Immigrant Health Service

Intestinal Parasites

  • Parasites

    Findings

    Investigate

    Treatment alternatives

    Family

    Follow-up

    Repeat treatment

    Entamoeba
    histolytica


    (Amoebiasis)

    Trophozoites or cysts on stool micro (cannot distinguish between cysts of E histolytica or E. dispar

    May be associated with GIT symptoms

    FBE / differential

    Ferritin

    Fresh stool < 24 h for ELISA or PCR(if available). If this confirms E dispar, do nothing. If confirms E histolytica, treat.

    If ELISA/PCR not available, serology (IHA) for E. histolytica, although baseline positive 30% in endemic areas.

    Asymptomatic: eliminate intraluminal carriage

    Diloxanide 20 mg/kg/day (max 500 mg/dose) in 3 divided doses oral 10 days

    Paramomycin 10 mg/kg/dose 8 hourly oral 7 days (SAS medication)

    Symptomatic: Discuss with ID. Metronidazole 15 mg/kg/dose (max 750 mg) tds oral 7-10 days followed by luminal agent (as above)

    Offer screen Discuss with ID physicians if symptomatic As required for parasite persistence or reinfection
    Ascaris
    lumbricoides

    Ova on stool micro

     History of worms

    May be a/w respiratory Sx

    FBE / differential

    Ferritin

    Albendazole (weight > 10 kg) 400 mg oral stat (200 mg for patient over 6 months, up to 10 kg)

    Mebendazole 100 mg oral bd 3 days

    Offer screen, Rx siblings Repeat stool micro at follow-up (not essential) As required for parasite persistence or reinfection
    Giardia
    intestinalis

    Trophozoites or cysts on stool micro

    May be associated with GIT  symptoms

    FBE / differential

    Ferritin

    Metronidazole 30 mg/kg/dose oral (max 2 g) daily for 3 days

    Tinidazole 50 mg/kg stat dose oral (max 2 g)

    Screen  symptomatic family Repeat stool micro at follow-up (not essential) As required for parasite persistence or reinfection
    Hookworm
    (Ancylostoma or Necator)

    Ova on stool micro

    FBE / differential

    Ferritin

    Albendazole (weight > 10 kg) 400 mg oral stat (200 mg for patient over 6 months, up to 10 kg)

     Mebendazole 100 mg oral bd 3 d

    Offer screen Repeat stool micro at follow-up As required for parasite persistence or reinfection
    Strongyloides stercoralis

    (Risk of dissemination if immune suppressed)

    Larvae on stool micro

    Strongyloides serology

    FBE / differential

    Ferritin          

    Ivermectin (weight >15 kg) 200 mcg/kg dose x 2 doses, day 1 and day 14 (2 weeks apart)

    Albendazole (weight > 10 kg) 400 mg oral twice daily for 7 days 

    (200 mg for patient over 6 months, up to 10 kg)

    less effective than ivermectin -


    Offer screen

    If larvae on stool micro then repeat 3 days post treatment

    Serology & FBE at 6 months

     

    If parasites persist on stool micro repeat Rx at 2 weeks

    If serum IgG and eosinophilia persist at 3-6 months

    Children < 5 years may require monitoring and treatment with ivermectin once they are 5 years.

    Clear positive IgG

    Fresh stool micro

    FBE / diff / Ferritin

    Pulmonary or GIT symptoms

    Discuss with ID consultant urgently

    Schistosoma spp.
    (Bilharzia)

    also see Schistosomiasis guideline

    Ova on stool micro

    FBE / differential

    Schistosoma serology

    Praziquantel

    • 20 mg/kg/dose x 2 doses orally - 4 hrs apart (no upper limit)
    • 40 mg/kg total may be given as a single stat dose in children.
    Offer screen

    Stool/urine micro (x 3 specimens) at 3-6 months. Serology at 6 & 12 months

    FBE / diff at 3 months

    Persistent parasite,  increasing IgG titre 6/12 post Rx  (esp if eosinophillia)

    IgG same at 12mo

    Clear positive IgG and  negative stool micro

    Midday end urine micro for ova (lab x5738 first)

    Renal/bladder US if symptoms

    Tapeworm
    (Taenia spp)

    Proglottids or ova in faeces

    Nodules

    Check for neurological Sx (different Rx)

    FBE / differential

    Ferritin          

    Praziquantel 10 mg/kg/dose stat oral

    Rodentolepis nana (prev. Hymenolepis nana; dwarf tapeworm) requires Praziquantal 25 mg/kg/dose stat oral

    Offer screen

    Repeat stool micro 3/52 - not essential.

    As required for parasite persistence or reinfection
    Whipworm (Trichuris trichiuria)

    Ova stool micro

    May be assoc. with bloody diarrhoea, pain

    FBE / differential

    Ferritin

    Mebendazole 100 mg oral bd 3 days

    Albendazole (weight > 10 kg) 400 mg oral daily for 3 days 

    (200 mg for patient over 6 months, up to 10 kg)

    Offer screen

    Repeat stool micro 3/52- not essential

    As required for parasite persistence or reinfection

    Note:

    1. The safety of Praziquantel in children <2 yrs has not been established- Discuss with ID
    2. Albendazole tabs are chewable and soluble and trials include children 2 years and over. There is limited data on use in children aged > 6 months. Discuss if liver disease
    3. Ivermectin is used in children >15 kg
    4. Exclude pregnancy in adolescents; Praziquantal B1, Metronidazole B2, Ivermectin B3, Albendazole D.

    Notes

    Parasite infections are common; prevalence figures for presence of faecal parasites in the post arrival screen are generally around 30%. Macroscopic worms are rare, but if reported, are likely Ascaris and Taenia spp[4]. Symptoms are relatively common and include constipation (not diarrhoea) as a presenting complaint. Specific serology is available for StrongyloidesSchistosoma, Filariasis, Echinococcus, Toxocariasis and Angiostrongyliasis[4] and also Entamoeba histolytica and Taenia spp.


    Non-pathogenic parasites that may be found in stool (no action needs to be taken for these):

    • Entamoeba coli
    • Entamoeba hartmanii
    • Entamoeba gingivalis
    • Endolimax nana
    • Iodamoeba butschlii
    • Dientamoeba fragilis (NB - rarely implicated as a pathogen, discuss with ID)
    • Blastocystis hominis (NB - rarely implicated as a pathogen, discuss with ID)
    • Chilomastix Mesnili
    • Trichomonas hominis

    References

    References

    Immigrant health clinic resources. Authors: Jim Buttery and Georgie Paxton, updated March 2013, reviewed April 2016. Contact georgia.paxton@rch.org.au