Assessing risk of travel

The Traveller and Vaccination- assessing the risks.

Dr Jonathan Klotnick (MBBCh-Wits)

 

The risk of acquiring illness during travel depends on the areas or locations the traveller will be visiting and the extent to which the traveller is likely to be exposed to diseases in that area. The precise risk for a specific disease in a specific area or location has been difficult to predict despite several decades of interest and investigation. To estimate the exact number of cases of a disease or infection in all travellers over a period of time at a location is very difficult to determine as many travellers will have returned to their home countries by the time the disease manifests. There are formulas and models that are used to predict disease risk, but disease risk is not stable over time and the data available  regarding the incidence of disease risk in travellers is based on extrapolation of limited data collected in limited samples of travellers anywhere from a few to more than 20 years ago1. . These studies have their strength and weaknesses and thus there are limitations of current epidemiologic knowledge.  

The pre-travel state of health of the traveller and his or her expected behavior whilst travelling are important considerations to acquiring disease. The travel health professional needs to prioritize with regard to the incidence and severity of the infections that may be encountered.

To assess risk, it is important to know “why” people are traveling. Is it for business, leisure, to fulfill personal hobbies, for professional activities and it is also important to determine the duration of stay, environmental hazards, possible exposure to diseases and  the behavior patterns of the travellers- conservative or ‘risk takers’.

The hygienic standard at the point of the travellers destination is the more important point to consider than whether the traveller is going to be in a rural or urban area2. . For example: if two people were travelling and one was going  to a rural area  and the conditions are more hygienic than the other staying in a poorly kept place in an urban area, the fact that rural area is cleaner and more hygienic than the urban, the urban traveller would require more vaccine protection than the rural traveller. Tourists and business people with high standards of living are less likely to be exposed to disease than high risk travellers such as students who back-pack and stay at inexpensive places.