History and exam
Key diagnostic factors
common
presence of risk factors
infection with other parasites
Co-infection with other parasites is common.[11]
Strongyloides infection is suggested by persisting eosinophilia after treatment for other parasites.
Giardia with eosinophilia necessitates that the diagnosis of strongyloides infection is considered.
Other diagnostic factors
common
abdominal pain
Reported by 40% of patients with chronic infection.[11]
May be misdiagnosed as irritable bowel syndrome or somatic symptom disorder.
altered bowel habit
20% of patients report stool changes such as diarrhoea or constipation.[11]
weight loss
Reported by 18% of patients.[11]
fever (hyperinfection)
A sign of hyperinfection.
signs of sepsis (hyperinfection)
In hyperinfection, patients often rapidly become critically ill with bacteraemia and sepsis caused by an enteric organism, such as Escherichia coli or enterococcus, and develop signs of septic shock.
uncommon
chronic cough
Found in 14% of patients.[11]
May be misdiagnosed as asthma.
wheezing
Found in 10% of patients.[11]
An immigrant presenting with new-onset wheezing and eosinophilia should be evaluated or treated for strongyloides infection before any corticosteroids are given.
Corticosteroids given as empirical asthma therapy can precipitate life-threatening hyperinfection.
pruritus or dermatitis
Found in 14% of patients.[11]May be misdiagnosed with psychogenic pruritus.
[Figure caption and citation for the preceding image starts]: A creeping dermatological eruption on the back of a patient with strongyloidiasisFrom the Public Health Image Library, US Centers for Disease Control and Prevention [Citation ends].
larva currens
Rapidly moving serpiginous, pruritic urticarial rash, moving 5 to 10 cm/hour.
Can chronically recur.
Incidence varies from 10% to 70% of patients dependent on burden of infection and age.[11]
urticaria
A transient urticarial rash can occur with or without larva currens.
cutaneous larva migrans
More commonly associated with the dog or cat hookworm, Ancylostoma braziliense.
Very rarely associated with strongyloides.
apparent drug reaction rash (hyperinfection)
With hyperinfection, disseminating larvae may mimic a drug reaction, with eosinophils seen on biopsy.[21]
other skin complaints
A wide variety of presentations including disseminated purpuric rash can occur in hyperinfection.
symptoms and signs of inflammatory bowel disease
Adult larvae in the duodenum may cause a severe duodenitis evident in histology with villi atrophy and plasma cells infiltration. Colonic manifestations can clinically mimic ulcerative colitis or Crohn's disease with eosinophilic granulomatous inflammation affecting the colonic wall.
Risk factors
strong
soil exposure in or migrants from an endemic area of the world
In non-endemic regions, 99% of chronic strongyloides infections are among migrants from endemic areas, particularly refugees.[11][12][13][14][15][16] Current single-dose praziquantel and albendazole campaigns in Africa do not reduce the prevalence of strongyloides infection.[17]
The greatest risk factor is cutaneous exposure to infected soil containing strongyloides filariform larvae.
Infection is endemic in many tropical and subtropical regions worldwide and in the Appalachia region of the US and in certain Mediterranean regions, especially Catalonia, Spain.
In agricultural workers, the risk of chronic infection is increased more than 50-fold compared with that of the general population in regions where the infection is endemic.[7] Military veterans, particularly with historical deployments in southeast Asia or other tropical regions, are also at risk.[9]
corticosteroids (risk of hyperinfection)
weak
international travellers
International travellers are generally at low risk for strongyloides infection. The incidence of strongyloides infection in ill returning travellers attending a European travel clinic was 0.1%.[18]
However, for those with unexplained eosinophilia and negative stool specimens, serological diagnosis is recommended.[19]
impaired immunity
Haematological malignancies, tuberculosis, and malnutrition secondary to chronic strongyloides diarrhoea are all other risk factors for hyperinfection.[24]
solid-organ transplant recipient
Cases of donor-derived infection have been reported, albeit rarely, in recipients who have received organs from donors in endemic regions. Donor-derived strongyloidiasis has a high mortality rate.[10]
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