Traveler's Diarrhea: A Volunteer's Aggravation

Rifaximin, (Xifaxan R): A New Treatment Consideration for Traveler’s Diarrhea.
Traveler’s Diarrhea certainly remains one of the major medical problems confronting short-term missionaries. The most common causative agents are coliform bacteria that are the usual inhabitants of the intestinal tract, but cause diarrhea in patients who are not immune to the enterotoxins which some strains produce or because of the tendency of some types to adhere to the wall of the intestine. (See the article on Enteraggregative E. coli following). Although usually not a cause of serious illness, traveler’s diarrhea can significantly interfere with participation in mission and productivity, and may become a major problem in small children or patients with chronic underlying medical problems such as diabetes or immune deficiency. Those patients who require prolonged Rx with H2 blocking agents for GE reflux disease are uniquely susceptible to traveler’s diarrhea because lowered gastric acidity deprives the body of its first line of defense. In situations such as these, prophylaxis should be considered. In recent years ciprofloxacin (Cipro) has been the most widely used antibiotic for treatment and prophylaxis, and coliform bacteria have thus far not shown a major resistance pattern. Rifaximin (Xifaxan), used in Europe for a number of years, has recently been FDA approved for treatment of diarrhea caused by non-invasive forms of Coliform bacteria. A number of clinical trials have shone a success rate comparable to Cipro. Unlike Cipro, it is not absorbed from the GI tract. Because of this lack of absorption, side effects are few, and because of its more limited use, resistance is less likely to develop. The drug is fairly expensive, comparable in price to brand name Cipro. Unlike Cipro it is not effective against any of the dysentery organisms, such as Salmonella/Shigella and Campylobacter. Rifaximin should not be considered either as treatment or prophylaxis in areas with a high incidence of Campylobacter. Rifaximin may be considered as a treatment or preventive alternative to Cipro, but in the event of fever, blood in the stool or worsening diarrhea, rifaximin should be discontinued, and an alternate antibiotic selected.
Roger Boe MD
UMVIM Medical Consultant

Ref: DuPont, H. Therapy for and Prevention of Traveler’s Diarrhea. Clinical Infectious Diseases 45: 2007 Suppl S78-84.

Enteroaggregative E. Coli: An Under-recognized Cause of Traveler’s Diarrhea
The majority of cases of traveler’s diarrhea are caused by variants of the common coliform bacteria that are usual inhabitants of the intestinal tract. It has been assumed in the past that the typical illness (self-limited watery diarrhea without fever), was caused by enterotoxins that some strains produce in persons who were not immune to that particular toxin. Recently another type of E. coli has been widely identified as a cause of diarrhea in travelers. Called Enteroaggregative E. Coli, it has been identified in many developing countries. In a recent study involving travelers to Mexico, it was demonstrated as the causative agent in 25% of cases. Similar findings have been reported in many developing countries. This organism has also been discovered to be the cause of a number of outbreaks in industrialized nations. There is rising evidence that it is involved in a large number of deaths in young children, particularly in the presence of malnutrition. The incidence of Enteroaggregative E Coli infection is most likely vastly underestimated, as awareness of this newly discovered threat is low, and diagnostic testing is not as yet widely available. These bacteria cause illness by adhering to cells in the wall of the small and large intestine. A thick film of mucus is formed, allowing the bacteria to persist and multiply. There is also some evidence of a low-grade inflammatory reaction. Infection produces a more protracted course than with the enterotoxigenic strains, often lasting 7-14 days. Mucus production is characteristic, and a significant minority of patients will have blood in the stool, and/or low-grade fever, making clinical differentiation very difficult between this coliform infection and disease caused by Campylobacter and Salmonella. Diagnosis can be established by demonstrating the aggregative effect (AA) after incubation with tissue culture cells. A DNA probe has also been developed. At present these tests are available for research application only, as they are expensive, labor intensive, and time-consuming. Treatment with floxacin antibiotics, azithromycin, or rifaximin has thus far been uniformly successful. It is important for us as short-term health volunteers to be aware of this new wrinkle in the management of traveler’s diarrhea, and also to be aware of the real danger that infection with Enteroaggregative E. coli poses for malnourished children.
Roger Boe MD
UMVIM Medical consultant
Ref: Nataro, J.P. Enteroaggregative Escherichia coli, Emerging Infectious Diseases, 4 #2, 1998