The Ministry of Defence has confirmed a case of swine flu at Catterick Garrison, Europe's biggest Army base.
A soldier is under quarantine at the base, where several other squaddies are also believed to be undergoing tests.
The soldier was based at Vimy Barracks and worked alongside scores of other servicemen and women.
A spokesman said the latest victim had mild symptoms and their condition was not giving cause for concern.
However, officers have ordered a clampdown on routine contacts -- with several contractors told not to visit the base until the swine flu alert is over.
The barracks has a population of around 12,000 service personnel and any outbreak would be a cause for serious concern with so many men and women working closely together.
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