Typhoid fever may be rare in developed countries, but this ancient threat, believed to have existed for thousands of years, is still very dangerous in today’s world.
According to new research, the bacterium that causes typhoid fever is developing drug resistance and is rapidly replacing resistant strains.
At present, antibiotics are the only effective treatment for bacterial typhoid fever. intestinal salmonella serovar Typhi (S Typhi). However, over the last three decades, the bacterium’s resistance to oral antibiotics has increased and spread.
By sequencing the genomes of 3,489 S Typhi strains in Nepal, Bangladesh, Pakistan, and India, which declined from 2014 to 2019, researchers recently found an increase in drug-resistant (XDR) Typhi.
XDR Typhi is not only resistant to advanced antibiotics such as ampicillin, chloramphenicol and trimethoprim / sulfamethoxazole, but is also resistant to newer antibiotics such as fluoroquinolones and third-generation cephalosporins.
Worse, these strains are spreading rapidly around the world.
Although most cases of XDR Typhi originate in South Asia, researchers have identified about 200 cases of international spread since the 1990s.
Most strains have been exported to Southeast Asia, as well as East and South Africa, but typhoid superbacteria have also been found in the United Kingdom, the United States and Canada.
“The rapid emergence and spread of highly resistant strains of S. Typhi in recent years is a real cause for concern and underscores the need for urgent expansion of preventive measures, especially for Stanford University infectious disease specialist Jason Andrews.
Scientists have been warning about drug-resistant typhus for years, but the new study is the largest genomic analysis of bacteria to date.
In 2016, the first XDR typhus strain was identified in Pakistan. By 2019, it had become the dominant genotype in the nation.
Historically, most strains of XDR typhoid have been treated with third-generation antimicrobial drugs such as quinolones, cephalosporins, and macrolides.
However, in the early 2000s, quinolone-resistant mutations accounted for more than 85 percent of all cases in Bangladesh, India, Pakistan, Nepal, and Singapore. At the same time, cephalosporin resistance was also present.
Today there is only one oral antibiotic left: macrolide and azithromycin. And this drug may not work for a long time.
A new study found that mutations resistant to azithromycin are still prevalent and “threaten the effectiveness of all antimicrobial drugs for the treatment of typhoid.” Although these mutations have not been accepted by XDR S Typhi, if they do, we will face a serious challenge.
If left untreated, typhoid fever can kill up to 20 percent of people, and today 11 million people are infected with typhoid fever each year.
Future epidemics can be prevented to some extent with the help of smallpox vaccines, but if access to these vaccines is not expanded globally, there may soon be another health crisis in the world.
“The recent emergence of XDR and azithromycin-resistant S Typhi requires accelerated preventive measures, including the use of conjugated vaccines against typhoid fever in endemic countries,” the authors write.
“Such measures should be taken in countries where the prevalence of antimicrobial resistance among S Typhi isolates is currently high, but should not be limited to such conditions, given the potential for international spread.”
South Asia may be the main center of typhoid fever, accounting for 70 percent of all cases, but if COVID-19 has taught us something, the variants of the disease can easily spread in our modern, globalized world.
To prevent this, health experts say governments need to expand access to typhoid vaccines and invest in research into new antibiotics. In India, for example, a recent study found that if children were vaccinated against typhoid fever in urban areas, it would prevent 36 percent of typhoid cases and deaths.
At present, Pakistan is leading in this area. It is the first country in the world to offer planned vaccination against typhoid. Millions of children were vaccinated last year, and health experts say more nations need to do the same.
Antibiotic resistance is one of the leading causes of death in the world, killing more people than HIV / AIDS or malaria. Where possible, vaccines are one of the best tools to prevent future catastrophes.
We don’t have time to waste.
The study was published Lancet microbe.