Eosinophilia in the Tropics: Should Empirical Anthelmintic Treatment Be Considered Standard Practice? A Prospective Cohort Study
Smith Kungwankiattichai, Patsharaporn T. Sarasombath, Pattaraporn Tunsing, Weerapat OwattanapanichABSTRACT
Background
Eosinophilia is a common clinical finding with diverse etiologies. Helminthiasis is a major aetiology in tropical regions, but data from haematology consultation services at tertiary centres in endemic settings are limited.
Objectives
To determine the prevalence of helminthiasis among patients with eosinophilia at a tropical tertiary care centre and identify clinical and laboratory characteristics differentiating helminth from non‐helminth etiologies.
Methods
A prospective cohort study with predefined retrospective outcome classification was conducted at Siriraj Hospital, Thailand (January 2022 to November 2023) in adult patients with blood eosinophilia above 500 cells/μL. All patients underwent helminth screening through stool examination and serological testing for strongyloidiasis, gnathostomiasis, angiostrongyliasis, filariasis and cysticercosis, and received empirical ivermectin or albendazole with monthly follow‐up for 6 months.
Results
Among 131 patients, 76 (58.0%) were diagnosed with helminthiasis, comprising 49 definite (laboratory‐confirmed) and 27 probable (treatment‐response‐defined) infections. Strongyloidiasis (53.1%) was most common among definite infections, followed by gnathostomiasis (40.8%) and cysticercosis (26.5%), with multiple infections in 24.5% of definite cases. The median time to absolute eosinophil count (AEC) normalization was 1.0 month (IQR: 1.0–2.0), with 93.4% normalizing within 3 months. Probable infections were significantly associated with soil contact and forest travel (all p < 0.05), while definite infections were associated with organism‐specific exposures (all p < 0.05). Patients aged 75 years or above showed significantly lower AEC at presentation (adjusted geometric mean ratio 0.52, 95% CI: 0.31–0.89, p = 0.017). Leukopenia and hypoalbuminemia were more prevalent in non‐infectious etiologies.
Conclusions
Helminthiasis was identified in more than half of patients with eosinophilia at a tropical tertiary haematology service. Empirical anthelmintic therapy effectively normalized eosinophilia in the majority within 3 months, supporting its use as a standard initial approach in endemic settings. Detailed exposure anamnesis and concurrent evaluation for non‐helminth etiologies, particularly in patients with leukopenia or hypoalbuminemia, should be routinely performed.