Will Pooley was working as a nurse on the Kenema Ebola unit in Sierra Leone, one of the two main clinics in the country working with patients before he contracted the virus. Jo Dunlop, a freelance journalist, met him on several times as she reported on the crisis.

It was a brutal week at Kenema hospital when I met Will six weeks ago. The slowly diminishing nursing staff were reeling in the wake of the death of their respected colleague and friend, Sister Mbalu Fonnie, who became infected with the virus after treating patients on the Ebola ward. Her death closely followed that of seven other nurses who worked on the ward. A few days later, the much-loved Dr Sheik Umar Khan, Sierra Leone's only haemorrhagic fever specialist, would also test positive with the disease.

Will finished his shift late the night we met. It had been a dramatic day involving a riot outside the hospital followed by a walkout by most nurses, which meant that he and his colleague, Sister Nancy Yoko, were left to hold the crumbling fort. They were both exhausted after working 14 hours and at 9pm were forced to make the painful decision to leave the 45 Ebola patients unattended as no one had turned up for the night shift. They both needed a break to gather their strength so they could do it all again the next day. Will was rattled by the dilemma of having to leave the patients alone. "We gave them water and paracetamol and then we had to walk out. Patients are dying the most horrible deaths, I'm expecting to find several corpses tomorrow morning."

Will spoke of the traumatic situations he was confronting each day on the ward. His accounts were unadorned and honest, and he explained some of the practical struggles of dealing with so much death when you have such limited resources. He described patients dying in front of him and then being unable to find help to shift their bodies, which meant leaving bodies lying next to other patients.

He talked about everyday life at the heart of the Ebola outbreak. There were people up, walking and recovering, children playing, sometimes singing and even rare moments of laughter. He described women in recovery, saying: "They were sitting around singing songs, you wouldn't see that on a ward in England, you wouldn't see people singing like that."

Will, who arrived quietly without the backing of an international organisation, spoke of his determination to perform a role that so many simply refused. "I know it's the easiest situation in the world to make a difference, in nursing terms I'm not particularly experienced, or skilled, but in this situation I can really make a difference and make things a lot less bad."

I continued to check in with Will through text messages and a few phone calls. I was worried for his safety and I wanted him to know that he had not been forgotten. He always remained buoyant despite the overwhelming challenges he no doubt faced. There were rumours of the Red Cross turning up to provide more staff and logistical support from Médecins sans Frontières (MSF) but things were moving slowly and nothing concrete had happened a week later. Will still spoke of the lack of staff working night shifts, more nurses getting sick and case numbers continuing to rise.

On my second visit to Kenema two weeks later it seemed that the hospital was turning a corner. Support had arrived at the treatment centre in the form of the MSF and WHO. Patients were being moved into a new ward, there was better sanitation. Staff training and a restructuring of the unit were improving conditions in the hospital for both patients and health workers. Will assured me: "It's a lot safer, it's a lot cleaner environment for the patients and the staff."

Will described how patients who receive a negative test result after recovering from Ebola are showered, given a fresh set of clothes, a certificate declaring they are Ebola-free and a small amount of money for the ride home. Relatives usually gather to meet them and there are emotional outpourings of thanks to the hospital staff and God. It's a beautiful moment for patients and staff that lets at least some light into an otherwise dark situation. "It's great, it's great, seeing them walk away after some of them have been in a terrible state and seeing them on the wards and thinking they're probably going to die. But to see them recover and walk out the door is great."

Will was flanked by a group of upbeat young women who had all been discharged and were keen to take a photograph before they said goodbye. He was clearly popular among the patients and he was fond of them. "They were all together on this one ward," he said pointing to the women, "It will be so quiet in there now."

It was not only the patients who held Nurse William in high esteem but his colleagues as well. Yoko, the tough Sierra Leonean nurse, spent a lot of time on the ward alongside Will. "We have a lot to thank William for, he has motivated us, he has encouraged us." The leader of the hospital, Matron Josephine Sellu, shared a similar sentiment. "William has come here and offered to help in this war against Ebola, we thank him for that. He has taught us things, he has helped our nurses."

Will Pooley's doctors described him as a 'resilient and remarkable young man'. Photograph: Guardian

The last time I saw Will he told me: "At the start, especially, I could feel the weight of the horror that is the inside of the Ebola ward but you quickly get used to it. I don't go on to the ward each morning with that same dread of the corpses and blood that I did to start with. It has become a bit routine now."

The issue of personal safety and that of his colleagues was a concern for Will. But the possibility of becoming infected just did not seem like an option for him. He assured me at one point that "the PPE that we wear protects you against Ebola, full stop really. If you wear it and you don't make any mistakes and everything is done properly then you will never catch Ebola when you are working."

He also said that he did not take the same risks that his colleagues had taken. "I operate very differently to local nurses. A simple example is that it's very normal for staff to eat onsite in a moment of going in and out of the ward. I don't do that. So I'm protected by circumstance in some ways and also I'm a lot more afraid than the local nurses so I take more precautions."

When the small and close community in Freetown heard of Will's positive test result on Saturday it was a devastating blow and cruel reminder of what we all know – those most at risk of catching Ebola are health workers.

Many, like Yoko at the Ebola unit, were shattered by the news but hopeful for the treatment he will receive. "He will be okay, he will receive proper care in England, we will miss him though," she said.

Watching the grainy news footage of Will being taken off an RAF plane inside plastic casing, surrounded by a scrum of medical experts, I wondered what was going through his head. To arrive in one of the poorest countries in Africa and spend two months nursing patients suffering one of the world's deadliest diseases is an extraordinary experience. But to then contract that disease and be transported to the most sophisticated treatment unit on earth is unfathomable.

Will, like so many health workers in Sierra Leone, is a humble hero. His work has saved dozens of lives.

Before I left Kenema I asked Will what he planned to do when he left. "I'll get a motorbike and travel around Sierra Leone. I'll feel great because I know I've earned it."