Extensively Drug Resistant S. Typhi in Ontario Travellers Returning from Pakistan

Advisory Alert

May 14, 2019

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To community healthcare providers:

Re: Extensively Drug Resistant S. Typhi in Ontario Travellers Returning from Pakistan

I am writing to you today to provide you with information regarding an ongoing outbreak of extensively drug resistant Salmonella enterica serotype Typhi (XDR S. Typhi) in Pakistan and travel-related cases occurring in Ontario. This Advisory Alert highlights key clinical management considerations. Please consider salmonella infection in patients presenting to you with signs and symptoms compatible with infection and a history of recent travel to Pakistan and other areas in South Asia.

Background

Pakistan has been experiencing an outbreak of XDR S. Typhi since February 2018. As of December 2018, a total of 5372 cases have been reported, primarily from Karachi and Hyderabad. Travellers to Pakistan have also been affected. From July 2018 to-date, 9 cases of XDR S. Typhi have been reported in travellers returning to Ontario. A similar number of cases have been reported in the U.S. The strain associated with this outbreak is only susceptible to azithromycin and carbapenems.

Etiology and clinical presentation

Typhoid fever is an acute illness caused by the Salmonella enterica serotype Typhi bacteria. Symptoms of typhoid fever include fever (sustained), weakness, abdominal pain, headache, cough, loss of appetite, diarrhea or constipation and rash presenting as flat rose-coloured spots. More serious cases may experience bacteremia and sepsis, gastrointestinal and neurological complications.

Transmission

Typhoid fever is most often acquired by eating food or drinking water that has been contaminated with the feces of an infected person. This may include food or beverage contaminated by a person handling food, drinking water contaminated with sewage, eating shellfish taken from sewage-polluted areas, or eating raw fruits and vegetables fertilized with human waste. The incubation period is typically one to three weeks. The bacteria can survive for weeks in water or dried sewage. Approximately 3 to 5% of people become carriers of the bacteria after the acute illness.

Laboratory testing

Blood cultures and stool samples should be collected for bacterial culture. Please include travel history on the requisition. In addition to routine susceptibility testing, all S.Typhi isolates from travellers to Pakistan should be tested for carbapenem and azithromycin susceptibility. Samples can be forwarded to Public Health Ontario Laboratory (PHOL) for confirmation. Travel history and whether the isolate is XDR should be noted on the requisition. PHOL performs identification and full susceptibility testing.

Treatment

XDR S. Typhi is resistant to multiple antibiotics including chloramphenicol, ampicillin, trimethoprimsulfamethoxazole, fluoroquinolones, and third-generation cephalosporins. Patients with suspected typhoid fever and a travel history to Pakistan should be empirically treated with azithromycin or carbapenems based on clinical presentation pending full antimicrobial susceptibility testing results. Fluoroquinolones or ceftriaxone should not be used empirically for these patients. For patients with severe disease consultation with an infectious disease specialist is advised.

Prevention

Advise patients planning travel to obtain a travel medicine consultation as soon as possible before their trip, which may include assessment of the need for typhoid vaccine. Travellers should be advised that typhoid vaccine is ~ 50-80% effective and to exercise food and water precautions while abroad and be vigilant with hand hygiene. Risk of infection is higher for patients visiting and staying with friends and relatives than for business and tourist travellers.

Reporting

Report suspected and confirmed cases of typhoid fever promptly to Public Health Sudbury & Districts for follow up.

For all reporting, inquiries or comments, please contact Public Health Sudbury & Districts at 705.522.9200, ext. 464.

Sincerely,

Ariella Zbar, MD, CCFP, MPH, MBA, FRCPC
Associate Medical Officer of Health and Director, Clinical Services

This item was last modified on May 14, 2019