Chapter 3Infectious Diseases Related To Travel

Ezra J. Barzilay, Ryan P. Fagan

INFECTIOUS AGENT

Helicobacter pylori is a small, curved, microaerophilic, gram-negative, rod-shaped bacterium.

MODE OF TRANSMISSION

Exact transmission is unknown, but it is thought to be fecal-oral or possibly oral-oral.

EPIDEMIOLOGY

H. pylori infection is one of the most common bacterial infections in the world. Estimated prevalence is 70% in developing countries and 30%–40% in the United States and other industrialized countries. Infection usually occurs during childhood and may persist lifelong unless treated. Humans are the only known reservoir. No increased risk of H. pylori seroconversion has been documented among residents of industrialized countries who traveled to developing countries for up to 16 months. Among missionaries and long-term travelers to developing countries, the annual incidence of seroconversion is 1.9%, which is higher than the annual incidence of seroconversion (0.3%–1.0%) in industrialized countries.

CLINICAL PRESENTATION

Most people infected with H. pylori never develop symptoms. H. pylori is the major cause of peptic ulcer disease and gastritis, which most commonly presents as gnawing or burning epigastric pain. Less commonly, symptoms include nausea, vomiting, loss of appetite, or bleeding. Rarely, and primarily in older adults, H. pylori is associated with a gastric lymphoma of the mucosal-associated lymphoid tissue.

DIAGNOSIS

Testing is recommended for patients with active gastric or duodenal ulcers, gastric mucosa–associated lymphoid tissue lymphomas, or those who have undergone resection of early-stage gastric cancer. Esophagogastroduodenal endoscopic biopsy is performed to obtain tissue samples for histologic identification of organisms, culture, urease test, antibiotic susceptibility testing, and PCR. Active infection can also be diagnosed with a ¹³C- or ¹⁴C-labeled urea breath test or with a fecal antigen detection assay. H. pylori–specific IgG (serum or salivary antibody) is a useful marker for epidemiologic studies of past or current infection, but its sensitivity is suboptimal. A positive antibody screen should be confirmed by a different test (such as fecal antigen, urea breath test, or endoscopy).

TREATMENT

In the United States, the recommended primary therapies are 14 days of clarithromycin-based triple therapy (proton pump inhibitor [PPI] + clarithromycin + amoxicillin or metronidazole) or 10–14 days of bismuth quadruple therapy (PPI or H₂-blocker + bismuth + metronidazole + tetracycline). Detailed information about these and other recommended treatment regimens is available in the American College of Gastroenterology Guideline on the Management of Helicobacter pylori Infection (www.acg.gi.org/physicians/guidelines/ManagementofHpylori.pdf).

PREVENTIVE MEASURES FOR TRAVELERS

Because the mode of transmission is not known, there are no specific recommendations to prevent H. pylori infection. No vaccine is available, and no drugs for preventing infection are recommended.

BIBLIOGRAPHY

1. Becker SI, Smalligan RD, Frame JD, Kleanthous H, Tibbitts TJ, Monath TP, et al. Risk of Helicobacter pylori infection among long-term residents in developing countries. Am J Trop Med Hyg. 1999 Feb;60(2):267–70.
2. CDC. Helicobacter pylori fact sheet for health care providers. Atlanta: CDC; 1998 [updated 2010 Oct 22; cited 2008 Nov 30]. Available from: http://www.cdc.gov/ulcer/files/hpfacts.PDF.
3. Chey WD, Wong BC. American College of Gastroenterology guideline on the management of Helicobacter pylori infection. Am J Gastroenterol. 2007 Aug;102(8):1808–25.
4. Gold BD, Colletti RB, Abbott M, Czinn SJ, Elitsur Y, Hassall E, et al. Helicobacter pylori infection in children: recommendations for diagnosis and treatment. J Pediatr Gastroenterol Nutr. 2000 Nov;31(5):490–7.
5. Lindkvist P, Wadstrom T, Giesecke J. Helicobacter pylori infection and foreign travel. J Infect Dis. 1995 Oct;172(4):1135–6.
6. Peterson WL, Fendrick AM, Cave DR, Peura DA, Garabedian-Ruffalo SM, Laine L. Helicobacter pylori-related disease: guidelines for testing and treatment. Arch Intern Med. 2000 May 8;160(9):1285–91.
7. Potasman I, Yitzhak A. Helicobacter pylori serostatus in backpackers following travel to tropical countries. Am J Trop Med Hyg. 1998 Mar;58(3):305–8.