Immigrant Health Service : Intestinal Parasites

Intestinal Parasites

Parasites	Findings	Investigate	Treatment alternatives	Family	Follow-up	Repeat treatment
Amoebiasis	Trophozoites or cysts on stool micro (cannot distinguish between cysts of E. histolytica/dispar/ moshkovskii). Multiplex PCR distinguishes spp May be associated with GIT symptoms, including colitis	FBE/differential Fresh stool <24 h for ELISA or PCR if available. If E dispar confirmed - nothing. If E histolytica confirmed treat. If ELISA/PCR not available, serology (IHA) for E. histolytica, although baseline positive 30% endemic areas.	Asymptomatic: eliminate intraluminal carriage Paramomycin 10mg/kg/dose (max 500mg) 8 hourly oral 7 days (SAS medication) Symptomatic: Discuss with ID. Metronidazole 15mg/kg/dose (max 600mg) tds oral 7 days followed by luminal agent (as above). Higher doses in severe disease/confirmed liver abscess.	Offer screen	Discuss with ID physicians if symptomatic	As required for parasite persistence or reinfection
	Ova on stool micro History macroscopic worms May be a/w respiratory symptoms	FBE/differential	Albendazole (weight >10kg) 400mg oral stat (200mg oral stat if >6 months, <10kg) Mebendazole 100mg oral bd 3 days (50mg oral bd 3 days if <10kg)	Offer screen, Rx siblings	Repeat stool micro at follow-up (not essential)	As required for parasite persistence or reinfection
	Trophozoites or cysts on stool micro May be associated with GIT symptoms.��Asymptomatic carriage in immune competent may not need treatment.	nil	Metronidazole 30mg/kg (max 2g) oral daily for 3 days OR 10mg/kg (max 400mg) oral 8-hourly for 3 days Tinidazole��discontinued in 2020. Nitazoxanide, albendazole, mebendazole or paromomycinarealternatives	Screen symptomatic family	Repeat stool micro at follow-up (not essential)	As required for parasite persistence or reinfection
**Ancylostoma or Necator**	Ova on stool micro	FBE/differential Ferritin	Albendazole (weight >10 kg) 400mg oral stat (200mg oral stat if >6 months, <10kg) Mebendazole��100mg oral bd 3 days (50mg oral bd 3 days if <10kg)	Offer screen	Repeat stool micro at follow-up	As required for parasite persistence or reinfection
(Risk of dissemination if immune suppressed) See guideline	Strongyloides serology is primary screen Larvae on stool micro	Strongyloides serology FBE/differential	Ivermectin (weight >15 kg) 200mcg/kg (no upper limit) x 2 doses, day 1 and day 14 (2 weeks apart). More doses if immunocompromised Albendazole (weight >10 kg) 400mg oral bd for 3 days + repeat course after 14 days (200mg oral bd as above if >6 months, <10kg) 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 If serum IgG & eosinophilia persist at 3-6 months Children <15kg may require monitoring & Rx with ivermectin once 15kg
	Clear positive IgG	Fresh stool micro FBE/differential
	Pulmonary or GIT symptoms	Discuss with ID consultant urgently
(Bilharzia) see guideline	Schistosoma serology is primary screen (more sensitive for S. mansoni & S. haematobium than others) Ova on stool micro	FBE/differential	Praziquantel��20mg/kg x 2 doses oral, 4 hrs apart (no upper limit)�� 40mg/kg total may be given as a stat dose in children	Offer screen	If initial stool or urine micro+ repeat at 3-6 months (x 3 specimens) FBE/differential at 3 months Serology at 12 months	Persistent parasite, increasing IgG titre 6 months post Rx (especially if eosinophillia) IgG same at 12mo
(Bilharzia) see guideline	If positive serology - check stool COP and end urine If positive stool or urine, further investigations for end-organ damage	Midday end urine micro for ova (lab x5738 first) Renal/bladder US (urinary) or liver US & doppler (gut)		Offer screen
Tapeworm (pig) or (beef)	Proglottids or ova in faeces Nodules Check neurological symptoms/epilepsy Hx (T. solium,��different Rx)	FBE/differential Ferritin	Praziquantel 10mg/kg oral stat (no upper limit) Niclosamide��50mg/kg (max 2g) oral stat (Rodentolepis) nana��(dwarf tapeworm) - Praziquantal 25mg/kg oral stat (no upper limit)	Offer screen	Repeat stool micro at 3 weeks - not essential.	As required for parasite persistence or reinfection
Trichuris trichiuria	Ova stool micro May be associated with bloody diarrhoea, pain or rectal prolapse	FBE/differential Ferritin	Mebendazole 100mg oral bd 3 days (50mg oral bd 3 days weight <10kg) Albendazole 400mg oral daily for 3 days (200mg oral daily for 3 days >6m, weight <10kg)	Offer screen	Repeat stool micro at 3 weeks - not essential	As required for parasite persistence or reinfection
Note: - Australian guidelines now providing dosing for children 1-18y (although limited evidence <4 years, some trials age 2-5 years) - discuss with Infectious diseases for younger children. for children >5kg - (150mg dispersible tablets) Albendazole tabs are chewable and soluble, in children 12 months - 12 years (as annual or biannual 400mg dose) where baseline prevalence of soil transmitted infection is 20%+. Biannual dosing recommended if baseline prevalence is >50%. Discuss if liver disease Ivermectin is used in children >15 kg Exclude pregnancy in adolescents; Praziquantal B1, Metronidazole B2, Ivermectin B3, Albendazole D.

Background

Parasite infections are common; prevalence figures for presence of faecal parasites in post arrival refugee health screening in Australia are generally around 30% - see ��prevalence summary. Macroscopic worms are very rare, but if reported, are likely Ascaris and Taenia spp.⁴��Ascarids may be seen again in new arrivals from Gaza.

Symptoms are relatively common and include both diarrhoea and constipation as a presenting complaint. Our clinical experience is that many patients have been 'retrospectively' symptomatic - reporting resolution of grumbling abdominal pain and solid stool for the first time after parasite treatment. In a , 39.8% had any parasites, 26.8% had faecal pathogens, and 78.5% of all faecal specimens were noted to be unformed. We have definitely seen��Trichuris��presenting with rectal prolapse (and would always check faecal COP for this aetiology if this is a presenting concern). Specific serology is available for Strongyloides, Schistosoma, Filariasis, Echinococcus, Toxocariasis, Angiostrongyliasis,⁴ Entamoeba histolytica and Taenia spp. Please see separate guidelines for malaria (statewide CPG), malaria screening,��Schistosoma and Strongyloides��infections, and the superb , including . Seek specialist advice for complicated parasite infections, including hydatid disease, liver abscess, liver flukes, leishmaniasis and others.��

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

(Note: rarely implicated as a pathogen, discuss with ID if symptomatic and repeated specimens high growth)
(Note: rarely implicated as a pathogen, discuss with ID if symptomatic and repeated specimens high growth)

Resources

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References

Immigrant health clinic resources. Authors: Jim Buttery and Georgie Paxton, updated March 2013, reviewed Jan 2024. Contact georgia.paxton@rch.org.au

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