Low levels of important nutrients like selenium can turn a benign virus into its virulent form, claim American scientists.

Researchers Melinda Beck and her colleagues at the University of North Carolina in Chapel Hill, say that Keshan disease - a fatal virusinduced disease that causes inflammation of the heart muscles - is endemic to China, where the grain is deficient in selenium (New Scientis4 Vol 146, No 1978).

The researchers are speculating if the emergence of HIV could also have a selenium link. The clue lies in that the virus is thought to have originated in Zaire, where the people have been found to have low levels of selenium in their blood.