An eosinophilia may be most useful as a guide, but it occurs in some patients without any explainable cause. It also occurs with bronchitis or asthma.
In patients suffering from ankylostomum duodenale, Boycott and Haldane found the average eosinophil count to be 23 per cent. in 16 cases. In another series of 46 cases the eosinophils were only under 7 per cent. in 4 cases and over 20 per cent. in 19 cases. Ashford, from 77 cases in Porto Rico, says that the highest eosinophil count occurs in recent cases. He also says that a rise of eosinophils in chronic cases after treatment favours the prognosis, but that a fall without improvement in the other clinical symptoms may even be suggestive of death. In every case of anæmia with eosinophilia the ova of ankylostomum duodenale should be searched for. Sandwith says that out of 200 cases of this disease in Egypt 78 per cent. had a red blood corpuscle count of under 3,000,000, whilst 28 per cent. of these were under 2,000,000, and so the severity of the anæmia in persons who for the most part work out of doors is very suggestive. The whites usually varied between 10,000 and 13,000.
In filariasis we find a maximal normal, or increased eosinophil count. The average
