Tropical eosinophilia is a hypersensitivity response to a helminthic parasite, particularly filarial parasite (Wuchereria).
The syndrome is characterised by pulmonary manifestations and peripheral blood eosinophilia of more than 2000/mm3.
Tropical eosinophilia is an allergic reaction to helminthic parasites, particularly filarial worms.
Other parasites implicated are ascaris, toxocara and ankylostoma.
Tropical eosinophilia can present in various forms:
Respiratory form (commonest).
A form with constitutional disturbances.
A form with generalised lymphadenopathy and hepatosplenomegaly.
The common respiratory form may be either acute or chronic.
The acute type presents with high-grade fever, exertional breathlessness and cough with scanty expectoration.
The chronic type presents with vague ill-health, low-grade fever, exertional dyspnoea and cough with scanty expectoration.
Physical signs include bilateral rhonchi and crepitations, particularly basal.
Total leucocyte count is raised.
Peripheral blood eosinophilia of more than 2000/mm3.
Raised serum IgE levels.
Sputum examination shows clumps of eosinophils and Charcot-Leyden crystals. Chest radiograph shows bilateral, diffuse, fine mottling in many patients.
Pulmonary function tests show restrictive and obstructive ventilatory defects.
Diethylcarbamazine 6 mg/kg/day in divided doses for 3 weeks.
Long-standing and resistant cases are treated with prednisolone and bronchodilators.