LONDON - Smallpox, one of the world's deadliest diseases, eradicated three decades ago, is kept alive under tight security today in just two places - the United States and Russia.

伦敦——天花曾是世上最令人闻风丧胆的致命疾病之一，但这种疾病已在30年前被根除。如今，在严密的安全控制下，天花仍还在两个地方“活跃”——美国和俄罗斯。