Eight British soldiers have been flown out of Afghanistan after a "mystery fever" struck the main Allied air base, affecting 18 medical personnel.
The Ministry of Defence said last night that it had not identified the virus at Bagram air base near Kabul.
The two worst affected, who are in a "very serious" condition, were flown to hospitals in England and Germany. Six more, who are less seriously ill, left today, while another six remain under "barrier nursing supervision" at the 34 Field hospital at Bagram.
Lieutenant-Colonel Ben Curry, the British forces' spokesman, said that while four of the 18 patients were discharged, they are still among 333 people under quarantine at the hospital to prevent the disease spreading.
He acknowledged the army was dealing with a "serious situation" but said the events would not compromise operational capability. "It is a setback but it will not affect our military planning for future operations," he said.
Soldiers first started reporting symptoms similar to meningitis three days ago, but medics did not believe meningitis was to blame. The illness quickly proved to be contagious, with cases spreading rapidly. "Yesterday we had six, this morning we had 11, and by this evening we had 18," Lt-Col Curry said.
The Ministry of Defence said that the symptoms appeared to indicate some form of intestinal illness. A spokeswoman said: "The exact nature of the illness is not yet known and medical tests continue to isolate the cause. The symptoms are similar to gastroenteritis – fever, diarrhoea, vomiting. Those affected are all members of the medical staff and have varying degrees of the illness."
The 34 Field Hospital has been closed as a precautionary measure except to any further suspected cases of the illness that develop among the 350 people working in the vicinity.
The area around the hospital in the main Allied air base at Bagram, about 30 miles north of the Afghan capital, has been isolated and military police have been deployed to keep out trespassers.
Patients who were not displaying symptoms of the illness have been transferred to a German field hospital in Kabul. The ministry spokeswoman said the next of kin of the two most seriously ill soldiers had been informed. One is at an American military hospital in Germany while the other has been flown back to Britain.
The ministry insisted the illness had not resulted from any form of biological attack.
Last night, the Liberal Democrat defence spokesman, Paul Keetch, said the outbreak would do nothing to improve morale among the Royal Marines, who are already facing criticism that their operations have failed to find any al-Qa'ida or Taliban fighters.
"Disease has always stalked armies. It is no surprise to find it stalking our troops in the Afghan mountains," Mr Keetch said. "We must be assured that this outbreak is simply the unavoidable consequence of war and not a result of the shortfall of trained medical staff."
Bernard Jenkin, the shadow Defence Secretary, said: "It is important that the cause of the epidemic is found and isolated, and that those affected looked after in the best possible facilities. There are questions to ask and lessons to learn. Have there been any short cuts with hygiene and toilet facilities? Is Bagram using disposable cutlery and plates?"
Approximately 1,700 British troops are currently deployed at Bagram. They have been involved in two military operations in eastern Afghanistan since arriving in the country last month.Reuse content