A Nigerian doctor with Ebola carried on treating patients and met scores of friends, relatives and medics before his death, leaving about 60 of them at high risk of infection, the World Health Organisation (WHO) said on Wednesday.
Members of his church visited him in hospital in the oil hub Port Harcourt and performed a healing ceremony "said to involve the laying on of hands", said the U.N. agency.
"Given these multiple high-risk exposure opportunities, the outbreak of Ebola virus disease in Port Harcourt has the potential to grow larger and spread faster than the one in Lagos," the WHO said.
More than 1,900 people have died in West Africa in the world's worst outbreak of Ebola, WHO director-general Margaret Chan said earlier on Wednesday, marking a major acceleration in fatalities from just over 1,500 last week.
Nigeria's health minister said the country now had 18 Ebola cases, after a fourth case surfaced in Port Harcourt, which is home to many expatriate workers in major international oil companies.
The virus can be spread by direct contact with body fluids and secretions of an infected person or during traditional burial rituals, the WHO says.
The doctor, whom the WHO did not name, was infected by a man who fled quarantine in Lagos, who was himself linked to the first case in Africa's most populous country, a Liberian man who sought treatment in Lagos.
The doctor's wife and one of his patients had since caught the deadly disease and 200 people who came into contact with him were being monitored for symptoms including fever and muscle pain, followed by vomiting and diarrhoea, the WHO said.
Of these, around 60 are considered to have had high-risk or very high-risk exposure, it said.
Two days after developing the symptoms on Aug. 11, he went on treating patients at his private clinic and operated on two of them, the WHO statement said.
"Prior to hospitalisation, the physician had numerous contacts with the community, as relatives and friends visited his home to celebrate the birth of a baby," the WHO added.
During his six days in hospital before dying on Aug. 22, he came into contact with the members of his church and was "attended by the majority of the hospital's health care staff."
There is now a 26-bed isolation facility for Ebola cases in Port Harcourt, "with plans for possible expansion", the WHO said.
Travellers are being screened at domestic and international airport gates in the city, the capital of Rivers State, it said.
Efforts have been stepped up to educate the public about the disease with the help of local religious and community leaders, the WHO said.
"However, civil unrest, security issues, and public fear of Ebola create serious problems that could hamper response operations. Military escorts are needed for movements into the isolation and treatment centre," it said.
There is no cure or vaccine although an experimental drug made by a U.S.-based Mapp Pharmaceutical Inc. has been given to several patients who survived. The virus can kill up to 90 percent of those infected.