Under the emergency use designation, certain laboratories in the United States and other countries have been authorised to use the test for a limited period to detect the type of Ebola that has been spreading in West Africa.

London - Fears are growing that the most lethal form of the Ebola virus can mutate into an airborne pathogen, making the spread of the terrifying disease more difficult to check.

It was previously thought that the untreatable virus, which causes massive internal bleeding and multiple organ failure, could be transmitted only through contact with infected blood.

But now Canadian researchers have carried out experiments showing how monkeys can catch the deadly disease from infected pigs without coming into direct contact.

“Our findings support the hypothesis that airborne transmission may contribute to spread, specifically from pigs to primates, and may need to be considered in assessing transmission from animals to humans in general,” they said.

The findings come as scores of people in Uganda were isolated last week to prevent the spread of a new Ebola outbreak that has already killed three in the country.

Ebola causes fatal haemorrhagic fevers in humans and many other species of non-human primates. It was first reported in 1976 in Congo and is named for the river where it was recognised. There is no cure or vaccine.

The illness is characterised by fever, headache, joint and muscle aches, sore throat and weakness, followed by diarrhoea, vomiting, and stomach pain, according to the US-based Centres for Disease Control and Prevention.

“A rash, red eyes, hiccups and internal and external bleeding may be seen in some patients.”

The virus is known to be transmitted through direct contact with the blood or secretions of an infected person, or objects that have been contaminated with infected secretions.

It is often spread during funerals where there has been an outbreak when the bereaved come into contact with an Ebola victim.

In some cases, it can trigger organ failure and unstoppable bleeding, killing a previously healthy adult within days.

One of the deadliest diseases known, it has killed two-thirds of the roughly 1 850 people who have been diagnosed with it.

Experts say this extreme virulence is its weak spot.

The virus can be contained because it kills its victims faster than it can spread to new ones.

However, if the disease is now airborne it could make containment more difficult.

Researchers at the University of Manitoba in Winnipeg deliberately infected six piglets with the Ebola virus and put them in pens where macaque monkeys were housed in wire cages.

Within eight days all four monkeys had caught the virus through indirect contact, according to the study published in the journal Scientific Reports.

Dr Gary Kobinger from the National Microbiology Laboratory at the Public Health Agency of Canada took part in the study.

He told BBC News that they suspect that large droplets of moisture containing the virus were being exhaled with the piglets’ breath.

“They can stay in the air, but not long, they don’t go far,” he said. “But they can be absorbed in the airway and this is how the infection starts, and this is what we think, because we saw a lot of evidence in the lungs of the non-human primates that the virus got in that way.”

Further work is needed, but the findings are worrying as macaques are close genetic relatives to humans, said the researchers.

Fruit bats are a known “reservoir” for the Ebola virus, and people have also contracted the disease after handling infected chimps, gorillas, monkeys, forest antelope and porcupines.

But this research suggests that wild or domestic pigs could also be a natural host.

The latest outbreak of the disease in Uganda – in a district just 65km from the capital Kampala – comes roughly a month after the country declared itself Ebola-free following an earlier outbreak in a remote district of western Uganda.

The latest Ebola outbreak, officials say, is of the Sudan strain of Ebola and not linked to the previous one, of the Congo variety, which killed at least 16 villagers in July and August in the western district of Kibaale.

In addition to the three dead in the latest outbreak, up to 15 are being monitored for signs of the disease, officials said.

Ebola is especially feared in Uganda, where multiple outbreaks have occurred over the years, and news of it can cause patients to flee hospitals to avoid infection.

In 2000, in one of the world’s worst Ebola outbreaks, the disease infected 425 Ugandans and killed more than half of them in the country’s north. Another outbreak in 2007 killed 37 people in Bundibugyo, a remote district near the Congolese border.

– Daily Mail