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Influenza sans frontieres « Back to Blogs

Infectious disease pandemics start in a single country and then spread – slowly or quickly – around the world until they become global.

The enablers for their spread are human beings. This has led many to postulate that, if you can diagnose and treat a patient with an infectious disease at the border before they enter a country, then you will prevent spread from one country to the next. 

This makes sense in theory but there are many reasons why it doesn’t usually work in practice. Selvey and colleagues have detailed many of these reasons in their paper on entry screening for infectious diseases in humans. (1)

 A short summary is that it is difficult to screen for patients at the border: tests will miss some patients who have infectious diseases and will sometimes suggest a serious illness when there is none. Some patients may be in the incubation period of the infection and so have no symptoms or signs at all. Screening at the border is also expensive in terms of resources – both financial and human resources. It may be better to focus these efforts on strategies that have been proven to be effective – such as vaccination or social distancing. 

Is there anything that we can do at the border that might help? It may be that communication with travellers is a more effective measure. “Informational videos, posters, signs, in-flight announcements, flyers, and health alert notices” can be used to tell travellers about symptoms of infection and what to do if they feel unwell. Do these measures work? They seem to have a positive albeit small influence on the behaviour of travellers. But they must be backed up with systems in place so that if travellers do have a fever, they know what to do and where to get help. 

It is a cliche that infectious diseases don’t recognise borders but it is true. However human beings do recognise borders and so it might be worthwhile trying to communicate with them so that they will change their behaviours and help prevent the spread of infectious diseases. The next global pandemic infectious disease may well be an influenza pandemic – one of the challenges will be to educate the travelling public before, during and after such a pandemic. 



  1. Selvey LA, Antão C, Hall R. Entry screening for infectious diseases in humans. Emerg Infect Dis. 2015 Feb;21(2):197-201. 

Competing interests 

KW works for BMJ which produces a range of resources in infectious and non-infectious diseases. 



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