US official advice against non-essential travel to Rwanda in light of the outbreak of the deadly Marburg virus is “not fair”, Africa’s top health official Jean Kaseya has said.

The head of the Africa Centres for Disease Control and Prevention (Africa CDC) added that it was “not the treatment Rwanda and Africa deserve”.

In just two weeks, Rwanda has recorded 13 deaths from the disease - most of them among healthcare workers, according to a statement from the country’s health minister.

But the outbreak is under control, the authorities say.

Nevertheless, those on the front line of dealing with its consequences remain nervous.

“What scares you the most [is] when you see people of the same profession dying,” said Maria, not her real name, an intensive-care nurse at a hospital in the Rwandan capital, Kigali.

Maria talked to the BBC on condition of anonymity as she was concerned if she spoke out publicly, she would lose her job.

“I can’t stop telling myself that I might be the next, that maybe I am positive but without symptoms yet,” said the 46-year-old nurse and mother.

She told the BBC that several of her colleagues were sick, being treated in isolation, and that more than one had already died as a result of the virus. She described the overwhelming strain faced by staff in the facility every day.

On average half of patients infected with the Marburg virus will die, according to the World Health Organization (WHO). Fruit bats host the virus, and it spreads from human to human through contact with infected bodily fluids such as sweat, urine and blood.

While no vaccines against Marburg have been approved, Rwanda has begun trials with supplies sent from Sabin Institute, a US-based non-profit organisation.

It has vaccinated 200 people, prioritising healthcare workers and contacts of confirmed cases, with plans to expand vaccination as more doses arrive.

Africa CDC has also provided 5,000 Marburg test kits to Rwanda and neighbouring countries to strengthen cross-border surveillance.

Maria has not yet been offered a vaccine but remains determined to continue working.

“I am a nurse, I am on the front line, we have to fight it, but the fear is constant,” she said.

Anxiety over the virus spreading to Europe saw authorities in Germany shut down part of Hamburg’s central station a few days ago, after a medical student and his companion fell ill following their visit to Rwanda. Both eventually tested negative for Marburg virus.

The US Centers for Disease Control and Prevention has issued its second-highest level of travel notice for Rwanda, recommending that people avoid non-essential travel to Rwanda due to the outbreak.

Rwanda's neighbours, Tanzania, Uganda, and the Democratic Republic of Congo, which have all recorded Marburg cases in the past, have all increased their border surveillance to prevent the spread.

While Burundi has gone a step further, setting up an emergency treatment and isolation centre in readiness for an outbreak.

Africa’s CDC said it was improving public health emergency training to help staff handle any Marburg outbreaks more effectively.

The Rwandan authorities have taken steps to restrict funerals for virus victims to 50 attendees to help curb the spread of the disease.

Additionally, they have implemented passenger questionnaires, and hand-sanitising stations at departure points, along with temperature checks at entry and exit points across the country.

Rwanda’s health minister has said the outbreak is focused around a cluster of cases in the capital.

“In different departments you’d find very few staff on shift,” says a second nurse, Claire, who also did not want to be identified. She works at another hospital in Kigali.

“I have lost people I knew; I lost a colleague who was dear to me, at another hospital,” she says.

Rwanda's authorities have said early identification of Marburg cases has been particularly challenging as it initially presents with similar symptoms to malaria which is very common across the region.

Health Minister Sabin Nsanzimana said the country was being extremely cautious and mass testing is under way for anyone with high fever, headache, vomiting, and muscle aches. Hospital visits have been stopped at any facilities where health workers tested positive for the virus.

Marburg virus is closely related to Ebola, which killed over 11,000 people in West Africa from 2014-2016, according to the WHO.

Relying on information learnt from that outbreak, Rwanda, in partnership with the WHO and Africa CDC, said it is responding quickly with strict hygiene measures, public awareness, providing protective gear for health workers, and isolating confirmed cases.

Rwanda has received 5,100 vials of remdesivir, an antiviral drug from Gilead Science used to combat Ebola in the past, to help fight the virus.

While trial vaccinations are ongoing, the second nurse the BBC spoke to is also yet to get a vaccine.

“I hope that things will soon get better… some vaccines have arrived, this is what is giving us some hope” she said.