A new drug-resistant (XDR) strain of typhoid in Pakistan is just a small genetic step away from becoming completely untreatable—and health experts expect it to spread worldwide, thanks to extensive Pakistani migration and “asylum seekers” in western countries.
According to a report in the Arstechnica science magazine, Ttphoid fever, caused by Salmonella enterica serovar Typhi bacteria, is endemic to Pakistan, caused directly by “poor infrastructure, crowded urban areas, and insufficient access to healthcare.”
The epidemic caused by the XDR strain—the first of its kind—has been unfolding there since November 2016.
It has now affected at least 850 people in 14 districts, according to the latest figures from the National Institute of Health in Islamabad.
Prior to this epidemic, there were only four known, unrelated cases of such heavily drug-resistant typhoid, occurring in Iraq, Bangladesh, India, and Pakistan.
The XDR strain has already begun spreading outside of Pakistan, with a travel-related case appearing in the United Kingdom.
“It’s a global concern at this point,” Dr. Eric Mintz, an epidemiologist at the Centers for Disease Control and Prevention was quoted as saying.
“Everything suggests this strain will survive well and spread easily—and acquiring resistance to azithromycin is only a matter of time.” Azithromycin is currently the only antibiotic remaining that treats the infection.
In a recent report on the strain’s emergence in the journal mBio, infectious disease experts established that it could withstand assaults from five classes of antibiotics used to treat typhoid.
They concluded that the strain’s development was a “startling demonstration” of how easily S. Typhi can pick up genetic elements that confer drug resistance, “rendering it XDR and further narrowing treatment options.”
Antibiotics are the only effective treatment for typhoid fever, a systemic infection with varying severity that can become life-threatening.
The infection is generally marked by fever, headache, nausea, loss of appetite, and constipation or sometimes diarrhea. The heaviest death tolls are in children younger than age four. About 2 to 5 percent of those infected can become chronic asymptomatic carriers, shedding the bacteria in their feces. The Salmonella Typhi bacteria are typically spread through food or water contaminated with feces.
In the epidemic, researchers suspect leaking sewage lines were to blame for the creation and spread of the XDR strain.
Early disease mapping showed cases clustering around sewage lines in the city of Hyderabad. Researchers speculate that, within that seeping sewage, the aggressive MDR typhoid strain H58 encountered and picked up a circular piece of DNA (a plasmid) containing genes encoding additional drug resistance, likely from an E. coli strain or other enteric bacteria. This refuse rendezvous created the XDR strain.
“This isn’t just about typhoid,” said Dr. Rumina Hasan, a pathology professor at the Aga Khan University in Pakistan. “Antibiotic resistance is a threat to all of modern medicine — and the scary part is, we’re out of options.”
To preserve the last line of defense, public health officials have launched a campaign to vaccinate 250,000 children in Hyderabad using a new typhoid conjugate vaccine, Typbar-TCV, recently prequalified by the World Health Organization.
The vaccination campaign has faced local opposition, according to local news reports, amid rumors that the vaccines have been poisoned in a Western effort to harm children.
Similar suspicions have persisted since 2011, when a posed hepatitis B campaign helped gather intelligence before the Abbottabad raid that killed Osama bin Laden. Two polio vaccination workers were killed in Pakistan this January.