Some people are calling ZMapp the miracle drug for Ebola after it cured the two Americans who contracted the disease while working in West Africa.

It has cured five out of the seven patients to whom it has been given, and as noted in a study published in Nature, has also successfully cured a group of 18 monkeys who were infected with the Ebola virus.

Doctors are optimistic, but maintain a healthy sense of caution when acknowledging the drug's efficacy.

ZMapp, created by Mapp Biopharmaceuticals in San Diego, is still an experimental drug. The doses used on humans were given under "compassionate use" guidelines.

Aid workers Dr. Kent Brantly and Nancy Writebol were given the experimental drug after contracting the disease in Liberia. They were both flown to the U.S. for treatment at Emory University Medical Hospital in Atlanta and were released last week, cured of the disease.

However, doctors were slow to credit the drug because they felt a number of other factors such as the higher level of care received in the U.S. or the blood transfusion Brantly received from the boy who survived an infection of Ebola.

Now, scientists have more convincing evidence of ZMapp's efficacy. Researchers injected a group of monkeys with Ebola. They found that the drug could be given up until five days after infection and still be effective in curing the monkeys. The three monkeys who did not receive the drug died after eight days.

This is hopeful for those fighting Ebola, which has been fatal to more than half of the 3,069 people who have been infected with the virus. However, Ebola is spreading. Senegal confirmed its first case Friday

Additionally, the strain of Ebola given to the monkeys is not the same strain that is going through West Africa, but scientists think that it will still be effective.

"It's very, very hard for me to believe that this would not have substantial utility in treating human disease," said Thomas Geisbert, a professor at the University of Texas Medical Branch in Galveston, who reviewed the study for Nature.

According to Mapp Biopharmaceutical, however, its current supply of the drug has been exhausted and it takes months to create. Researchers also think that, at most, the company could produce 20 to 40 doses a month working at full speed.

However, since scientists do not know the appropriate dose size or dose frequency, it is hard to get firm numbers as to how many people will be able to benefit.

Regardless, it will be months before the drug is available for human use. Until then, health officials suggest that the best way to control the outbreak is how they have been approaching it: identifying and diagnosing patients with the disease, isolating them, tracing the people they have been in contact with, testing those people and continuing until all patients who could have possibly been exposed have been isolated.