removing them from the usually very limited fly area to some neighbouring fly-free spot. Movements of infected individuals towards hitherto uninfected countries must necessarily be attended with great risk of the introduction of the disease. Whether such movements can be prevented in savage lands depends greatly on local circumstances. Wherever possible they should be prevented. Dutton and Todd suggest that an easily ascertained condition, more or less general in trypanosomiasis, namely, enlargement of the cervical glands, should be employed in eliminating dangerous individuals. Many years ago slave-dealers adopted such a method to shield themselves from loss. As a rough test it has some value. But in some cases of trypanosomiasis the glands are not appreciably enlarged at all times. Moreover, as they are often enlarged in other conditions, an injustice might be done in enforcing such a measure.
Hodges and his colleagues in Uganda inform us that the fly ground proper is always a very narrow strip indeed, not more than ten to fifteen yards, and always along the water's edge; and that the insects very rarely extend their feeding beat beyond sixty yards of this, whether on the land side or on the water side. It is true they may follow with great persistency a man who has just passed through this narrow belt, for several hundred yards, rarely as far as half a mile; but it is obvious that if the ten or fifteen yards at the water's edge be made unsuitable for the fly, as can readily be done by clearing it of jungle, there will soon be no flies to follow, and the place will become safe. Therefore, where feasible, fly spots, where there are landing-places, ferries, wells, or roads, should either be avoided altogether or be cleared of jungle for some yards—— to be safe, thirty——from the water's edge. This is a practical measure of proved value in Uganda.* [1]
- ↑ * Duke has tried the injection of prophylactic doses of arseno-phenylglycin in the monkey and subsequent development of the trypanosome in the tse-tse fly. He finds that a monkey thus injected cannot be subsequently infected by a positive fly, and that the development of the trypanosome in the tse-tse fly is inhibited by imbibing drug -containing blood.
