By Philip R. Fischer, MD, DTM&H

Professor of Pediatrics, Division of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, MN

Dr. Fischer reports no financial relationships relevant to this field of study.

SYNOPSIS: In addition to issues of malaria, vaccination, and trauma in travelers, viral diseases and the management of diarrhea were key topics at the biannual meeting of the International Society of Travel Medicine in Barcelona, Spain, during May 2017.

Celebrating its 25th anniversary, the International Society of Travel Medicine looks back on decades of establishing and advancing the field of travel medicine. With a certifying exam, a focused medical journal, a robust research network, regional and international conferences, and a growing (3,500) membership, this organization continues to lead at the frontier of ensuring that travelers have safe and healthy international experiences. A total of 1,543 participants from 68 countries met in Barcelona. Some aspects of the May meeting are noted here to give readers of Infectious Disease Alert a view of some new advances in the field of travel medicine.

Viral Diseases

Arthropod-borne virus infections, including Zika, dengue, and chikungunya, have garnered recent headlines in the popular press. The vectors’ lives are not shortened despite ongoing infection; this allows them to spread the infection to many animals or humans. Human hosts usually are “dead-end” victims without high enough levels of viremia to allow further spread of illness. Symptoms overlap, as fever, musculoskeletal pain, and rash occur with each of these infections. Reverse polymerase chain reaction testing can identify infections. Symptomatic care can be helpful.

Up to half of the million people who contract chikungunya each year go on to develop chronic pain that can persist for up to six years. Patients often have synovitis with edema, but actual joint effusion is less common. Bilateral distal joints usually are involved symmetrically, and larger proximal joints can be involved after the first six months of illness. Physical therapy is helpful; acetaminophen helps with pain; low-dose steroids sometimes are offered, although steroid use has not yet been proven to be effective.

Several neurotropic viruses are common. Japanese encephalitis virus mostly affects children in Asia (although there was a recent report of a case in Africa). Acutely, about 10% of affected subjects have brain involvement; about half of infected individuals fully recover. West Nile virus infection of the nervous system is more common in adults, especially immunocompromised adults. West Nile virus infection, even with meningitis, usually resolves without neurologic sequelae; two of three anecdotally treated Israeli patients seemed to be helped by intravenous immune globulin.

The effects of the West Africa Ebola epidemic linger, even as Ebola is now active again in the Democratic Republic of the Congo. There is emerging evidence of post-Ebola arthralgia with fatigue and some visual changes. Sequelae are most common in those who experienced seizures or melena with the initial infection. Ebola antigen has been identified in semen in about 25% of subjects nine months out from symptomatic infection and has been found up to 500 days after recovery. While not all detectable antigen represents live virus, sexual transmission has occurred six months after a man recovered from Ebola. Ocular symptoms are identified in 60% of Ebola survivors, with 18% with uveitis.

Nearly 2,000 cases of Middle Eastern Respiratory Syndrome Coronavirus (MERS-CoV) have been identified in 27 countries; 81% of cases are tied to Saudi Arabia. Camels are clearly linked to infection, but 27% of subjects lack known camel contact and contact with someone known to be ill. Some affected individuals seem to be especially contagious; one returned traveler was linked directly to 153 of the 186 patients who had MERS-CoV in a South Korean outbreak. Thus far, no MERS-CoV infection has been linked to the Hajj, probably because of careful camel restrictions with that event.

Travelers’ Diarrhea

No controversy was greater in Barcelona than that of antibiotic use for presumptive management of travelers’ diarrhea. It is well-established that bacterial diarrhea is common in travelers, affecting about 30% of those visiting resource-limited countries. It is accepted that antibiotic treatment with azithromycin, even in a single dose, can shorten the duration of illness. And, it has been common practice to provide a prescription of an antibiotic during pre-travel consultations so that treatment can be started quickly in the event of a bothersome bout of travelers’ diarrhea.

In recent years, however, it has been well-documented that travelers undergo changes in the intestinal microbiome, often with emergence of multi-resistance enteric pathogens. Former travelers then risk the development of subsequent resistant infections, and communities risk more rapid global spread of antimicrobial resistance. Antibiotic treatment augments the travel-related risk of developing antimicrobial resistance in the intestinal flora.

Research and practice leaders generally agreed that travelers with mild diarrhea who don’t experience any change in planned activities can allow their self-limited gastrointestinal infection to run its course without using antibiotics; loperamide or bismuth subsalicylate can provide some symptomatic relief. At the other end of the spectrum, travelers with severe diarrhea (fever, bloody diarrhea, bed-bound) should receive antimicrobial therapy (with a single 1,000 mg dose of azithromycin usually being fully effective for adults, otherwise 500 mg daily for up to three days in adults). The controversy arose about self-treatment of moderate bouts of diarrhea (not severely sick but unable to participate in some planned activities). While newly released guidelines1 say that “azithromycin may be used to treat moderate travelers’ diarrhea,” some thought that “may” was too permissive and encouraged overuse of antibiotics, while others said “may” was too restrictive when all suffering travelers with diarrhea should receive helpful antibiotic treatment.

Provision of Pre-travel Care

A survey of 100 primary care providers in 35 U.S. states revealed that most felt uncomfortable providing pre-trip care. Their discomfort was not unreasonable since most were unable to identify accurately which vaccines would be useful, and most were not able to advise accurately about the prevention and management of travelers’ diarrhea.

A community program was established to determine how best to provide care to West Africans traveling from Minnesota to visit friends and relatives. There were high levels of engagement by community members, and culturally appropriate surveys and strategies were developed.

In general, travelers are satisfied with multi-faceted input during pre-travel consultations. In a Swiss survey, travelers were satisfied with the information they received about malaria, diarrhea, rabies, and fever. However, they did not feel adequately informed about safety, sexually transmitted infections, and skin protection. Professionals providing pre-travel care should be adequately knowledgeable about all aspects of travel health, capable of clear educational presentations of information for travelers, and organized with adequate time to provide comprehensive pre-travel care.

In Indiana, a statewide vaccine registry helped give necessary immunizations and avoid repeat doses of vaccines in children visiting a travel clinic. Electronic systems can facilitate improvements in efficiency and quality of care.

Data about acute mountain sickness were presented on two posters. Acetazolamide did not seem to alter the incidence of symptoms significantly in either travelers in Peru or in travelers from Spain. Of course, further study will be needed before abandoning the use of acetazolamide to prevent mountain sickness.

REFERENCE

  1. Riddle MS, Connor BA, Beeching JN, et al. Guidelines for the prevention and treatment of travelers’ diarrhea: A graded expert panel report. J Travel Med 2017;24 (Suppl 1):S57-S74.