Western country urged to 'stay vigilant' as mystery new illness kills more than 50 people in just hours of symptoms

Health experts have urged Aussies to be 'vigilant' amid an outbreak of a mystery new illness in the Democratic Republic of the Congo.

Scientists are frantically trying to identify what the illness is following the deaths of more than 50 people, who passed away just hours after their symptoms first arose.

Officials announced 419 infections have been recorded in Congo as of Monday (24 February), which is almost a month after the outbreak is believed to have first began.

It all started on 21 January this year, when three children in the village of Boloko reportedly ate a dead bat.

The youngsters died 48 hours later and had each developed symptoms of 'hemorrhagic fever', which are a group of illnesses caused by several distinct families of viruses.

According to the UK government, some of these can cause 'mild illnesses', however, others can cause 'severe, life-threatening disease; some are high consequence infectious diseases (HCIDs)'.

It states: "The viruses depend on their animal hosts for survival, so they are usually restricted to the geographical area inhabited by those animals.

"The viruses are endemic in areas of Africa, South America and Asia, with some present in parts of Europe."

More than 50 people have passed away from the mystery illness in Congo so far (GLODY MURHABAZI/AFP via Getty Images)

Hemorrhagic fever symptoms are often linked to known deadly viruses, such as Ebola, Marburg and dengue - however, these have been ruled out after testing of more than a dozen samples.

The World Health Organisation (WHO) explained in the latest weekly bulletin that this raises 'concerns about a severe infectious or toxic agent' being the source of the mystery illness.

Dubbing the situation a 'crisis' and warning it poses a 'significant public health threat', the WHO explained sufferers have been experiencing symptoms such as fever, chills, headache, myalgia and body aches.

As well as this, those who have been infected might also have a runny nose, excessive sweating, a cough, neck stiffness vomiting, diarrhoea, and abdominal cramps.

The reason experts are so concerned is that nearly half of the deaths occurred within just 48 hours of the onset of symptoms - something which Serge Ngalebato, medical director of Bikoro Hospital, said was 'really worrying'.

Senior research fellow in global health at the University of Southampton, Dr Michael Head, also warned that the potential of the illness spreading is a 'real concern'.

He told Metro that although a pandemic is 'very unlikely', the world should be wary of the 'possibility' of a 'wider spread around the DRC and across to other countries'.

As a result, health chiefs across the globe are on high alert just in case - including in Australia.

Experts explained plane travel makes it easy for illnesses to spread from country to country (Getty Stock Photo)

Experts such as Catherine Bennett, Professor of Epidemiology at Deakin University, have said that although those Down Under shouldn't panic about the unknown illness right now, it's important to remain cautious.

"I'm not nervous," she told the Daily Mail regarding the current lack of information surrounding the illness. "It's about being vigilant.

"I would expect we'd hear something in the next few days, particularly if it's something that is an existing known pathogen. It's a complex picture but they're ruling things out.

"Sometimes it might be something that's familiar but different enough where the current tests don't work on it. They're also looking at food or water poisoning. It might not be infectious, it might be an environmental source."

In terms of the risk of it spreading, Professor Bennett said experts need to determine 'how long people go from exposure to showing symptoms' and when they become 'infectious'.

"You can be in another country in hours and that might be someone who's unfortunately caught something - not symptomatic yet - on a plane and that's what we're worried about in terms of spread," she added.

Infectious diseases physician and microbiologist Peter Collignon also emphasised that the risk of the illness reaching Australia - or anywhere else for that matter - isn't imminent.

"It's a problem, but there's a low probability it will transmit all around the world," he said. "They should be able to work out what it is in the next few days because they've got enough material."