September 30, 2012
A nastier kind of salmonella infection has emerged alongside the HIV epidemic in Africa. The finding is the first evidence that HIV might be allowing new human pathogens to evolve in immunosuppressed people.
Most people who get salmonella contract it from eating contaminated meat, leading to an unpleasant but brief gut upset. But in Africa, the bacteria escapes into the blood of people with suppressed immune systems, causing a fever called invasive, non-typhoidal salmonella (iNTS) that can kill in up to 45 per cent of cases. The main victims used to be children who have immune deficiency as a result of malnutrition or malaria, but iNTS is also a classic complication of HIV.
Chinyere Okoro of the Wellcome Trust Sanger Institute in Hinxton, UK, and colleagues fully sequenced the DNA of iNTS samples from Africa, then used that to analyse the family trees of the bacteria sampled across the continent. The team found they nearly all clustered in one of two closely related lineages.