Drug-Resistant Typhoid Is Surging Worldwide, Research Warns of Growing Threat

Typhoid fever is an old bacterial illness that still threatens global health. Many people in developed nations assume the disease disappeared long ago. Yet this belief is mistaken because the bacterium never vanished worldwide. Instead, the disease remains common in many developing nations today.

Typhoid fever is caused by the bacterium Salmonella enterica serovar Typhi. The bacterium spreads through contaminated food or drinking water. Poor sanitation and unsafe water systems allow the infection to circulate widely. As a result, many regions still experience frequent outbreaks of the disease.

Researchers warn that typhoid fever is becoming more difficult to treat. A 2022 study published in The Lancet revealed troubling new trends. Scientists found that many S. Typhi strains are gaining resistance to antibiotics. This discovery raises concern because antibiotics remain the only effective treatment.

How Did Researchers Investigate S. Typhi Resistance?

To investigate the problem, researchers conducted a large international genetic study. They sequenced the genomes of 3,489 S. Typhi bacterial samples. The samples came from patients infected between 2014 and 2019. Researchers collected these samples in Nepal, Bangladesh, Pakistan, and India.

Genetic analysis showed that many typhoid strains carry antibiotic resistance genes. These genes allow the bacteria to survive treatments that once killed them. Some strains resist newer antibiotics used when older drugs fail. These include fluoroquinolones and third-generation cephalosporins, which doctors often rely on today.

Typhoid bacteria already resist several earlier antibiotics used for treatment. These older medicines include ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole. Doctors once used these drugs widely to treat typhoid infections. Over time, however, resistant strains gradually replaced the susceptible ones.

The study also revealed how resistant typhoid strains are spreading internationally. Most cases remain concentrated in South Asia, where infections occur most often. Yet the bacteria have crossed international borders nearly 200 times since 1990. Many of these transmissions occurred across Southeast Asia and East Africa.

How Was This Vaccine Tested?

Some resistant infections have also appeared in wealthier nations. Drug-resistant typhoid cases have been recorded in the United Kingdom. Similar infections have appeared in the United States and Canada. International travel and migration help these resistant strains move between countries.

Extensively drug-resistant typhoid emerged as a major concern during the past decade. The first known strain appeared in Pakistan during 2016. Within only three years, this resistant strain became the dominant typhoid form there. This rapid spread showed how quickly resistant bacteria can replace older strains.

Today only one oral antibiotic still works reliably against most typhoid infections. That remaining drug is azithromycin, which doctors increasingly depend on. Unfortunately, the 2022 study found genetic mutations threatening this final defense. These mutations allow the bacteria to resist azithromycin as well.

Researchers observed these resistance mutations spreading within affected communities. If azithromycin resistance becomes widespread, treatment options will shrink further. Doctors would then need intravenous antibiotics, which are harder to deliver globally. Many regions lack hospitals or medical systems capable of providing such care.

Untreated typhoid fever can be deadly for many infected people. Up to 20 percent of untreated infections eventually lead to death. In 2024, more than 13 million typhoid cases were reported worldwide. Such numbers highlight the continued scale of the disease globally.

Conclusion

Typhoid fever remains a serious global threat as antibiotic resistance spreads. Drug-resistant S. Typhi strains are rising and crossing borders worldwide. Vaccines, new antibiotics, and research are urgently needed to control the disease.

Have an upcoming trip? Passport Health offers a wide variety of options to help keep you safe from disease, including vaccines. Call or book online to schedule your appointment today.

Logan Hamilton is a health and wellness freelance writer for hire. He’s passionate about crafting crystal-clear, captivating, and credible content that elevates brands and establishes trust. When not writing, Logan can be found hiking, sticking his nose in bizarre books, or playing drums in a local rock band. Find him at loganjameshamilton.com.