Use of whole genome sequencing to complement characterisation of a typhoid fever outbreak among a Marshallese community: Oklahoma, 2015

• Published in: Epidemiology and infection Vol. 147; pp. 1 - e11
• Main Authors: Burnsed, L J, Kovar, L D, Angelo, K M, Trees, E K, Concepción-Acevedo, J, McDermott, M D, Wagner, D, Bradley, K K
• Format: Journal Article
• Language: English
• Published: England Cambridge University Press 01.01.2019
• Subjects: Antimicrobial agents; Citizenship; Communities; Disease control; Disease prevention; Electrophoresis; Epidemics; Epidemiology; Fever; Funerals; Gel electrophoresis; Gene sequencing; Genomes; Illnesses; Immigration; Infectious diseases; Medical laboratories; Outbreaks; Polymorphism; Public health; Pulsed-field gel electrophoresis; Questionnaires; Salmonella; Single-nucleotide polymorphism; Typhoid; Waterborne diseases; Atlanta Georgia; Micronesia; Georgia; Marshall Islands; United States > US; Oklahoma; epidemiology; emerging infections; Analysis of data; health statistics; community outbreaks
• ISSN: 0950-2688; 1469-4409
• DOI: 10.1017/S0950268818002601

Typhoid fever is an illness caused by Salmonella enterica serotype Typhi. In developing regions, it affects an estimated 20 million people annually, causing 200 000 deaths. Although uncommon, cases occur in the USA each year, predominantly due to international travel. During February 2015, the Oklahoma State Department of Health (OSDH) detected an outbreak of typhoid fever among residents of northwestern Oklahoma. OSDH conducted case-patient interviews to identify the source and symptomatic contacts. Whole genome sequencing (WGS) was performed to characterise the genetic relatedness of isolates among the four outbreak-associated pulsed-field gel electrophoresis (PFGE) patterns. We identified 38 cases, 25 confirmed and 13 probable, in two states. WGS revealed a 0-10 single-nucleotide polymorphism variation between isolates. Although we were unable to determine the source, almost all case-patients were members of the Marshallese community that attended a common event in Oklahoma, or were contacts to a confirmed case. This is the largest outbreak of typhoid fever in the USA since 1989, and first to apply WGS to complement interpretation of PFGE results during a typhoid fever outbreak investigation. This investigation illustrates the potential risk of outbreaks among communities comprised of international populations from regions where typhoid fever remains endemic.