Helminth: Nematodes

Helminth: Nematodes

1. Ascaris lumbricoides

   • Forms
     • Eggs in faeces
     • Develop in soil
     • Transmission to mouth
   • life cycle
     • Larval migration
       • Pneumonitis
         • 4-16 days post infxn
           • fever
           • cough
             • Expectorant
               • may reveal larvae
           • Eosniophilia infiltrates
           • last 3 weeks
       • Expectorant maybe swallowed back
         • Can settle in small intestine
       • Other
         • Neurological disorders
         • Granulomatous reaction
   • Symptoms
     • NONE
     • Heavy infection
       • malnutrition, failure to thrive
     • Obstructive
       • vomitting
       • RARE
         • intestinal obstruction
         • volvulus
         • perforation
         • peritonitis
   • Complication
     • Granulomatous rxn
     • Ductal blockage
       • BIliary colic
       • appendecitis, pancreatitis
     • Wandering worms
       • Nasogastric tube/ sinus
   • Dx & Tx
     • Dx
       • Faecal examinatiaon
         • Adult worms in stool
         • Egg in stool
       • Wandering worm
         • Mouth
         • Nose
       • Radiology
         • Barium meal
     • Tx
       • Single dose
         • Albendazole
           • 2-5y/o -200mg
           • >5y/o -400mg
         • Mebendazole
           • 500mg
           • Not for complication (no absorbed)
         • Levamisole
           • 2.5mg/kg
         • Pyrantel pamoate
           • 10mg/kg

2. Trichuris trichiura

   • Intro
     • Eggs ingested (anus to mouth)
     • whip shaped larvae release in caecum
       • handle buried in caecum, rectum,colom
     • Feed on tissue fluid juices
   • Symptoms
     • asymptomatic (light infxn <1000 eggs)
     • Pruritis ani
       • irritation of the skin near the rectum
     • IBD like symptoms
       • diarrhoea
       • rectal bleeding
     • Pain RIF
     • rectal prolapse in children
   • Dx&Tx
     • Dx
       • egg in stool
       • Rectal prolapse
       • Eosinophila
       • Adult worm up to 4cm
     • Tx
       • Albendazole 400mg once
       • Mebendazole 500mg once

3. Strongyloides stercoralis

   • Parasite
     • Mature in small intestine
     • Rhabdatidiform larvae
       • passed in stool
       • non infectious
       • indepenent life cycle in soil
     • Possibility
       • auto infective cycle
         • infection persist for decades
         • larvae is infective
           • cause increasing infection
       • Larva currens
         • itchy cutaneous
         • Serpiginous wheal + local flare
         • comes n goes hrly
   • Clinical symptoms
     • often asymptomatic
     • Primary infection
       • Rash x 3 weeks
       • resp symptoms
       • abdominal discomfort + diarrhoea
     • Chronic Infection
       • Persist for decades
       • Mild
         • non spec GI upset
       • Abdominal Pain
         • @epigastric+RUQ
       • Weight loss
     • Complicated Strongyloidiasis
       • Spruce like symp
         • Steatorrhoea
         • Protein losing enteropathy
         • Low albumin, oedema
       • Abdominal Pain + vomiting + diarrhoea
       • Sepsis-like
       • Obstruction/ ileus(lack of movement)
       • Pulmonary
         • SOB+cough+wheeze
         • pneumonitis
         • Pulmonary abscess
       • Neurological
   • Hyperinfection syndrome
     • Overwhelmin infxn
       • immune deficiency
     • corticosteroids
     • immunosuppressant drugs
       • post transplt
       • chemo
     • HTLV-1 (malnutrition)
     • clinical
       • severe bloody diarrhoea
       • bowel inflammation (micro-perforation)
       • gram -ve sepsis
       • meningitis/enchepalitis
       • pulmonary exudate/ haemoptysis, effusion
       • tx antihemithics
   • Dx/Tx
     • Dx
       • Clinical
         • Diarrhoea
         • Adominal pain
         • Urticaria
         • Larva currens
       • Lab
         • Eosinophilia
         • inc IgE
         • Culture - charcoal medium
       • Serology
         • ELISA
     • Tx
       • Ivermectin
         • 200mcg/kg/d x 3 days
       • Albendazole
         • 400mg/d 400mg/BD x 3 days/ 7 days if chronic
       • Thiabendazole
         • 25mg/kg BD x 3 days

4. Hookworms

   • Parasite
     • Anacylostoma doadenale & Necator americanus
       • Non infxn egg in stool
       • Hatch in warm damp soil
       • larvae penetrate skin
       • Hookworm
         • LUNG STAGE
           • Filariform larvae penetrate skin
         • Have mouth, teeth,pharynx, oesophagus + gut
         • Suction
           • Attach to small intestine
   • Primary infection
     • Ground itch at site
     • Lung stage (1-2 weeks)
       • dry cough
       • Wheeze
       • Fever
       • eosinophilia
     • Self limiting 2-3 mo
   • Adult worm
     • Blood suckers
     • 1-9 yrs
     • <25 worm insignificant
       • 500-1000 cause disease
   • Signs (if many)
     • Eosinophilia
     • Fe def anemia
     • egg in stool microscopy
   • Tx
     • Albendazole
     • Mebendazole
     • Pyrantel pamoate
     • treat iron Fe def

5. Prevention

   • Antihemithic drugs
   • sanitation
   • personal hygine
   • Shoes