35 of the 40 cases with Isospora belli infection were from France: 33 patients presenting with "travellers diarrhoea" were infected abroad (especially in tropical Africa and the Middle East) but 7 were infected in France itself. Charcot-Leyden crystals were found together with I. belli oocysts in the stools of 35 subjects. 61% of the cases presented with hypereosinophilia of between 6 and 20%. The average eosinophilia was 7.6% or 649/mm3.