International travellers face burden of tropical disease

International travellers need to reduce their risk of exposure to a heavy burden of disease in the developing world, specialists in tropical medicine say.

Dr. Jay Keystone, head of the tropical disease unit at Toronto General Hospital, and his colleagues looked at data from 17, 353 people who needed medical care during or after a trip to six developing regions.

Almost half the cases reported in this week's issue of the New England Journal of Medicine were immigrants returning to developing countries to visit relatives and friends, a growing category of travel after vacationers and business trips.

Each year, up to four million people, or eight per cent of travellers, visiting the developing world are ill enough to seek health care abroad or when they return home, according to background information in the study.

"Engaging travellers who are returning to their countries of origin for a visit is particularly difficult, since they often believe they have little risk of contracting disease in a place that was once their home," Dr. David Hill, director of the National Travel Health Network in London, England, said in a commentary accompanying the study.

"This mistaken belief has translated into disproportionate burdens of such diseases as malaria and typhoid fever in this group of travellers."

The editorial encouraged:

• The travel industry to inform customers of the health risks they may face.
• Doctors to publicize the benefits of pretravel medical care.
• Health-care systems to provide care specific to travellers visiting their countries of birth.
• Physicians to be educated in assessing the health risks of travel.

Travellers may need to take drugs and vaccines that fight malaria before, during and after trips.

In Ontario, drugs and travel advice from a doctor are no longer covered by medicare. The drugs can cost more than $1,000 for a family of four. About 25 per cent of the cases included in the study were presented at Keystone's clinic in Toronto.

The authors found major differences in illnesses between developing regions, data that should help doctors recognize what diseases they may see in returning travellers.

People returning from sub-Saharan Africa or Southeast Asia showed a disproportionate number of fevers, while acute diarrhea was more common among visitors to South-Central Asia.

In the Caribbean, Central or South America, skin diseases were more likely.

People visiting wealthier locales weren't immune. Legionellosis is often associated with hotel stays in the Mediterranean, norovirus outbreaks on cruise ships and crytosporidiosis from swimming pools, the editorial noted.

Travellers from every region except sub-Saharan Africa and Central America showed dengue more frequently than malaria, the researchers found.

Those travelling from all regions except Southeast Asia presented with parasite-induced diarrhea more often than bacterial diarrhea.