Nematodes
- subgroup of Helmiths (parasitic worms)
- some may have both intestinal and extra-intestinal stages.
- classified as to most pronounced feature of life cycle and it’s position
- eosinophilia is hallmark of infections involving extra-intestinal stages
Intestinal (most pronounced here)
Pinworm- Enterobius vermicularis
Ø DIAGNOSIS: scotch tape preparation
Ø Infective stage: Egg
Whipworm- Trichuris trichiura; burrow into epithelial cells of colon
Ø DIAGNOSIS: Stool examination
Ø Infective stage: egg
Ø FOOTBALL SHAPED egg
Ascariasis- Ascaris lumbricoides; mechanical obstruction; pneumonitis
Ø DIAGNOSIS: Stool examination
Ø Infective stage:egg
Ø 2nd stage larvae can be in lungs
Ø large thick, walled egg
Hookworms
- Necator americanus
- Ancylostoma duodenale
Ø causes malabsorption and altered motility
Ø DIAGNOSIS: stool examination
Ø Infective stage: LARVA
Ø don’t go barefoot
Ø Filariform larvae
Ø can become anemic due to blood loss
Strongyloidiasis- Strongyloides stercoralis
Ø DIAGNOSIS: stool examination of larvae or duodenal aspirate
Ø Infective stage: RHABIDIFORM LARVA
Ø can be infected from skin penetration
All of the above except Strongyloidiasis is TREATED with Mebendazole. Strongyloidiasis is TREATED with Thiabendazole and an Anitbiotic called Ivermectin
Extra-intestinal (most pronounced here)
Trichinella spiralis- trichinosis
Ø TRANSMISSION: larva of infected meat
Ø intestinal phase involves larval and adult forms
Ø Extraintestinal phase involves larval forms
Ø DIAGNOSIS: 1. Serology 2. Muscle biopsy
Ø TREATMENT: antiinflammatory agents: Salicylates and corticosteroids
Extraintestinal
“Non-human” hookworms (CLM- cutaneous larvae migrans)
- Ancylostoma brasiliensis- cat
- Ancylostoma caninum- dog
Ø TRANSMISSION: Filariform larvae
Ø causes skin lesions
Ø DIAGNOSIS: clinical based on skin lesions
Ø TREATMENT: thiabendazole or dry ice at advancing area
Ø Migrates in larval form
“Non-human ascarids (Visceral larval migrans- VLM)
- Toxocara canis
Ø TRANSMISSION: ingestion of eggs of dog ascarid
Ø Causes: fever, chronic hyper eosinophilia, hepatomegaly, pulmonary inflitration
Ø DIAGNOSIS: clinical
Ø TREATMENT: Thiabendazole
Tags: Ascaris lumbricoides; mechanical obstruction, brasiliensis, caninum, Enterobius vermicularis, eosinophilia, hookworms, parasitic worms, pinworm, pneumonitis, Rhabidiform larva, Strongyloides stercoralis, Thiabendazole, Trichinella spiralis
