Scientists declare Ebola drug Zmapp is 100% effective at treating monkeys with the deadly disease.

All 18 rhesus macaques treated with the drug made 'complete recovery'

            Animals were cured even when given the drug five days after infection 

Monkeys not given the experimental drug quickly fell seriously ill and died

ZMapp is blend of three lab-made antibodies designed to neutralise the virus

Two U.S. doctors given the drug after contracting Ebola later recovered 

Experts warned today the disease is mutating rapidly 

Hopes of a breakthrough in the fight against Ebola have been raised by the 100 per cent successful treatment of monkeys with the deadly disease.

The experimental drug ZMapp cured the animals even when administered five days after infection, while they were displaying severe symptoms.

All 18 rhesus macaques made a complete recovery, in contrast to three other untreated monkeys that quickly fell seriously ill and died.

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Nicotiana benthamiana, the plant from which ZMapp is derived. New research shows the experimental drug ZMapp cured the monkeys even when administered five days after infection

ZMapp is a blend of three laboratory-made antibodies designed to neutralise the virus.

Two U.S. doctors given the drug after they were infected with Ebola while working in Liberia subsequently recovered.

But it is not known whether they were saved by the drug or just lucky. About 45 per cent of those infected in the current outbreak have survived without treatment.

At least two other patients treated with ZMapp have died, possibly because help got to them too late.

The new research, published in a special report on Nature journal's website, provides hard evidence that the drug works and can be highly effective.

A team of scientists led by Dr Gary Kobinger, from the Public Health Agency of Canada, wrote: 'ZMapp exceeds the efficacy of any other therapeutics described so far, and results warrant further development of this cocktail for clinical use ...

'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 news follows a warning from the World Health Organisation (WHO) that the Ebola outbreak in West Africa could eventually claim more than 20,000 victims.

Latest figures show 1,552 deaths from the 3,069 cases reported so far.

A Liberian health worker spraying disinfectant outside a house before entering and removing the body of a man believed to have died from the Ebola virus in Monrovia. Latest figures show 1,552 deaths from the 3,069 cases reported so far

ZMapp is being used to treat William Pooley (left) the first Briton to contract the virus while working as a nurse at a remote health centre in Sierra Leone and (right) Dr Abraham Borbor, was being treated with ZMapp but lost his battle with Ebola this week. He was the deputy chief medical doctor at the country's largest hospital

Ebola, belonging to the family of 'filoviruses', ranks alongside Marburg virus as one of the world's deadliest infections. 

Fatality rates in previous outbreaks have been as high as 90 per cent. 

It kills by overwhelming the immune system and sending the body into shock as blood pressure drops to dangerous levels.

Currently there are is no approved vaccine or post-exposure treatment. Management of the Ebola outbreak in Africa has been confined to palliative care and physical attempts to prevent transmission.

The development of ZMapp and its success in treating advanced stages of Ebola infection was described as a 'monumental achievement' by Professor Thomas Geisbert, from the University of Texas, writing in Nature.

He added: 'The next crucial step will be to formally assess its safety and effectiveness. Testing the latter is clearly difficult, because intentional infection of human subjects in clinical trials is not possible.'

EBOLA VIRUS IS  'MUTATING RAPIDLY,' EXPERTS WARN

Researchers claim the Ebola virus disease (EVD) is rapidly and continually mutating, making it harder to diagnose and treat.

A study of the initial patients diagnosed with the virus in Sierra Leone revealed almost 400 genetic modifications.

And it could be detrimental not only to current treatments, but also to future vaccines that are in the works.

The team of researchers, led by the Broad Institute in Massachusetts and Harvard University, analysed more than 99 Ebola virus genomes.

These were collected from 78 patients diagnosed with Ebola in Sierra Leona in the first 24 days of the outbreak.

Their findings, reported in the journal Science, could have important implications for rapid field diagnostic tests.

The team found more than 300 genetic changes that make the 2014 Ebola virus genomes distinct from the viral genomes tied to previous Ebola outbreaks.

They also found variations in the genome sequence indicating that, from the samples analysed, the outbreak started from a single introduction into humans, subsequently spreading from person to person over many months. 

The treated monkeys were exposed to a lethal level of Ebola virus before receiving three doses of ZMapp starting three, four and five days after infection.

The treatment reversed Ebola symptoms including excessive bleeding, rashes, and liver damage.

Three weeks after they were infected, no trace of the virus could be detected in the animals' blood.

Untreated monkeys all succumbed to the virus by day eight after infection.

One drawback of the research was that it used a version of the virus different from the Guinea strain responsible for the current outbreak, which was not available at the time.

But the scientists went on to show that ZMapp blocks replication of the Guinea strain in laboratory tests.

Dr Alain Kohl, from the Medical Research Council/University of Glasgow Centre for Virus Research, said: 'What needs to be done next is assess against how many strains and species of the virus it can act. 

Clinical trials in humans are not possible so some questions will go unanswered. At present too few people have received the drug to allow conclusions about efficacy and treatment timings, though in emergency situations it is at least one potentially useful option.'

David Evans, Professor of Virology at the University of Warwick, said: 'All animals survived and had undetectable viral loads 21 days post-infection. This is an extremely encouraging result for a virus which has an incubation period of two to 21 days in humans and for which no vaccine exists.

'These results do not prove that the healthcare workers who received ZMapp and recovered did so due to the therapy. Others who also received ZMapp succumbed to the virus.

'Distinguishing between correlation and causation will require analysis of the clinical data on viral loads before and after therapy was administered. Nevertheless, the results are encouraging.'

Professor Martin Hibberd, from the London School of Hygiene & Tropical Medicine, said: 'This looks to be a very well designed study with better than expected results, which give great hope for future clinical trials.

'I hope the team can receive sufficient funding to undertake these clinical trials straight away as this is by far the most advanced potential treatment option available to my knowledge.' 

ARE YOU AT RISK OF CATCHING THE INCURABLE, DEADLY DISEASE

What is Ebola virus disease?

Ebola is a severe, often fatal illness, with a death rate of up to 90 per cent.The illness affects humans as well as primates, including monkeys, gorillas and chimpanzees.

How do people become infected with the virus?

Ebola is transmitted through close contact with the blood, secretions, organs or other bodily fluids of infected animals.

In Africa infection in humans has happened as a result of contact with chimpanzees, gorillas, fruit bats, monkeys, forest antelope and porcupines found ill or dead in the rainforest.

Once a person becomes infected, the virus can spread through contact with a sufferer's blood, urine, saliva, stools and semen. A person can also become infected if broken skin comes into contact with a victim's soiled clothing, bed linen or used needles.

Men who have recovered from the disease, can still spread the virus to their partner through their semen for seven weeks after recovery.

Who is most at risk?

Those at risk during an outbreak include:

·         health workers

·         family members or others in close contact with infected people

·         mourners with direct contact with the bodies of deceased victims

·         hunters in contact with dead animals

What are the typical signs and symptoms?

Sudden onset of fever, intense weakness, muscle pain, headache and sore throat. That is followed by vomiting, diarrhoea, rash, impaired kidney and liver function and internal and external bleeding.

The incubation period is between two and 21 days. A person will become contagious once they start to show symptoms.

When should you seek medical care?

If a person is in an area affected by the outbreak, or has been in contact with a person known or suspected to have Ebola, they should seek medical help immediately.