A British aid worker suffering from the highly infectious disease Lassa fever has died in hospital.
Ian Janeck contracted the virus while working on a contract for the Department for International Development in Sierra Leone. His wife was by his bedside at Coppetts Wood Hospital, Muswell Hill, north London, when he died.
He initially responded to treatment after arriving at the unit two weeks ago. He had been transferred from University College London's Tropical Diseases Hospital.
Mr Janeck, of Chatham, Kent, was placed on a ventilator and at first made some progress, but during the past week his condition deteriorated and he developed heart failure, the spokeswoman said.
Lassa fever derives its name from the Lassa area of Nigeria - where the first case was reported.
It is mainly transmitted by rodents but can be passed on by an infected person. It tends to be transmitted to humans through exposure to the urine and faeces of infected animals.
People are only infectious while symptoms are present or in the period of convalescence and then only through direct contact with bodily fluids.
Since 1970 there have been at least 12 cases of Lassa fever imported into Europe or North America - but there have been no reports of onward transmission to other people.
The symptoms of Lassa fever tend to last between one and four weeks.
It is characterised by a soaring temperature, headache, lethargy and severe muscular pains. Temperatures can reach 41C.
There is also often a rash due to bleeding into the skin and mucous membranes.
More serious complications can occur, such as respiratory distress, brain inflammation and internal bleeding.
Lassa fever has a high mortality rate and is particularly dangerous to pregnant women.
The fatality rate among patients with a serious infection being treated in hospital is 15-20%.
However, treatment with anti-viral drugs can reduce the fatality rate.