Doctors fear Ebola victim Patrick Sawyer may have sparked a worldwide spread of the killer disease after being allowed on two flights while infected.
And tonight a desperate race was on to find dozens of passengers who flew on the same jets as the 40-year-old American.
British doctors and border officials have been warned to be on the lookout for people in the UK showing signs of the disease.
Mr Sawyer was allowed to board an ASKY Airlines flight in Liberia, where Ebola is rife, despite vomiting and suffering from diarrhoea. His sister was recently killed by the virus.
He had a stopover in Ghana then changed planes in Togo and flew to the international travel hub of Lagos in Nigeria. The dad-of-three died five days after arriving in the city.
Lancaster University virologist Derek Gatherer said passengers, crew and airport ground staff who came into contact with Mr Sawyer could be in “pretty serious danger”. Ebola is fatal in 90% of cases.
Doctors have identified 59 people who were near him and have tested 20. But they are struggling to find the others, who could have flown to anywhere in the world from Lagos.
There were today questions over how Liberian government worker Mr Sawyer was let on flights while clearly showing symptoms of Ebola – which has killed 672 people in Liberia, Guinea and Sierra Leone since it broke out in February.
Experts from Public Health England have met UK Border Agency officials to make sure staff are aware of the signs to look for in Ebola sufferers.
PHE has also used its national medical alert system to advise all UK doctors to “remain vigilant for unexplained illness in those who have visited the affected area”.
Symptoms include vomiting and diarrhoea, fever, weakness, headache and sore throat.
Those struck down can also suffer internal and external bleeding. The virus is spread through human contact. There is no cure.