Ebola may be spreading faster than first thought, WHO doctor warns

An Ebola outbreak which has killed at least 131 people in the Democratic Republic of Congo may be spreading faster than originally thought, a World Health Organization (WHO) representative has warned.

Dr Anne Ancia told the BBC that the more the agency investigates, the clearer it becomes that cases have spread to other areas.

Officials said more than 513 cases were suspected in DR Congo as of Tuesday, while one person has died in neighbouring Uganda.

But modelling by the London-based MRC Centre for Global Infectious Disease Analysis released on Monday suggested there had been "substantial" under-detection, and that it could not rule out there had already been more than 1,000 cases.

WHO chief Tedros Adhanom Ghebreyesus, who declared the outbreak an international emergency last week, said he was "deeply concerned about the scale and speed of the epidemic".

It is feared the outbreak may have been ongoing for several weeks before it was first detected on 24 April.

There is no vaccine for the strain of Ebola virus fuelling the latest rise in cases, but the WHO is evaluating whether other drugs may provide protection.

Speaking to BBC World Service Newsday, Ancia said DR Congo's Ituri province, the epicentre of the outbreak, is a "very unsecured area with lots of movement of population", making it difficult for the agency to investigate and help control the disease.

She continued: "The more we are investigating this outbreak, the more we realise that it has already disseminated at least a little bit across border and also in other provinces."

The outbreak has spread to the province of South Kivu, where the population has been affected by a humanitarian crisis for many years, she added.

There has also been a case in eastern DR Congo's biggest city, Goma, which has a population of around 850,000 people and under the control of Rwandan-backed rebels.

High levels of insecurity in several provinces mean people move around often, increasing the risk and spread of the virus.

Several African countries are taking precautions by tightening border screenings and preparing health facilities. Neighbouring Rwanda has also closed its borders with DR Congo.

An American citizen, believed to be missionary group doctor Peter Stafford, is being evacuated from DR Congo after developing symptoms over the weekend.

Germany's health ministry told the BBC a US citizen was being taken to the country for treatment.

The US Centers for Disease Control and Prevention (CDC) said it was working to evacuate at least six other Americans who were exposed.

Ebola is caused by a virus and initially causes symptoms similar to the flu, with fever, headache and tiredness.