A deadly version of an intestinal germ has spread through sub-Saharan Africa, helped by genetic mutation and diseases such as HIV that weaken the immune system and expose the body to infection, researchers said Sunday.The finding comes in a genetic comparison of variants of Salmonella Typhimurium, one of the Salmonella family of stomach bugs.In sub-Saharan Africa, a new form of the germ emerged in the southeast of the continent 52 years ago, followed by a second wave, which came out of central Africa 17 years later, the researchers said in a new study published by the journal Nature Genetics.The variant is the cause of an enigmatic disease called invasive non-typhoidal salmonella (iNTS), which affects Africa far more than other continents.iNTS kills between 22 and 45 percent of those it infects and is suspected to be transmitted from human to human, previous research has found.Outside Africa, Salmonella without this variant tend to cause acute diarrhoea but the death rate is less than one percent. And these infections typically occur from contaminated food, not from humans.AFP