The first known epidemic of extensively drug-resistant typhoid has infected approximately 850 people in Pakistan across 14 districts since 2016 and is anticipated to disseminate globally, according to data from the National Institute of Health Islamabad cited by The New York Times.
Here are eight things to know.
1. The typhoid strain, which is resistant to five kinds of antibiotics, will replace weaker strains where they are endemic. Experts identified azithromycin as the only remaining oral antibiotic to fight this strain. However, one more genetic mutation could make typhoid untreatable in certain areas.
2. Researchers are viewing the epidemic as a call to implement comprehensive prevention efforts. If vaccination campaigns and modern sanitation systems fail to outpace the pathogen, researchers expect a return to the pre-antibiotic era, where mortality rates skyrocketed. "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."
3. Typhoid fever is a highly infectious disease transmitted by contaminated food or water and caused by the Salmonella Typhi bacteria. Symptoms include high fevers, headaches and vomiting. Around 21 million people suffer from typhoid each year, according to the World Health Organization.
4. The outbreak originated in the city of Hyderabad in India, where early case mapping showed victims clustered around the city's sewage lines. Researchers found water sources in the region that could be contaminated by leaking sewage pipes. Of the four deaths reported so far, at least one travel-related case was detected in the U.K.
5. Genetic sequencing revealed a multi-drug resistant typhoid strain called H58 interacted with another bacteria, likely Escherichia coli, and acquired an additional DNA molecule that coded for resistance to the antibiotic ceftriaxone.
6. In the Sindh province of Pakistan, physicians are treating the strain with azithromycin and more expensive treatments required to be administered in hospitals.
7. To preserve the last line of defense against the strain, public health officials launched a campaign to vaccinate 250,000 children in Hyderabad using a new typhoid conjugate vaccine. The vaccine lasts at least five years and children as young as six months old can receive it, according to the WHO. Experts are also reinforcing habits such as frequent hand washing, boiling drinking water and eating well-cooked foods.
8. "It's a global concern at this point," said Eric Mintz, MD, an epidemiologist at the CDC. "Everything suggests this strain will survive well and spread easily — and acquiring resistance to azithromycin is only a matter of time."