Tropical eosinophilia, an occult form of filariasis, results from immunolog i c hyperresponsiveness to the human
filarial parasites, Wuchereria bancrofti and Brugia malayi. The clinical syndrome is characterised by cough, dyspnoea,
nocturnal wheezing and chest discomfort and is occasionally accompanied by constitutional symptoms such as weight
loss, anorexia and fever. Chest radiographs show-diffuse reticulo-nodular infiltrates and pulmonary function reveals
restrictive ventilatory defect with mild obstruction. Laboratory studies are characterised by marked peripheral blood
eosinophilia and high serum levels of IgE and filaria-specific IgG and IgE antibodies. The hallmark of the syndrome is
markedly elevated eosinophils in the lower respiratory tract and interstitial lung fibrosis develops if left untreated.
Although patients respond rapidly following a standard 3-week course of diethylcarbamazine, there is incomplete
reversal-of clinical, hematological, radiological, physiological and pathological changes despite treatment. Therefore
other therapeutic modalities such as the addition of corticosteroids to the DEC regimen have to be evaluated in
controlled clinical trials
