Traveler’s Diarrhea and Hepatitis
Conference Coverage
Reviewed by Lin Chen, MD
Synopsis: Nearly 2000 participants gathered in Montreal, Québec, for the 6th Conference of the International Society of Travel Medicine. Important travel recommendations were provided including reviews of traveler’s diarrhea and hepatitis.
Sources: Tornieporth N, et al. In: Abstracts of the 6th Conference of the International Society of Travel Medicine: p. 39, FC1.1.; Mathewson J, et al. In: ibid: p. 39, FC1.2.; DuPont H. In: ibid: p. 67, S12.2.; Caumes E, et al. In: ibid: p. 48, FC4.2.; Shlim DR, et al. In: ibid: p. 40, FC1.5.; Carroll B, Behrens RH. In: ibid:p. 113, M02.
The incidence of traveler’s diarrhea (td) seems to have remained unchanged in the past decade. A worldwide evaluation of TD (TRADIWOW) was conducted between 1996 and 1998, and this was the core of a number of presentations on enteric infections and TD at the 6th Conference of the International Society of Travel Medicine. TRADIWOW was a cross-sectional survey of homeward bound travelers at the airports of Mombasa (Kenya), Goa (India), Montego Bay (Jamaica), and Fortaleza (Brazil). The Jamaican arm of the study was reviewed recently in Travel Medicine Advisor Update (Chen LH. TMA Update 1999;9:19-21). Traveler’s diarrhea attack rates ranged from more than 30% in Kenya and India to 6.0-13.4% in Brazil. Attack rates were highest in persons younger than 30 years of age, in honeymooners, and in travelers from the United Kingdom. The risk increased with the length of stay and was associated with certain hotels. Seasonal variation of TD was demonstrated only in Jamaica, and most patients admitted to risky eating behavior (FC1.1, S12.1).
A second part of the TRADIWOW study assessed the etiology of TD. Stools from patients with TD were examined. A pathogen was identified in 32% of TD cases from Montego Bay and 76% of TD cases from Goa. Enterotoxigenic coli (ETEC) was the most common cause at both sites, although toxin production and colonization factor antigen patterns showed some differences. Salmonella and Shigella were also frequently identified from Goa in samples (10% and 11.4% of patients, respectively). Salmonella was identified in 7.8% of patients in Jamaica and Shigella in 0.3%. Parasitic pathogens were identified more frequently in Goa than in Montego Bay visitors (8.1% vs 1.6%) (FC1.2, B02, B04).
Quality of life was evaluated by questionnaire as part of the TRADIWOW study and showed that TD led to significant impairment of a person’s quality of life (B03). Concurrent with the TD study in Montego Bay, the Jamaican Ministry of Health implemented environmental health and food safety standards at sentinel tourist hotels in an attempt to control TD. The TD attack rates from 1996 and 1998 were compared and suggested a decrease from 24.6% to 16.6% (FC1.3).
DuPont reviewed drug resistance in pathogens of TD. There is widespread resistance in these organisms to ampicillin and doxycycline. Resistance to trimethoprim/sulfamethoxazole has increased greatly in Vibrio cholerae, Shigella sp., Campylobacter jejuni, Salmonella (typhi and nontyphoid spp.), and ETEC. In some areas, the resistance rate has exceeded 90% for C. jejuni, 50% for Shigella, and 20-40% for nontyphoid Salmonella and ETEC. Rates of quinolone resistance for Campylobacter vary by region, from 13% in the United States to 84% in Thailand. New agents being evaluated for TD include rifaximin, pivamdinocillin, and azithromycin (S12.2).
Four cases of surgical complications of TD were presented in a free communication session. The patients initially had TD and were treated abroad with both loperamide and antibiotics. They subsequently developed cecal perforation/peritonitis (2 patients) or necrotizing right-sided colitis (2 patients). These cases suggested caution in the use of loperamide in severe TD (FC4.2).
On a more encouraging note, the declining rates in travel-associated hepatitis A infections in U.K. residents during 1990-1997 were presented in a poster. Rates had been markedly higher for visits to the Indian Subcontinent compared to Mediterranean countries. The rate decreased from 6.0/10,000 visits in 1990 to 0.4/10,000 visits in 1997 for travel to India. The infection rate for visits to Turkey decreased 60% during this period. Prescriptions for hepatitis A prophylaxis increased six-fold from 1990 to 1997. The declines in travel-associated hepatitis A can be attributed to increased prophylaxis as well as decreased transmission of hepatitis A in these high-risk areas (M02).
Shlim discussed the risk of hepatitis E infection among expatriates in Nepal. A total of 383 persons enrolled in a study at the CIWEC Clinic Travel Medicine Center between June 1997 and December 1998, and had blood samples tested for hepatitis E and hepatitis A antibodies. Only one study participant developed symptomatic hepatitis E, a calculated rate of 261/100,000, with no asymptomatic seroconversion. There were only 12 persons who were seronegative for hepatitis A at enrollment, and they were all seronegative for hepatitis E. There were 10 persons who were positive for hepatitis E antibodies, and they were also positive for hepatitis A antibodies. The overall rate of exposure to hepatitis E appeared low among foreigners living in Nepal during this study period, however there were 12 other cases of hepatitis E detected at the same clinic from 1994 to 1998 (FC1.5).
What does all this information mean to the travel medicine practitioner? Traveler’s diarrhea continues to be a significant problem. The advice regarding food and water safety remains crucial, although travelers often do not heed the advice. The emergence of resistance to quinolone antibiotics calls for consideration of new agents for the empiric treatment of TD, and the choice of agents may vary by region. Furthermore, caution should be used regarding the use of loperamide in severe TD. Finally, the declining trend in travel-associated hepatitis A infections brings optimism that prophylaxis is making a significant difference, and that an effective vaccine prophylaxis against TD might also be welcomed. (Dr. Chen is Clinical Instructor, Harvard Medical School and Travel/Tropical Medicine Clinic, Lahey Hitchcock Medical Center, Burlington, MA.)
References
1. Ashley DVM, et al. In: Abstracts of the 6th Conference of the International Society of Travel Medicine: p. 40, FC1.3.
2. Cavalcanti AM, et al. In: ibid: p. 77, B02.
3. Stephenson B, et al. In: ibid: p. 77, B03.
4. Verenkar MP, et al. In: ibid: p. 77, B04.
5. Von Sonnenburg F. In: ibid: p. 67, S12.1.
Which of the following is correct?
a. Hepatitis E infection appears to be uncommon among expatriates in Nepal.
b. The incidence of travel-associated acute hepatitis A virus infection among U.K. residents is rising dramatically.
c. Trimethoprim-sulfamethoxazole remains the antibiotic of choice in the empiric treatment of traveler’s diarrhea.
d. Resistance to quinolone antibiotics among Campylobacter species remains rare in traveler’s destinations such as Thailand.
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