Rhabditoid larva in faeces with the typical esophagal bulb (Unstained). Strongyloides stercoralis Infective-stage filariform larva in faeces. The tail has a typical notched appearance. Length up to 630 μm (Unstained). Strongyloides stercoralis The free-living (rhabditoid) female (length 1.0 to 1.7 mm) has a short vulva that opens near the middle of the ventral side (Unstained). Trichostrongylus colubriformis Large egg (75-95 μm) with a thin shell, containing a morula (Unstained). Anisakis sp. Larvae in fish. • Nematode of crustaceans, fish, marine mammals (stomach). • The Netherlands, Northern Europe, Japan. • Linked to the consumption of raw fish. • Haringworm (NL) in the stomach or duodenum of man (eosinophilic granuloma). • Removed by surgery, mebendazole (?). Pseudoterranova decipiens An uninvited dinner guest • Home-cooked codfish dinner on the Good Friday holiday. • Gill C. & Hamer D. • 2005. CID. 1764 & 1810- 1811. Courtesy CDC.
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