Abstract We report a case of hypereosinophilia syndrome (HES) due to Wuchereria bancrofti infection presenting with a deep venous thrombosis in a previously healthy adult male. The patient presented with a 3-mo history of low-grade intermittent fever and an acute onset of swelling of the left lower limb. Laboratory investigations revealed marked eosinophilia with a peak absolute eosinophil count of 8194 cells/µl and ultrasound evidence of extensive left iliofemoro-popliteal thrombosis. Our workup for secondary causes confirmed W. bancrofti antigen positivity, following which antiparasitic therapy was promptly initiated and a reduction in eosinophil count was noted. Our case highlights the importance of recognition of filariasis as a cause of reactive HES in an endemic region and recognising the thromboembolic complications that may arise from it.
Pai et al. (2026) studied this question.