Tropical pulmonary eosinophilia in an Orissa village

Tropical pulmonary eosinophilia is usually seen in areas endemic for filariasis. It affects only a small proportion of the population at risk and microfilaria are rarely demonstrated in the peripheral blood. The actual prevalence of the tropical pulmonary eosinophilia syndrome has not been previously studied in an area endemic for filariasis.

We screened the population of a village in the Puri district of Orissa, where filarial infection is endemic, to determine the prevalence of tropical pulmonary eosinophilia by clinical examination measuring the absolute eosinophil counts, performing a chest X-ray and examining the stools for the presence of the parasite. Sera from symptomatic cases who had an eosinophil count above 2000 per cmm were further tested for filarial specific IgG and total IgE and the results compared with control sera obtained from 15 age- and sex-matched normal individuals.

We were able to screen 1754 (91%) out of 1918 villagers who were more than 5 years old and found 69 cases who had typical clinical features of tropical pulmonary eosinophilia. Only 6 (0.34%) of these had eosinophil counts above 3000 per cmm and were considered to have the disease. Only 2 of the 6 had associated filarial lesions, one had microfilaraemia and 3 had typical chest X-ray changes. The mean (+/- SD) titres for filaria specific IgG (0.355 +/- 0.315 v. 0.120 +/- 0.092) and total IgE (0.455 +/- 0.316 v. 0.114 +/- 0.075) were significantly higher in cases with tropical pulmonary eosinophilia than in control subjects. The level of eosinophilia was related neither to the patients' immune status nor to the severity of the radiological lesions. All cases recovered after therapy with diethylcarbamazine.

Tropical pulmonary eosinophilia is not uncommon in this community in Orissa where filariasis is endemic. However, the syndrome is rarely associated with clinical filarial lesions.