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182 According to Laveran, Roudsky, Kudicke, and Werbitzski, at times the acquired drug resistance is accompanied by a change in the morphology of the trypanosome. In T. bruceithis resistance to parafuchsin and oxazine is accompanied by a disappearance of the blepharoplast, and this feature persists on sub-inoculation in untreated animals (even as far as the 140th sub-inoculation), but is lost immediately the trypanosome is passed through the appropriate definitive host. In the treatment of trypanosomiasis, concurrently with the use of drugs, every effort should be made to keep the patient in good general health. Rest, warmth, and residence in a cool and healthy climate, the systematic use of quinine for any concurrent malarial infection, and the avoidance of fatigue and everything that might depress, should be insisted on.

The idea of cure must not be entertained until the patient has been free from all symptoms for many months, nor until the repeated injection of several cubic centimetres of his blood has failed to induce trypanosomiasis in susceptible animals. Immunisation.—— Attempts have been made to procure a curative and immunizing serum, but, although a certain amount of success has attended these efforts in respect to the lower animals, as regards man they have failed.

Prophylaxis.—— The indications for prophylaxis are based principally on the habits of Glossina palpalis and the existing conditions as regards the presence of the infection in a locality.

In endemic regions the fly areas should be located and avoided. If such regions have to be traversed the journey should be made during dark nights when tse-tse flies do not feed, or with such precautions as are used by the natives for the protection of their cattle in nagana-infected spots. Those who are compelled to live in tse-tse regions should have their houses and persons carefully guarded against the fly. Manifestly it is desirable ——whether it is feasible is another question—— to avoid localities in which the natives are affected, and to prevent the infection of the local tse-tse flies by surrounding people having trypanosomes in their blood with mosquito netting; or by other measures, such as