Paeds · infectious-diseases
Parasitic infections in children
Also known as Intestinal parasites in children · Helminthiasis · Soil-transmitted helminth infection · Giardiasis · Enterobiasis · Scabies · Pediculosis capitis · Toxocariasis
Fellowship topic on parasitic infections in children: the broad landscape of protozoa (Giardia), soil-transmitted helminths (Ascaris, hookworm, Strongyloides), schistosomiasis, toxocariasis, cutaneous larva migrans, and the ectoparasites scabies and pediculosis; the faecal-oral, skin-penetration and direct-contact routes of acquisition; the clinical patterns from anal pruritus and chronic diarrhoea to iron-deficiency anaemia, visceral toxocariasis and creeping eruption; diagnosis by stool microscopy, antigen testing, tape test, skin scraping and clinical recognition; and the stepwise management from mebendazole and albendazole for intestinal worms to tinidazole for giardiasis, ivermectin for strongyloidiasis and scabies, permethrin for ectoparasites, and the essential public-health principles of treating households, checking glucose-6-phosphate dehydrogenase status, and avoiding steroids alone in Strongyloides infection.
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Target exams
Red flags
- A child with chronic diarrhoea, flatulence, foul-smelling greasy stools and weight loss has giardiasis until stool antigen or microscopy proves otherwise, and the infection is easily missed because routine stool culture does not detect Giardia cysts
- Any child receiving corticosteroids or about to start immunosuppression who has lived in or travelled to a tropical area must be screened and treated for Strongyloides stercoralis beforehand, because steroids can trigger fatal hyperinfection through auto-infection
- Intense generalised pruritus worse at night, with burrows in the finger webs, wrists and axillae and a household contact with the same rash, is scabies; crusted scabies in an immunocompromised or disabled child is highly contagious and demands isolation plus ivermectin
- A toddler with hepatosplenomegaly, eosinophilia, fever and wheeze who plays in soil contaminated by dog or cat faeces has visceral toxocariasis, which can mimic asthma, lymphoma or retinoblastoma when the eye is involved
- Iron-deficiency anaemia in a child from a resource-limited setting or an Indigenous community, without an obvious dietary cause, should prompt stool examination for hookworm, which causes chronic occult blood loss through the intestinal wall
- A returned traveller with haematuria or dysuria, or with hepatosplenic disease and eosinophilia, must be assessed for schistosomiasis, because chronic untreated infection leads to portal hypertension and bladder cancer
Life stages
Care settings
Clinical exam formats
Board mappings
- Takes a focused exposure, travel, and household contact history in a child with pruritus, diarrhoea, or unexplained anaemia
- Selects the correct diagnostic test for each parasite: stool antigen for Giardia, tape test for pinworm, skin scraping for scabies
- Prescribes first-line antiparasitics: mebendazole for pinworm and ascaris, tinidazole for giardiasis, permethrin for scabies and lice
- Recognises Strongyloides hyperinfection risk in immunosuppression and screens at-risk children before corticosteroids
- Distinguishes visceral toxocariasis from other causes of eosinophilia and hepatomegaly
- Manages returned travellers with schistosomiasis, including praziquantel therapy and follow-up serology
- Recognition and treatment of common paediatric parasitic infections: giardiasis, enterobiasis, scabies
- Diagnosis of soil-transmitted helminth infection and iron-deficiency anaemia
- Public health principles of treating household contacts and school outbreaks
- Communication of the diagnosis of scabies or lice with attention to stigma, school attendance, and contact tracing
- Counselling families on household treatment, environmental cleaning, and re-treatment schedules
- Bedside tape test and skin examination demonstrating burrows and nits
- Level 1: Recognises common parasitic presentations including pruritus ani, chronic diarrhoea, and pruritic rash
- Level 2: Diagnosis and treatment of giardiasis, enterobiasis, and scabies; knows when to refer
- Level 3: Management of strongyloidiasis, schistosomiasis, and crusted scabies in complex children
- Life cycles of Giardia, Ascaris, Enterobius, and Strongyloides and how they determine clinical presentation
- Mechanism of iron-deficiency anaemia in hookworm and of auto-infection in Strongyloides
- Drug mechanisms and dosing of mebendazole, albendazole, ivermectin, and permethrin
- History and examination of a child with chronic diarrhoea and weight loss
- Communication of scabies management including household contacts and school exclusion
- Assessment of the returned traveller with possible schistosomiasis or strongyloidiasis
- Diagnosis and treatment of common intestinal parasitic infections in children
- Screening of newly arrived refugees and internationally adopted children for parasites
- Recognition and management of scabies and pediculosis capitis
- Recognition and treatment of giardiasis, enterobiasis, and soil-transmitted helminths
- Public health implications of ectoparasite outbreaks in schools and childcare
- Screening for Strongyloides before immunosuppression
- Common paediatric parasitic infections seen in Canada including giardiasis, pinworm, and scabies
- Screening of newly arrived immigrant and refugee children for parasitic infection
- Public health notification and school exclusion policies for scabies and pediculosis
Overview & Definition
Parasitic infections in children encompass a broad group of diseases caused by protozoa, helminths, and ectoparasites that remain among the most common infections of childhood worldwide. In resource-rich settings such as Australia and New Zealand they are frequent in primary care and emergency presentations, while in resource-limited settings they contribute significantly to malnutrition, anaemia, impaired growth, and lost educational opportunity. The paediatric vulnerability arises from immature hygiene behaviours, oral exploration, close physical contact in childcare and school, and exposure to soil, sandpits, and animals. [1]
The organisms divide cleanly into three functional groups that dictate how the clinician thinks at the bedside. Protozoa such as Giardia lamblia are single-celled organisms acquired by the faecal-oral route that colonise the intestinal lumen. Helminths include the soil-transmitted roundworms Ascaris lumbricoides, hookworm, and Strongyloides stercoralis, the pinworm Enterobius vermicularis, the tissue-migrating Toxocara species, and the blood fluke Schistosoma. Ectoparasites, principally the scabies mite Sarcoptes scabiei and the head louse Pediculus humanus capitis, live on the skin or hair and cause disease through burrowing and hypersensitivity. [2]
The cardinal principle is that most parasitic infections are treatable with simple, safe, oral or topical therapy, but the diagnosis is missed because the clinician did not think of it. A child with chronic diarrhoea may be labelled irritable bowel syndrome when Giardia antigen was never sent. A child with iron-deficiency anaemia may be given iron supplements alone when stool microscopy would have found hookworm ova. The travel history, household and animal exposures, and the recognition of classic clinical patterns are the hinge of every encounter. [3]
References12ShowHide
- [1]Jourdan PM; Lamberton PHL; Fenwick A; Addiss DG Soil-transmitted helminth infections. Lancet, 2018.PMID 28882382
- [2]Bethony J; Brooker S; Albonico M; Geiger SM; Loukas A; Diemert D; Hotez PJ Soil-transmitted helminth infections: ascariasis, trichuriasis, and hookworm. Lancet, 2006.PMID 16679166
- [3]Leung AKC; Leung AA; Wong AH; Sergi CM; Kam JK Giardiasis: An Overview. Recent Pat Inflamm Allergy Drug Discov, 2019.PMID 31210116
- [4]Leung AKC; Lam JM; Hon KL; Barankin B; Leung AAA Pinworm (Enterobius Vermicularis) Infestation: An Updated Review. Curr Pediatr Rev, 2025.PMID 38288810
- [5]Sunderkötter C; Wohlrab J; Hamm H Scabies: Epidemiology, Diagnosis, and Treatment. Dtsch Arztebl Int, 2021.PMID 34615594
- [6]Fernando DD; Mounsey KE; McCarthy JS Scabies. Nat Rev Dis Primers, 2024.PMID 39362885
- [7]Leung AK; Fong JH; Pinto-Rojas A Pediculosis capitis. J Pediatr Health Care, 2005.PMID 16286223
- [8]Ma G; Holland CV; Wang T; Hofmann A; Fan CK; Maizels RM; Hotez PJ; Gasser RB Human toxocariasis. Lancet Infect Dis, 2018.PMID 28781085
- [9]Loukas A; Hotez PJ; Diemert D; Yazdanbakhsh M; McCarthy JS; Correa-Oliveira R; Croese J; Bethony JM Hookworm infection. Nat Rev Dis Primers, 2016.PMID 27929101
- [10]Colley DG; Bustinduy AL; Secor WE; King CH Human schistosomiasis. Lancet, 2014.PMID 24698483
- [11]Buonfrate D; Bradbury RS; Gobbo F; Sequi M; Esposto AD; Giorli G; Torresi J; Oskam L; Krolewiecki A; Bisoffi Z Human strongyloidiasis: complexities and pathways forward. Clin Microbiol Rev, 2023.PMID 37937980
- [12]Escobedo AA; Almirall P; Alfonso M; Pitueles P; Teran G; Cordovi RA; Nunez FA Efficacy of 5-nitroimidazole compounds for giardiasis in Cuban children: systematic review and meta-analysis. Infez Med, 2019.PMID 30882380