Since 2016, five children in the United States have been diagnosed with extensively drug-resistant typhoid fever after traveling to or from Pakistan, where a large ongoing typhoid outbreak has sickened more than 5,300 people, according to a report published today in MMWR.
The outbreak in Pakistan involves a Salmonella enterica serotype Typhi strain that is resistant to most antibiotics commonly used to treat the illness, researchers said. The MMWR report states that 29 patients diagnosed in the U.S. with typhoid fever had traveled to or from Pakistan during 2016 to 2018, including the five children with extensively drug-resistant (XDR) infections.
“It’s important for travelers and clinicians to know that all travelers to Pakistan are at risk of getting extensively drug-resistant typhoid fever, which can be very difficult to treat,” Kevin Chatham-Stephens, MD, MPH, FAAP, a medical officer in the CDC’s Division of Foodborne, Waterborne, and Environmental Diseases, told Infectious Disease News. “Travelers to South Asia, including Pakistan, India, and Bangladesh, should take precautions to protect themselves from typhoid fever.”
According to Chatham-Stevens and colleagues, between November 2016 and September 2017, 339 infections caused by the XDR Typhi strain were reported in Pakistan, with one travel-related case also reported in the United Kingdom. Enhanced surveillance efforts in Pakistan identified a total of 5,372 cases as of Dec. 30.
Chatham-Stevens and colleagues reported that the U.S. also has increased surveillance, resulting in the identification of the 29 patients with typhoid fever linked to travel to Pakistan. The children diagnosed with XDR Typhi were aged 4 to 12 years and had traveled to or from Pakistan during late 2017 through mid-2018.
Every year in the U.S., about 350 culture-confirmed typhoid fever cases are reported to the CDC, according to Chatham-Stephens and colleagues. Worldwide, the annual number of typhoid fever cases is around 12 to 27 million, they said. The researchers advised clinicians to be aware that most typhoid fever infections in the U.S. are nonsusceptible to fluoroquinolones — which they said should not be used as empiric therapy — and that the outbreak strain is susceptible to only azithromycin and carbapenems.
In an email, the CDC said it was “concerned” that the outbreak strain also would become resistant to azithromycin, making it harder to treat in areas without access to certain IV antibiotics.
Chatham-Stephens and colleagues said further travel-related cases may be prevented or treated through efforts to promote pretravel vaccination, improved surveillance, including rapid reporting of XDR Typhi cases, and the use of alternative empiric treatments. Chatham-Stephens advised that individuals traveling to South Asia visit a doctor or travel clinic 2 weeks before travel to receive vaccination against typhoid fever.
“Always follow safe food and water guidelines during travel, and if you get sick, see a health care provider as soon as possible,” he said. “Doctors should consider typhoid fever in sick patients who have recently traveled to or from Pakistan.” – by Marley Ghizzone
Disclosures: The authors report no relevant financial disclosures.