Typhoid gene unravelled

Lead researcher, Dr Sarah Dunstan from the Nossal Institute of Global Health at the University of Melbourne said the study is the first large-scale, unbiased search for human genes that affect a person's risk of typhoid.

Enteric fever, or typhoid fever as it more commonly known, is a considerable health burden to lower-income countries.

This finding is important because this natural resistance represents one of the largest human gene effects on an infectious disease.

"We screened the human genome to look for genes associated with susceptibility to, or resistance from typhoid.," Dr Dunstan said.

"We found that carrying a particular form of the HLA-DRB1 gene provides natural resistance against typhoid fever. This gene codes for a receptor that is important in the immune response, by recognising proteins from invading bacteria."

Typhoid is contracted, by consuming food or water contaminated with the bacteria, Salmonella Typhi or Paratyphi. It has been estimated that typhoid causes 200,000 deaths a year globally, and infects 26.9 million people per year.

"If we can understand this natural mechanism of disease resistance, then we can use this knowledge to help develop improved vaccines for typhoid fever, but also potentially for other invasive bacterial disease,"

Better treatments and vaccines are needed for typhoid fever as the infecting bacteria are getting increasingly more resistant to antibiotic treatment, and the current vaccine is only moderately effective and does not protect against paratyphoid fever, which is increasing within Asia.

This work was conducted in patients from Vietnam with findings then replicated in independent patient cohorts from Vietnam and Nepal

The research collaboration was between the Genome Institute of Singapore and Oxford University Clinical Research Units in Vietnam and Nepal.