Beyond Central America, many developing countries are veritable Petri dishes of infection. Thankfully, many of the diseases, such as malaria, do not spread from person-to-person. But, some do. Hepatitis B, which is transmitted through body fluids like blood and semen, infects about 240 million people in the world, and more than a quarter of a million die every year. The virus is particularly prevalent in Africa and East Asia.

MERS, the deadly new virus similar to SARS that has killed at least 282 people, has already shown up in the U.S. Granted, the patients were travelers, not immigrants, but the threat is precisely the same. Many experts believe that it is merely a matter of time before Ebola — which has killed more than 600 in the ongoing outbreak in West Africa — turns up in the United States.

Simply put, an increasingly globalized world poses the very realistic threat of exotic diseases coming to the United States. It would be naive and irresponsible to pretend that immigrants, especially those from developing countries, pose absolutely no challenge to our public health system. Yet, that’s what Mr. Kluger implies when he refers to the “myth of the diseased immigrant.” He ought to know better; a brief scan of medical headlines proves he is incorrect.