Filarial tropical pulmonary eosinophilia: a condition masquerading asthma, a series of 12 cases

Abstract

Introduction: Tropical pulmonary eosinophilia (TPE) is a form of occult filariasis, clinically characterized by paroxysmal cough, wheezing and dyspnea which is often misdiagnosed and treated as asthma. These manifestations result from a host immune response to trapped antigens of the microfilarial parasites Wuchereria bancrofti or Brugia malayi in the pulmonary microcirculation.

Case study: We describe three rare presentations of TPE (cor pumonale, cystic lung disease and respiratory distress mimicking acute severe asthma) in our series of 12 cases. All cases were from filaria endemic areas and presented with cough, wheezing and dyspnea, either alone or in combination. Subsequent work-up revealed peripheral eosinophilia, raised serum IgE levels and positive serum filarial antibody and/or antigen in all the cases.

Results: All patients were treated with diethylcarbamazine (DEC), while few required inhaled/systemic corticosteroid. Prompt improvement in clinical symptoms with a decrease in eosinophil count was seen in all. Two cases relapsed requiring a second course of DEC. Long-term outcome was good, however, there was a persistence of restrictive lung function and echocardiographic feature of pulmonary hypertension in the patients with cystic lung disease and cor pulmonale, respectively.

Conclusion: TPE should always be considered in patients from filaria endemic areas presenting with cough, dyspnea or wheezing. High eosinophil count (>3 × 10⁹ cells) with raised IgE level (>1000 IU/mL) in such cases should alert the physician to look for TPE. Early diagnosis and treatment can prevent disease progression and complications.

Keywords: Tropical pulmonary eosinophilia; asthma; cor pulmonale; cystic lung disease; reticulonodular shadows.