A genetic study of the bacteria that cause typhoid fever published Tuesday in the journal Lancet Microbe reveals that they have become more resistant to antibiotics and expanded over the past 30 years.
The researchers led by Jason Andrews, from Stanford University, in the United States of America, conducted the largest genomic sequencing operation of the S-Typhi bacteria, analyzing more than 7,500 different types, mainly from South Asia.
“The speed at which highly resistant strains of S-Typhi have emerged and spread in recent years is a real concern and illustrates the need to urgently scale up prevention measures, particularly in countries most at risk.”
Every year, 11 million people become infected and 100,000 eventually die from typhoid fever, with 70 percent of the world’s cases occurring in South Asia but impacting sub-Saharan Africa, Southeast Asia and Oceania.
One of the findings of the study is that resistant strains originating in South Asia have spread to other countries nearly 200 times since 1990.
Antibiotics can treat infections, but bacterial resistance is increasing in countries like those analyzed in the study, which include Bangladesh, India, Nepal and Pakistan, as well as samples isolated from more than seventy countries since 1905.
In all 7,658 sequenced genomes, genes were found that increase the bacteria’s resistance to antibiotics.
Since 1990, they have reached several countries in South and Southeast Asia, Southern and Eastern Africa, as well as the United Kingdom, United States and Canada.
The authors point to the scarcity of samples from areas such as sub-Saharan Africa and Oceania, where typhoid fever is endemic, as one of the limitations of their investigation.
The illness, which has several stages and lasts for weeks, causes high fevers, delirium, dehydration, exhaustion, weight loss, and skin irritation.
The main risk factors are lack of access to safe drinking water and sanitation.