The outbreak was traced to infected vervet monkeys cut up in the labs for polio research;they came from close to the present outbreak in Uganda.

• 这种病毒的出现可追溯到感染疾病的黑长尾猴，当时这些猴子在实验室已经被肢解以进行小儿麻痹症的研究，而这些猴子所感染的疾病与乌干达出现的疾病十分相似。