The rapid spread of "super malaria" in South East Asia is an alarming global threat, scientists are warning.
This dangerous form of the malaria parasite cannot be killed with the main anti-malaria drugs.
It emerged in Cambodia but has since spread through parts of Thailand, Laos and has arrived in southern Vietnam.
The team at the Oxford Tropical Medicine Research Unit in Bangkok said there was a real danger of malaria becoming untreatable.
Prof Arjen Dondorp, the head of the unit, told the BBC News website:"We think it is a serious threat.
"It is alarming that this strain is spreading so quickly through the whole region and we fear it can spread further [and eventually] jump to Africa."
About 212 million people are infected with malaria each year.It is caused by a parasite that is spread by blood-sucking mosquitoes and is a major killer of children.
The first choice treatment for malaria is artemisinin in combination with piperaquine.
But as artemisinin has become less effective, the parasite has now evolved to resist piperaquine too.
There have now been "alarming rates of failure", the letter says.
Prof Dondorp said the treatment was failing around a third of the time in Vietnam while in some regions of Cambodia the failure rate was closer to 60%.
Resistance to the drugs would be catastrophic in Africa, where 92% of all malaria cases happen.
'Against the clock'
There is a push to eliminate malaria in the Greater Mekong sub-region before it is too late.
Prof Dondorp added:"It's a race against the clock - we have to eliminate it before malaria becomes untreatable again and we see a lot of deaths.
"If I'm honest, I'm quite worried."
Michael Chew, from the Wellcome Trust medical research charity, said:"The spread of this malaria 'superbug' strain, resistant to the most effective drug we have, is alarming and has major implications for public health globally.
"Around 700,000 people a year die from drug-resistant infections, including malaria.
"If nothing is done, this could increase to millions of people every year by 2050."
The number of NHS mental health staff who have had to take sick leave because of their own mental health issues has risen by 22% in the past five years.
Those taking long-term leave of a month or more rose from 7,580 in 2012-13 to 9,285 in 2016-17, BBC freedom of information requests found.
The union Unite said cuts to staff and services were putting extra pressure on front-line mental health workers.
The Department of Health said it was transforming mental health care.
Out of 81 mental health authorities in England, Scotland, Wales and Northern Ireland, 58 provided the BBC with comparable information.
Looking after ourselves
One mental health doctor who had to take mental health leave told 5 live anonymously:"I don't think I realised it was happening until quite a long way down the road."
She explained that she was getting irritable with her partner, her sleep was disturbed and she couldn't switch off from work.
"In the end, I went to my GP who offered me a sick note.I was quite taken aback that it was quite so obvious to my GP that I needed to be off work." she said.
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"As mental health practitioners, we are pretty rubbish at putting our own mental health first.You need to put your own oxygen mask on first before putting it on to someone else."
5 live also spoke to a group of community mental health nurses at the Leeds and York Partnership NHS Foundation Trust about how they cope with the pressure of the role.
"I think when you're so passionate about something it's very easy to overlook just how much you are taking on," said Kate Ward, an occupational therapist working as a care co-ordinator in the team.
She said it was important for staff to understand what their thresholds are, recognising the early signs of their resilience getting chipped away.
"We think we are this person that can help everybody, but we have to remember that we have to help ourselves sometimes," Julie Poole, a community mental health nurse, explained.Image caption
Dave Munday, mental health professional lead at union Unite, which represents 100,000 health workers across the UK, said:"These figures are of real concern and they only tell part of the story.
"We know that many more mental health professionals will feel unwell but try to 'soldier on' or mask the real reason they're taking leave.
"Our members tell us workplace stress is increasing and that cuts to staff and services mean they're working longer hours with fewer resources.
"Staff themselves are feeling the impact of austerity and there's a lack of trust in the often repeated but not fulfilled promises of the current government."
Not good enough
A spokesman for the Royal College of Nursing said:"Mental health staff face unique challenges.The pressure to make the right decision and provide care for extremely vulnerable people against a backdrop of staff shortages, can take its toll on their health and wellbeing.
"More than 40,000 mental health staff are assaulted every year, and too often violence is seen as 'part of the job' by employers, and the authorities.
"This isn't good enough.We want to see action on work-related stress, including violence at work which, as well as physical injuries, adds to burnout stress, and depression."
The Department of Health said:"We are transforming mental health care for everyone in this country, including NHS employees, with record amounts of investment.
"There is more to do - that is why we are undertaking one of the largest expansions of mental health services in Europe, so that all staff have the time to look after themselves as well as others."
One of Europe's leading heart and lung hospitals - Papworth - has been granted a royal title by the Queen.
The hospital near Cambridge, which carried out heart surgery on the Duke of Edinburgh in 2011, will become Royal Papworth Hospital.
Its name officially changes in 2018.
Next year marks the 100th anniversary of the hospital, which opened as a tuberculosis colony in the small Cambridgeshire village of Papworth Everard in 1918.Image copyright Cambridgeshire Archives Image caption Image copyright Cambridgeshire Archives Image caption
Since then the hospital has become renowned for its pioneering cardiothoracic procedures, treating more than 100,000 patients from across the UK each year.
In 2015 its surgeons were the first in Europe to successfully perform a heart transplant using a non-beating heart.
More than 30 such operations have been carried out since then, increasing its transplant rate by more than one third.Image copyright Cambridgeshire Archives Image caption Image copyright Papworth Hospital NHS Foundation Trust Image caption
The title will make Papworth the first "royal" hospital in the east of England, a spokesman said.
It has been bestowed "in recognition of its pioneering history and continued commitment to developing the treatments of the future", he added.
Prof John Wallwork, chairman of Papworth Hospital NHS Foundation Trust, and the surgeon who jointly performed the first heart, lung and liver transplant, said he was "thrilled to see the hospital get this recognition from the Queen".
The hospital is to move to Cambridge Biomedical Campus - the site which houses Addenbrooke's Hospital - next year.Image copyright Papworth Hospital Image caption
The £165m 310-bed new hospital will replace the current 276-bed facility.
It is not yet known what will happen to the old hospital site....
Scientists have engineered an antibody that attacks 99% of HIV strains and can prevent infection in primates.
It is built to attack three critical parts of the virus - making it harder for HIV to resist its effects.
The work is a collaboration between the US National Institutes of Health and the pharmaceutical company Sanofi.
The International Aids Society said it was an "exciting breakthrough".Human trials will start in 2018 to see if it can prevent or treat infection.
Our bodies struggle to fight HIV because of the virus' incredible ability to mutate and change its appearance.
So the immune system finds itself in a fight against an insurmountable number of strains of HIV.
But after years of infection, a small number of patients develop powerful weapons called "broadly neutralising antibodies" that attack something fundamental to HIV and can kill large swathes of HIV strains.
Researchers have been trying to use broadly neutralising antibodies as a way to treat HIV, or prevent infection in the first place.
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Dr Gary Nabel, the chief scientific officer at Sanofi and one of the report authors, told the BBC News website:"They are more potent and have greater breadth than any single naturally occurring antibody that's been discovered."
The best naturally occurring antibodies will target 90% of HIV strains.
"We're getting 99% coverage, and getting coverage at very low concentrations of the antibody," said Dr Nabel.
Experiments on 24 monkeys showed none of those given the tri-specific antibody developed an infection when they were later injected with the virus.
Dr Nabel said:"It was quite an impressive degree of protection."
The work included scientists at Harvard Medical School, The Scripps Research Institute, and the Massachusetts Institute of Technology.
Clinical trials to test the antibody in people will start next year.
Prof Linda-Gail Bekker, the president of the International Aids Society, told the BBC:"This paper reports an exciting breakthrough.
"These super-engineered antibodies seem to go beyond the natural and could have more applications than we have imagined to date.
"It's early days yet, and as a scientist I look forward to seeing the first trials get off the ground in 2018.
"As a doctor in Africa, I feel the urgency to confirm these findings in humans as soon as possible."
Dr Anthony Fauci, the director of the US National Institute of Allergy and Infectious Diseases, said it was an intriguing approach.
He added:"Combinations of antibodies that each bind to a distinct site on HIV may best overcome the defences of the virus in the effort to achieve effective antibody-based treatment and prevention."