An experimental Ebola drug healed all 18 monkeys infected with the deadly virus in a study, \_17\_ hopes that the treatment might help fight the outbreak raging through west Africa — once more of it can be made. The monkeys were given the drug, ZMapp, three to five days after they were infected with the virus and when most were showing symptoms. It is not known how well the drug would work in people, who can take up to 21 days to show symptoms and are not infected \_18\_ the lab monkeys were. Several experts said it is not possible to \_19\_ a window of opportunity for treating people, but that it was encouraging that the animals \_20\_ when treated even after advanced disease developed.