Earlier this week, a group of scientists from the Yale University, in the United States, has revealed the real cause of the disease known as typhoid fever. As Alexander Fleming discovered penicillin by accident in 1928, so did the researchers from Yale University discover the true cause of typhoid fever. Typhoid fever is a common bacterial disease spread throughout the world. It is transmitted through the ingestion of food and water contaminated with feces containing the bacterium known as Salmonella Typhi. The disease accounts for more than 200 thousand deaths each year, however, its cause remained unknown until a study was published last week in the journal Nature.
According to the author of the study, professor Jorge Galan, typhoid fever is one of the oldest known diseases in the world. The disease is also credited with the devastation of Athens’ population and the winning of the Peloponnesian War by Spartans. Precedent research has shown that the bacterium responsible for the onset of the disease is Salmonella Typhi. However, its pathogenic pathways have not been understood for many years. Professor Galan affirms that researchers have been trying to understand why the bacterium is extremely pathogenic for years, despite the fact that the pathogenic pathways of other Salmonella have already been discovered and understood.
Dr Zulfigar Bhutta from the Aga Khan University in Pakistan, who is the leading typhoid fever expert, explains that one of the reasons why the cause of typhoid fever has remained undiscovered is that there are very few researchers working towards the discovery. Professor Galan and his team have revealed the mechanism through which S. typhi manages to keep its stealthiness for such a long period of time. According to the new paper, the bacterium only releases its toxin when it reaches the inside of the host cells. The reason why researchers haven’t found the toxin yet is because the conventional methods can’t discover it. Current conventional methods for detecting toxins is by growing the bacteria in the laboratory and then grinding them up. However, S. typhi doesn’t release its toxin unless it is inside the host cell.
However, Galan and his research team worked around the protocol when he wanted to observe the bacterium after infecting the host cells. According to Galan, his research team was investigating the interactions between human cells and S. typhi, nowise trying to find the S. typhi toxin. Once the bacterium penetrates the host cell, it begins to synthesize the toxin, releasing it into carrier vessels. The carrier vessels exit the cells and enter the blood system, where the toxin is released.
Subsequently after finding the compound that he thought would be the toxin of S. typhi, Galan isolated it and purified it. Further, he injected the compound into laboratory mice. All the laboratory mice that were injected with the newly purified compound developed typhoid disease symptoms, except fever, which is a symptom related to the presence of the bacterium inside the organism, rather than a symptom related to the actual toxin.
Dr. Bhutta affirms that Galan’s paper is fascinating. However, he believes that it is only the first step towards the correct direction. He says that further research is needed due to the fact that Galan’s study used mutant strains to S. typhi. Dr. Bhutta concludes that other research teams need to replicate Galan’s results before an official announcement regarding the cause of typhoid fever can be made.
Professor Galan says that an effective vaccine against the tested version of the toxin is trivial to synthesize. Current therapies against typhoid fever include a series of antibiotics that target the bacterium, and not the toxin.