Most U.S. measles cases occur in unvaccinated travelers who become ill after their return and spread the disease to susceptible individuals. Do you have patients who are unimmunized? Another point to consider when speaking with these parents about travel is the potential loss of the herd immunity afforded their children while living in the United States. This benefit may not exist when they are visiting and/or relocating to countries with lower immunization rates. Measles outbreaks are occurring in multiple countries and are not limited to underdeveloped countries. For the most up-to-date travel health-related information from the CDC, click here.
Travelers’ diarrhea (TD) occurs in up to 70 % of travelers to developing countries. The World Health Organization defines it as passage of at least three loose stools in a 24-hour period. Most often it is self-limited, with symptoms lasting a median of 3-4 days. Although TD can be caused by bacteria, protozoa, and viruses, bacteria are usually the etiology, with enterotoxigenic Escherichia coli being the most common pathogens. Other bacterial etiologies include Shigella and Campylobacter species. Two antimicrobials are frequently prescribed to travelers for self-treatment of TD: ciprofloxacin and azithromycin. Most young children are prescribed the latter; however, in older children, ciprofloxacin may be prescribed off label, as its use in persons younger than 18 years is not approved by the Food and Drug Administration.
In December 2014, PulseNet, the national molecular subtyping network for food-borne disease, detected a multistate cluster of ciprofloxacin-resistant Shigella sonnei. Between May 2014 and February 2015, 157 cases including 37 children were detected in 32 states and Puerto Rico. Nine of the cases identified by PulseNet, and an additional 76 cases, were associated with an outbreak of ciprofloxacin-resistant S. sonnei in San Francisco. Antibiotic susceptibility was available for 126 isolates, of which 109 (87%) were not ciprofloxacin susceptible. Travel history was available for 75 patients not associated with the San Francisco outbreak, and slightly more than half (40) were associated with international travel. The island of Hispaniola (Dominican Republic = 22 cases and Haiti = 4 cases) was the most common destination, followed by India (8 cases) and Morocco (3 cases). The remaining destinations were Asia and Europe (MMWR 2015;64:318-20) Travel history was available and positive for 23 of the 37 children (62%).
Why such a concern? International travelers are at risk of becoming colonized with drug-resistant bacteria and have the potential to spread them domestically. It has already begun. In 2012, the National Antimicrobial Resistance Monitoring System (NARMS) revealed that isolates of S. sonnei had the following resistance pattern: trimethoprim/sulfamethoxazole, 42%; ampicillin, 18%; and ciprofloxacin, 2.1%. During this outbreak, 19 of the 126 isolates were tested by NARMS with the following resistance patterns noted: trimethoprim/sulfamethoxazole, 84%; ampicillin, 5%; and ciprofloxacin, 32%.
More judicious use of antibiotics is necessary. As pediatricians, we are not immune to this issue. The challenge is when, if at all, antibiotics should be prescribed for TD, and under what conditions should patients be instructed to use them. I’m rethinking my own practice. TD is one of the most common illnesses travelers acquire and is easily treated, but at what cost? The one expression I keep hearing myself say is, First do no harm.
Dr. Word is a pediatric infectious disease specialist and director of the Houston Travel Medicine Clinic. She had no relevant financial disclosures.