Waging War Against Traveler’s Diarrhea for U.S Troops Overseas

Posted 15 November 2016

For the average traveler, bouts with diarrhea are so common that the term “traveler’s diarrhea” is casually used to describe what some consider just a typical hazard of adventures abroad.  But for the U.S. military, traveler’s diarrhea spreading through the troops can become a significant barrier to carrying out a military mission, said Mark Riddle, with the Naval Medical Research Center in Silver Spring, MD.
That’s why a team of U.S. military medical researchers launched an extensive trial evaluating whether a single dose of an antibiotic administered alongside the drug loperamide (the active ingredient in Imodium) can put a stop to a condition that is at best exhausting—but which can also quickly cause dehydration requiring hospitalization.  
Riddle noted that in the U.S., most physicians who encounter a patient with diarrhea assume it’s caused by a virus and don’t prescribe antibiotics, which are not effective against viruses. That practice has carried over to military medical professionals, he said, even though in many countries, diarrhea is just as likely to be caused by a bacterial infection that’s often treatable with antibiotics.
But antibiotics have their own issues, Riddle said. High doses can add nausea to the diarrhea symptoms. There is also the concern that overuse of antibiotics is contributing to a rise of resistant pathogens.
To provide evidence for guiding clinical decisions, Riddle and his colleagues, with support from the Uniform University of the Health Sciences, in Bethesda, MD,  spent three years studying more than 339 patients in Kenya, Afghanistan, Djibouti, and Honduras who were experiencing “acute watery diarrhea.” They were treated with loperamide and just a single dose of either azithromycin, levofloxacin, or rifaximin antibiotics. In each arm of the study, a large majority of patients were cured within 24 hours: 80.2% of the levofloxacin arm, compared to 78.3% and 74.8% in the azithromycin and rifaximin arms, respectively.
“What (the data) show is that when you combine an antibiotic with loperamide, you get a rapid resolution of symptoms for moderate to severe disease,” Riddle said. “This is important for decreasing the risk of dehydration and getting travelers back to functioning.”
Riddle said only a few patients experienced any nausea or vomiting from the antibiotics. The main challenge for the military, he said, will be to make antibiotic therapy more easily available from medics who cannot currently prescribe the drugs. He said military officials also could consider making antibiotics accessible to troops going out on patrol.