Author: Malick Gibani

The mystery of the typhoid toxin

Typhoid toxin

Dr Malick Gibani unravels the mystery behind the role of typhoid toxin in causing typhoid fever  – a disease that affects around 11 million people each year globally.


Salmonella Typhi is a fascinatingly complex bacterium. Whilst there are more than 2000 different (sero)types of Salmonella, there’s something special about Salmonella Typhi that sets it apart from the non-typhoidal Salmonella serovars. It causes different symptoms, the means of spread are different and the host it infects is different – specifically, Salmonella Typhi only causes disease in humans.

Understanding the mechanisms of how bacteria can cause disease is profoundly important for vaccine development. The Vi-antigen that forms the major component of injectable typhoid vaccines seems to have a key role in making the bacteria more virulent (hence the name). Vi-based vaccines have proven to be highly effective tools to prevent typhoid. (more…)