Travel extending beyond 6 months is associated with health risks not usually encountered among short-term travelers, new data indicate.

Issues of most concern for long-term travelers are psychological problems and diseases caused by parasites.

Few studies have compared the types and causes of illness in travelers on the basis of duration of travel, Dr. Lin H. Chen, from the Mount Auburn Hospital in Cambridge, Massachusetts, and members of the GeoSentinel Surveillance Network note the journal Emerging Infectious Diseases.

Their study used data from ill travelers who visited GeoSentinel sites -- clinics on 6 continents that specialize in travel medicine - from 1996 through 2008. Included in the analysis were 4039 persons who traveled for more than 6 months and for 24,807 who traveled for less than 1 month.

Long-term travelers were significantly more likely than short-term travelers to have a variety of ailments including persistent fatigue, chronic diarrhea, malaria and post-infectious irritable bowel syndrome.

They were also much more likely to come down with leishmaniasis, a disease caused by a parasite transmitted by a tiny sandfly that can lead to severe scarring, and the parasitic worm disease schistosomiasis.

Many common infections seen in long-term travelers are preventable by vaccines, vector avoidance, food/water precautions, and avoidance of soil and fresh water, the researchers note.

Psychological diagnoses that were significantly more common in long-term travelers included depression, stress, and fatigue.

The increased number of missionary/volunteer/research/aid workers with stress was most significant, the investigators report.

Chen and colleagues point out that 70 percent of the long-term travelers in their study made pre-travel visits to health care providers.

Opportunities exist to educate, vaccinate, provide malaria chemoprophylaxis, and prepare these travelers for possible break-through infection, they conclude.

SOURCE: Emerging Infectious Diseases, November 2009.