Tsetse flies are found just in sub-Saharan Africa though only certain species transmit the disease.
采采蝇仅在南撒哈拉非洲存在，但只有某些种类的采采蝇会传播该病。
2
The disease is mostly transmitted through the bite of an infected tsetse fly but there are other ways in which people are infected with sleeping sickness.
疾病主要通过受感染采采蝇的叮咬传播，但也有其它途径可使人感染昏睡病。
3
The disease, transmitted mainly by tsetse flies, is prevalent in 37 countries among the poorest of the world.