Pauline Cafferkey, the Scottish nurse who was the first person to be diagnosed with the deadly Ebola virus in the UK, is in critical condition.

The Royal Free Hospital said Cafferkey’s health “has gradually deteriorated over the past two days.”

The latest outbreak of Ebola, which began a year ago, is the largest on record. So far, more than 7,800 people have been killed by the virus. Almost all of these have been in West Africa. The latest figures from the World Health Organization estimate that the number of people infected by the disease in Sierra Leone, Liberia and Guinea has now passed 20,000.

Cafferkey had flown to Sierra Leone on November 23 to work as a volunteer nurse at the Kerry Town Ebola Centre. The centre is in a clearing in the Sierra Leonean forest, about an hour’s drive from the capital, Freetown. It is run by the UK-based charity, Save the Children.

After completing her period of voluntary service at the centre, she flew back to Scotland. Her journey involved a flight from Freetown to Casablanca in Morocco, followed by a flight to Heathrow, with a final leg to Glasgow airport—arriving there late evening on December 28. As Cafferkey was returning from a country with an Ebola outbreak, she was screened for the disease at Heathrow and was allowed to fly home to Scotland.

Within hours, she had developed a fever and was admitted to Gartnavel teaching hospital in the west of Glasgow on the morning of Monday, December 29. She was put in an isolation ward and diagnosed as having the Ebola virus.

On December 30, Cafferkey was flown in a special quarantine tent, accompanied by health workers, in a Hercules transport plane to the RAF Northolt airbase in North West London. From there, she was taken in a special ambulance to the high-level isolation unit at the Hampstead Royal Free Hospital. It is the only specialist high-level isolation unit in Europe, and Cafferkey would have entered it via a special entrance. She was treated by health staff wearing protective clothing on a special bed within a quarantine tent.

The UK nurse, William Pooley, who contracted Ebola in August 2014 while working in an Ebola unit in Sierra Leone, was also treated at the unit after being airlifted from Sierra Leone. He recovered after being treated with an experimental drug ZMapp. According to reports, there are currently no supplies of ZMapp available anywhere in the world with which to treat Cafferkey. It is reported that Cafferkey was also to be offered blood plasma from a group of patients including Pooley, who have survived Ebola and is being offered an experimental anti-viral drug.

Cafferkey was one of the first groups of 30 volunteers sent out from the UK in November. Before departure, they were subject to psychological tests and intensive training, including nine days in simulated heat conditions wearing the many-layered restrictive clothing they would have to use in the field. The fact that one of the first volunteers has now contracted the disease raises questions about the efficacy of being able to safeguard future volunteers.

A December 31 Guardian article explains how Save the Children was put under pressure by the Department for International Development (DFID) to run the Kerry Town Ebola unit. Funding for the project comes from DFID. The building was constructed by the Sierra Leonean armed forces, directed by British Army Royal Engineers.

Although Save the Children had worked in Sierra Leone for many years, it did not have expertise in running an Ebola unit and said it would have preferred to have been able to scale up to such a task over a few years. On initially being asked to run the unit by DFID, Save the Children’s global humanitarian director, Michael von Bertele, explained, “Our reaction was—you must be crazy. My initial reaction was no. Then they pleaded with us.”

An Ebola treatment unit must be able to maintain a strict one direction of staff and patients, a one-way flow to lessen the risk of carrying the virus from a high risk area to a low risk area. Von Bertele had concerns about the layout of the unit. He told the Guardian that “we came out and made quite a lot of suggestions to modify it, but it was going up so quickly. … We would have made the wards bigger and probably changed the flow.”

Concerns have also been raised about the response in the UK to the Ebola threat. Cafferkey had originally told Public Health England (PHE) staff based at Heathrow of not feeling well and that she had been in contact with Ebola patients. Staff there measured her temperature seven times before pronouncing her okay to travel on to Scotland.

PHE has an Ebola screening unit based at Heathrow. Although there are no direct flights between the UK and West Africa, it is estimated that around 85 percent of passengers flying to the UK from West Africa will come through Heathrow.

Dr Martin Deahl, a British consultant psychiatrist, sat next to Cafferkey on the flight into Heathrow. He had also been in Sierra Leone, but based in a different unit to her. Speaking to the media, he raised concerns that the Ebola screening unit at Heathrow was not up to the task. He explained, “The staff were small in number and seemed inadequately prepared.”

He said that passengers who had travelled from Sierra Leone should have been given thermometers and kits to monitor their temperatures over the next three weeks, but that there was only enough to supply half of them.

Another health worker in Aberdeen, Scotland, who has recently returned from West Africa and became ill, has tested negative for Ebola. She is thought not to have had any direct contact with Ebola patients.

The outbreak continues to claim more lives. On the same day that Cafferkey was taken into hospital, dozens of new Ebola cases were discovered in Liberia along the border with Sierra Leone.

The recent UK cases demonstrate the growing threat of the Ebola virus to the world’s population. In October last year, Spanish nurse Teresa Romero became the first person to contract the virus outside of West Africa. In the same month, US officials announced that a second nurse at Texas Health Presbyterian Hospital involved in treating deceased Ebola patient, Thomas Eric Duncan, had tested positive for the disease.

The Ebola epidemic devastating West Africa is a product of the imperialist subjugation of the continent and the subordination of all social needs to the capitalist system and the profit motive that drives it. The lives of many people could have been saved if a drug had been developed in the four decades since Ebola was first discovered. That this has not happened is because the giant pharmaceutical companies that control medical research saw little profit in saving the lives of impoverished villagers in rural Africa.