Unsuspected strongyloidiasis in hospitalised elderly patients with and without eosinophilia

The prevalence and associated factors of chronic uncomplicated strongyloidiasis were estimated among 200 consecutive elderly patients (aged ≥ 60 years) admitted to a general hospital in northern Italy. One-hundred patients had a peripheral eosinophil concentration ≥ 500 cells/μL (group A), and 100 were age- and gender-matched controls (group B). Measurements included serum IgG anti-Strongyloides antibody titre by an indirect immunofluorescence assay, combined with faecal culture for Strongyloides stercoralis. Anti-Strongyloides antibodies were detected in 28 patients (at high titre in 11 patients). Seropositivity was significantly more common among group A than among group B patients (OR 4.85). Strong seropositivity for anti-Strongyloides antibodies was associated with farm work (p < 0.001), but not with other patient characteristics or with signs and symptoms of strongyloidiasis. In conclusion, strongyloidiasis was relatively common among elderly in-patients; eosinophilia and a history of farm work were the most useful indications for this diagnosis.