Doctors Notified About Highly Contagious Strain of Tuberculosis

The Centers for Disease Control and Prevention has warned doctors to look out for a highly contagious strain of tuberculosis that can be transmitted after only two hours of exposure. The CDC reports today in the New England Journal of Medicine that the bacterium can spread through casual contact--even outdoors, where the risk is ordinarily thought to be exceedingly low.

Twenty people were infected in a 1994-96 outbreak in rural Kentucky and Tennessee, but the aggressive strain has not reappeared since. Researchers do not know why it spreads so rapidly.

Compiled by Times medical writer Thomas H. Maugh II