A doctor in France has tested positive for Ebola after returning from a humanitarian mission in the Democratic Republic of Congo.

The African country is struggling to contain a major outbreak of the deadly haemorrhagic fever, with known cases surpassing 1,000 earlier this week. At least 267 people, including 18 healthcare workers, have died.

On Wednesday, the French health ministry confirmed that a doctor who had recently returned from the region tested positive for the virus – the first case in France since the outbreak.

A statement added that the patient was immediately admitted to a specialist facility, and is in a stable condition.

It is not clear how many potential contacts will need to be traced, but French authorities stressed that the broader risk to the European population remained low.

It follows a recent scare in Israel after two people with a history of travel to the Congo exhibited Ebola-like symptoms. The health ministry confirmed on Tuesday that they both tested negative for the virus.

But the outbreak in East Africa is proving both devastating and hard to contain. The virus has already spread to Uganda, where 20 cases and two fatalities have been confirmed so far.

In the Congo, where the Ebola virus was first identified in 1976, the outbreak already ranks as the country’s second largest in history.

It is centred on Ituri province, a volatile and mineral-rich region in the country’s north-east, where misinformation is rampant.

As the virus took hold, so did rumours that it was a money-spinning hoax orchestrated by doctors, or that it was spread by witch doctors and cats.

The form of Ebola spreading is also rare, meaning there are no vaccines or treatments available, and the virus had been silently spreading for months before it was detected in mid-May.

This is partly because the tests available in the region could not identify this species of Ebola, which is called Bundibugyo. This strain also appears to be milder than others, which may have contributed to misdiagnoses in the early stages of the outbreak.

An assessment by the Congo’s ministry of health has suggested that about 90 per cent of patients do not develop severe internal and external bleeding. In the devastating 2013-2016 West African outbreak, where 11,000 people died of Zaire Ebola, roughly half of patients developed severe haemorrhaging.

“It makes total sense to me now how this was missed for months,” Dr Nahid Bhadelia, the director of Boston University’s centre of emerging infectious diseases, told The New York Times.

Although good for individual patients, this could make the outbreak more difficult to contain as symptoms are similar to other common diseases, including malaria, typhoid and dysentery.

This is especially dangerous for doctors and nurses, who may not realise that the patients they are treating are infected with the more serious virus.

According to the Congo’s national public health institute, at least 78 health workers have become sick and 18 have died during the outbreak. Last month, an American missionary doctor was also infected and transferred for treatment in Germany.

According to those responding to the outbreak, many of the doctors and nurses have been infected in ordinary clinics and hospitals – where there have been complaints about inadequate protective equipment – rather than the specialised Ebola treatment centres where infection control protocols are rigorous.

“Early symptoms such as fever, fatigue, muscle pain, headache and sore throat are non-specific, which complicates clinical diagnosis and can delay detection,” the World Health Organisation (WHO) said in a situation report on Friday.

“Differentiating [Bundibugyo virus] from other endemic febrile illnesses such as malaria is challenging without laboratory confirmation.”

In Ituri, where 90 per cent of cases are concentrated, authorities have made healthcare free to access to boost diagnosis and treatment, while lab capacity has been expanded and training for healthcare workers increased.

But the WHO warned that the outbreak was “unfolding in a complex humanitarian and conflict-affected environment”, and the proportion of contacts successfully identified dropped to 58 per cent during the weekend, compared to 70 per cent earlier last week.

“On a scale of zero to 10, compared with where this response needs to be, I would say we are at about three or four,” Marie Roseline Belizaire, the WHO Africa emergency response lead, told UN News.