Uganda announced two more cases of Ebola on Wednesday – confirmation for the first time that the deadly virus had spread beyond the borders of Democratic Republic of Congo.

The Ugandan cases showed the epidemic was entering a “truly frightening” phase and was likely to spread further and kill many more people, one infectious disease specialist told Reuters.

Emergency medical teams and Uganda’s health minister, Jane Ruth Aceng, were travelling to the border area where a five-year-old boy who contracted Ebola died late on Tuesday.

He had just crossed the border from Congo with his family, who were now being monitored in isolation, a Ugandan health official said.

“Two more samples ... have tested positive,” the World Health Organisation said on Twitter, citing the health minister and bringing the total tally of confirmed cases to three.

“This epidemic is in a truly frightening phase and shows no sign of stopping anytime soon,” said Jeremy Farrar, an infectious disease specialist and director of the Wellcome Trust global health charity, which is involved in fighting Ebola.

The men and women on the frontline against Ebola and other hazards Show all 6 1 /6 The men and women on the frontline against Ebola and other hazards The men and women on the frontline against Ebola and other hazards Linda Dixon, 60, leads research into African swine fever at the Pirbright Institute in Surrey "For more than 25 years I've been trying to develop a vaccine for the African swine fever virus, which causes death in domestic pigs, and has symptoms quite like Ebola. It came from East Africa in the 1920s and was transmitted to Georgia in 2007 via food from shipping that was fed to pigs. It has now spread to neighbouring countries and this year entered the EU via Poland, Lithuania, Latvia and Estonia. It's difficult to eliminate because it also infects wild boar, which populate large parts of Europe." David Vintiner The men and women on the frontline against Ebola and other hazards Simon Woodmore, 45, is a paramedic and operations officer for London Ambulance Service's Hazardous Area Response Team (Hart) "I have a helmet for all occasions – five in all – as well as an array of outfits, including breathing apparatus and gas-tight suits, respirators and chemical protective suits. My job is to put paramedics where historically they could not have worked. We were born out of the Tokyo subway sarin attack in 1995, and have been running as Hart since 2006. There are 94 of us in London dealing with chemical, biological and radiological incidents, as well as building collapses and floods." David Vintiner The men and women on the frontline against Ebola and other hazards Simon Woodmore, paramedic and operations officer "We've always dealt with contagious diseases and work with the Royal Free Hospital London high-level isolation unit to transfer confirmed cases, which fortunately is rare. A lot of it is communicating with the patient in a caring and compassionate way, which can be difficult when you're in full gear. There is an increased awareness of Ebola, but it's about reinforcing the processes we already have in place. Any personal risk is mitigated by our training and equipment." David Vintiner The men and women on the frontline against Ebola and other hazards Benjamin Black, 33, is a specialist registrar in obstetrics and gynaecology for Médecins Sans Frontières (MSF) "In June I travelled to Sierra Leone, where one in 21 women of reproductive age dies in childbirth. This was my first mission, and the reason I got into medicine. I had my eyes wide open to Ebola; though it was still in its early days and concentrated across the border in Guinea, within days I had my first suspected Ebola cases in maternity. It was happening." David Vintiner The men and women on the frontline against Ebola and other hazards Benjamin Black, Médecins Sans Frontières "You need a healthy amount of fear to be safe, as well as protocol and organisational back-up. The greatest fear then is how long you can keep getting it right. There is also a huge psychological element. I checked my temperature daily, but in a hot, humid country there's a constant feverish feeling anyway. We had scares and one of our national nurses was infected, probably in the community. He sadly died and it had a huge impact on the team." David Vintiner The men and women on the frontline against Ebola and other hazards Lisa Jameson, 29, is a National Institute for Health Research doctoral research fellow for Public Health England, based at the Porton Down facility in Wiltshire. She specialises in emerging viruses "I was in the field watching patients come into the isolation centre next to us, often with their families. Sometimes they'd be walking and talkative, then die that night. It was tough but we were so busy, and being there made it feel like we were making a difference. When I got home after a month, I felt a sense of guilt that I was able to walk away. I'll almost certainly be going back." David Vintiner

“We can expect and should plan for more cases in DRC and neighbouring countries,” he said, adding: “There are now more deaths than any other Ebola outbreak in history, bar the West Africa Epidemic of 2013-16, and there can be no doubt that the situation could escalate towards those terrible levels.”

The current Ebola epidemic began in August last year in eastern Congo and has already infected at least 2,062 people, killing 1,390 of them.

The viral disease spreads through contact with bodily fluids, causing haemorrhagic fever with severe vomiting, diarrhoea and bleeding.

This outbreak is the second largest on record after a West Africa epidemic in 2013-2016 infected 28,000 people and killed 11,300, mostly in Liberia, Guinea and Sierra Leone.

Uganda’s health minister was travelling to the Ugandan border town of Kasese where the boy had been treated, a health ministry spokesman said.

Kasese lies at the site of a copper mine in the foothills of the ice-capped Rwenzori mountains and traders frequently cross over into Congo.

Experts noted that Uganda, which has been on high alert for possible spread of Ebola and has already vaccinated many frontline health workers, is relatively well-prepared and should be able to limit the virus’s spread.

“The current cases in Uganda will be quickly contained but the failure to stop the current Ebola epidemic in DRC is simply tragic,” said Ian Jones, a professor virology at the University of Reading.