Experimental medication called ZMapp is effective in treating monkeys, a new study shows.

The test drug cured all 18 lab monkeys, which were infected with the Ebola virus. Surprisingly, the medication was even effective in later stages of the infection.

"It's fantastic news," said study co-author Gary Kobinger of the Public Health Agency of Canada, according to USA Today.

ZMapp is made by Mapp Biopharmaceuticals of San Diego. The drug was earlier given to a handful of Ebola victims on compassionate grounds. Latest research on animals suggests that ZMapp might be effective in treating Ebola infection. The drug is yet to be tested formally on human subjects.

In the current study, 18 rhesus macaques with Ebola infection received the drug. The researchers found that the drug was effective even five days after infection.

The study was conducted by Public Health Agency of Canada.

"The evidence presented here suggests that ZMapp offers the best option of the experimental therapeutics currently in development for treating Ebola infected patients," Kobinger's lab said, according to nbc news. "We hope that initial safety testing in humans will be undertaken soon, preferably within the next few months, to enable the compassionate use of ZMapp as soon as possible."

The current drug - ZMapp - has a mixture of three antibodies, according to Livescience. The drug reduced several characteristic symptoms of Ebola such as bleeding and rash. Three monkeys in the study were not given the drug and acted as a control group. All animals in the control group died within eight days of the infection.

As many as 20,000 people could be affected by the Ebola outbreak in West Africa, The World Health Organization recently said. U.S. government and drugmaker GlaxoSmithKline announced that they are starting first human trials of a vaccine against the deadly Ebola, nbc news reported.

The study is published in the journal Nature.