Two missionaries struck down in the African Ebola outbreak may have been saved by a “miraculous” experimental treatment, according to reports.

American aid workers Dr Kent Brantly and Nancy Writebol fell ill at the end of last month after they both became infected with the potentially lethal illness.

The pair, who were working for aid agency Samaritan’s Purse, are believed to have contracted Ebola from another health care worker at the hospital where they worked in Liberia.

But they may have been saved by previously untested treatment, ZMapp, after US authorities short-circuited safeguards for drugs that have not undergone human testing, CNN has reported.

Medics hailed the patients’ dramatic recoveries after emergency vials of the previously top-secret serum were flown to Liberia by the US National Institute of Health (NIH).

Dr Bradley, who went to Africa to treat victims of Ebola, woke up feeling feverish on July 22.

Fearing the worst, he immediately isolated himself but Ms Writebol’s symptoms flared up three days later.

Rapid field blood tests confirmed the infection in both aid workers after they were hit with fever, vomiting and diarrhoea.

The NIH then contacted Samaritan’s Purse and offered the experimental treatment, according to a CNN source.

While scientists believe treatments and a vaccine can be developed for Ebola, there is currently no cure.

ZMapp was developed by biotech firm, Mapp Biopharmaceutical Inc.

It has not been approved for human use, and has not even gone through the proper clinical trial process used to prove the safety and effectiveness of medication.

Dr Brantly and Ms Writebol were reportedly told that the treatment had never been tried before on humans but that it had shown promise in small experiments with monkeys.

They were aware of the risks and “informed consent” had to be obtained from them, according to the report.

The ZMapp vials reached the hospital in Liberia where Dr Brantly and Ms Writebol were being treated on Thursday morning.

It was expected that it would be eight to 10 hours before the medicine would thaw and be given.

But Dr Brantly’s condition took a dramatic turn for the worst, and the ZMapp had to administer ahead of schedule.

Within an hour, however, his condition drastically improved.

He began breathing easier and the rash over his body faded away, with one of his doctors reportedly describing the turn around as “miraculous”.

By the next morning, he was able to take a shower on his own before getting on a specially designed Gulfstream air ambulance jet to be evacuated to the US.

While Ms Writebol’s response to her first dose was said by medics to be less remarkable, a second, administered on Sunday, reportedly triggered a significant improvement. She thereafter became stable enough to be jetted back to the US.

The ZMapp treatment was developed by mice being exposed to fragments of the Ebola virus, with antibodies generated within their blood being harvested to create the medicine.

It supposedly works by preventing the virus from entering and infecting new cells.

On July 30, the Defence Threat Reduction Agency, an arm of the US military responsible for chemical, biological, radiological, nuclear and high-yield explosive threats, allotted additional funding to MAPP Biopharmaceutical due to “promising results.”

The Ebola virus causes viral hemorrhagic fever, affecting multiple organ systems in the body and often accompanied by bleeding.

Early symptoms include the sudden onset of fever, weakness, muscle pain, headaches and a sore throat.

Later sufferers endure vomiting, diarrhoea, impaired kidney and liver function, as well as internal and external bleeding.

A current outbreak in West Africa, which it is feared could spread internationally, has killed more than 850 people.

•Text courtesy of Daily Express (UK). Photo shows doctors attending to an Ebola patient.