Some critics of open borders are concerned that open borders will lead to the rapid spread of communicable diseases currently prevalent in the third world in first world countries, because the immigrants may themselves be infected with communicable diseases.

Here are some examples of these concerns:

Since this is not a very common criticism of open borders, it has not received much attention from open borders advocates. However, a comment by Vipul Naik on the Open Borders blog, and follow-up comments, explore the main counter-arguments. Here’s a quote of the original comment:

Chris, regarding the point you make about disease, I would add that the bigger danger is from tourism and short business trips, not from long-term migration. In the US, there are about 20X as many short-term business/tourist visits as the number of migrants (legal and illegal), as David Friedman documents here: http://daviddfriedman.blogspot.com/2006/03/immigration-and-terrorism.html

So a restrictionist who takes the disease argument seriously should wish to close down the borders not just to migrants, but to short-term business/tourist visas. I doubt even restrictionists would be willing to bite that isolationism bullet.

"The Efficient, Egalitarian, Libertarian, Utilitarian Way to Double World GDP" — Bryan Caplan