Differentials
Hookworm
SIGNS / SYMPTOMS
No differentiating signs or symptoms.
Hookworm has a finite life span of <5 years. Thus, in people residing in a developed country for 5 years or more, strongyloides is the more likely diagnosis as it carries on lifelong autoinfection within the human body without need for re-exposure.
INVESTIGATIONS
In stool specimens having delayed processing time, hookworm ova may hatch with larvae that appear similar to strongyloides larvae. Therefore, it is important to determine whether a delay in processing occurred. Repeat testing may be necessary.
Hookworm therapy is insufficient to eradicate strongyloides.
Eosinophilia, when present, is a marker of treatment failure.
Schistosomiasis
SIGNS / SYMPTOMS
More likely in people emigrating from Africa.
INVESTIGATIONS
Dipstick urinalysis may be positive for blood in urinary schistosomiasis.
Standard stool or urine ova and parasite exam will differentiate the conditions, although it is a relatively insensitive test for diagnosis of schistosomiasis.
Serologic testing is available and may differentiate the conditions.
Filariasis
SIGNS / SYMPTOMS
May be no differentiating signs or symptoms.
More likely to cause dermatitis and nodules.
Loa loa more likely to present with visual defects and signs of eye infection.
INVESTIGATIONS
Forms part of the differential diagnosis of unexplained eosinophilia.
Giemsa-stained blood smear exam and serologic testing are used primarily for diagnosis.
Microfilariae identified on peripheral blood smear (a late-night sample increases detection rates).
Amebiasis
SIGNS / SYMPTOMS
No differentiating signs or symptoms.
INVESTIGATIONS
Identification of ameba in stool samples.
Unlike strongyloides infection, Entamoeba histolytica and Entamoeba dispar do not cause eosinophilia.
Asthma
SIGNS / SYMPTOMS
Both conditions may result in cough and wheeze and may at times be asymptomatic.
Asthma is less likely to present with abdominal or skin features.
Strongyloides infection more likely in a person migrating from an endemic area.
INVESTIGATIONS
Stool ova and parasite exam and serology are negative.
The presence of eosinophilia in a high-risk person (such as a person migrating from an endemic area) alerts the physician to look for other causes apart from asthma, especially when the asthma-like symptoms are of new-onset in an adult.
Irritable bowel disease
SIGNS / SYMPTOMS
Both conditions may cause abdominal pain and altered bowel habit.
Strongyloides infection more likely in a person migrating from an endemic area.
INVESTIGATIONS
Eosinophilia not present.
Somatic symptom disorder
SIGNS / SYMPTOMS
May be no differentiating features.
Strongyloides infection more likely in a person migrating from an endemic area.
INVESTIGATIONS
Eosinophilia not present.
Psychogenic pruritus
SIGNS / SYMPTOMS
Less likely to present with nondermatologic symptoms and signs although there may be no differentiating features.
Strongyloides infection more likely in a person migrating from an endemic area.
INVESTIGATIONS
Eosinophilia not present.
Urticaria
SIGNS / SYMPTOMS
Urticarial lesions resolve within 24 hours.
INVESTIGATIONS
Clinical diagnosis.
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