Editorial.Travel-Associated Infections – Epidemiological Risk
Published: 13.08.12 Updated: 13.08.2012 14:26:30
K. Kutsar, Editor-in-Chief
Citation: Kutsar K. Travel-Associated Infections as Epidemiological Risk. EpiNorth 2011; 12: 67-8.
Travel remains one of the largest businesses in the world despite the global threat of endemicity, emerging and re-emerging infectious diseases. For centuries infectious diseases have spread with the movement of people. International tourism is dependent on people who travel for holidays, leisure, recreation, business, visiting relatives and friends, education, health treatments, religious pilgrimages and other purposes. Today’s traveller may acquire infections such as HIV-infection, viral hepatitis, multi-resistant malaria and tuberculosis or leptospirosis. SARS-virus and pandemic A/H1N1/2009 influenza virus spread globally in a matter of weeks entirely by infected travellers and their contacts.
Travellers have been largely responsible for the transmission of infectious diseases into populations in which immunity has waned because of a decrease in indigenous disease cases and lack of routine adult vaccine boosters. Health problems of infectious etiology among travellers are frequent. Monthly incidence rates of infectious diseases among travellers in endemic countries include travellers’ diarrhoea 30-80%, ETEC diarrhoea 10%, malaria 2.5%, acute respiratory infection 1.5%, hepatitis A 0.3%, dengue fever 0.2%, animal bites with a risk for rabies 0.5%, hepatitis B 0.07%, gonorrhoea 0.06%, typhoid fever 0.03%, HIV-infection 0.01%, legionellosis 0.0005% and meningococcal infection 0.0001%. Poliomyelitis, although eliminated from most parts of the world, may still be associated with a wild poliovirus importation by asymptomatic persons from polio endemic countries (Afghanistan, Pakistan, India, and Nigeria).
Vaccine recommendations for travellers are based on the anticipated risks of exposure to vaccine-preventable diseases on a given travel itinerary and the severity of the infectious disease. Risk assessment should be based on factors that influence the risk of contracting an infectious disease while travelling. High risk factors are: geographical destination (developing countries), length of stay (long-term), location within country (rural), type of accommodation (economy), hygienic standard (low), purpose of travel (leisure), age of traveller (young) and type of travel (adventure). Recommendations for travellers are preferentially provided for persons travelling to countries that conduct surveillance of imported travel-associated infectious diseases and national immunisation registers.
The number of older travellers increases as the proportion of elderly in the population grows. Due to underlying diseases, older travellers may be more vulnerable to acquiring travel-associated infections and they should therefore have appropriate travel immunisation. Recommended vaccines may be less immunogenic in the elderly and the protective efficacy of many travel vaccines is unknown among this population.