A genetic variant associated with the risk of contracting typhoid fever is reported in a study published online this week at Nature Genetics. The results further our understanding of how the bacteria that cause typhoid fever interact with their human hosts.
Typhoid fever, also known as enteric fever, infects more than 26 million people each year, mostly in low-income countries. The disease is caused by particular strains of Salmonella and is usually contracted by eating or drinking food or water contaminated by feces. Without treatment, 10-25% of those who become sick will die.
In order to understand why some people who come in contact with the bacteria become sick, while others do not, Sarah Jane Dunstan and colleagues compared the genetic makeup of infected and uninfected people from populations in Vietnam and Nepal. They found one genetic variant, HLA-DRB1*04:05, that confers nearly fivefold greater protection from the disease than the alternative variant of the same gene. The variant is found in the HLA region, which is a cluster of genes on chromosome 6 that encode proteins responsible for regulating the immune system.