I have been an immigrant, and have felt like an immigrant, most of my life. Even after living many years in one’s adopted country there is a very strong sense of another home, another place where home really is. And yet when one goes home, one is in many ways a foreigner there too. This sense of duality can be strange and disturbing but it can also be eye-opening and enriching. Being an immigrant is about experiencing change, sometimes for better, sometimes for worse. It is about feeling different, connected and disconnected. It is no surprise that the experience of immigration has so many connections to health.

There is a long history of receiving countries being obsessed with screening out “sick” immigrants: even today immigrants to many countries are asked to report if they carry certain infectious diseases including HIV/AIDS. As was amply evident during the recent Ebola epidemic, the immigrant is perceived as a public health threat because of the possibility he or she is bringing infectious diseases into the country.

In stark contrast to this notion of the sick immigrant, there is ample evidence that immigrants are generally quite a healthy bunch. This is not hard to understand given the many hurdles that immigrants face: only the healthier ones make it. This “healthy migrant” phenomenon has plagued research studies that attempt to understand the consequences of immigration for health.

Immigration itself does have important health consequences. We know that many immigrants progressively lose their so-called “healthy immigrant advantage” the longer they live in the United States. This has been attributed to exposure to environments that cause immigrants to change their diets in ways that are unhealthy, to adverse occupational exposures linked to the jobs that immigrants take on, or simply to the stress and social and cultural disruption associated with the transition to a new country.

The study of the changes in health associated with immigration has been critical not only as a way to understand the health of immigrants, but also as a window to understanding the causes of ill health more generally. Immigration can be used to study the health effects of environmental change. This was illustrated beautifully by studies of coronary heart disease among Japanese immigrants to the United States many years ago.

Of course immigration can also have favorable health consequences. Immigration can be life-saving. It can also mean expanded access to opportunities and resources critical to health (this is why many immigrants emigrate!). Immigrants can benefit from better access to health care, from access to jobs, and from living in environments where occupational and environmental regulation is the norm. 

But immigrants, whether legal or illegal, can also be stereotyped, discriminated against or threatened in subtle or not-so-subtle ways. This has enormous implications not only for the health of immigrants but also for the health of the broader communities where they live. And this is of special relevance today, given the growth of anti-immigrant feeling in the United States and, sadly, all over the world.

I recently heard from a public health practitioner that tuberculosis-infected immigrants were not coming in for checkups (and treatments) because of the threat of deportation. It is not hard to imagine that undocumented immigrants may be less likely to access health services or vaccinate their children if they perceive that doing so may increase the likelihood of being harassed or even deported. Further, even legal immigrants may feel threatened and reluctant to access services.

Research has shown that the mere threat of deportation has measurable health consequences: Latino women living in a community that experienced an immigration raid showed higher rates of low birth weight and prematurity, an effect that was not observed in a control sample of white women. These effects are not unlike the health consequences of discrimination and racism described in a large body of public health research.  

Today in the United States we are, unfortunately, undergoing a large “natural experiment” on the health consequences for immigrants resulting from stereotyping, threat, and discrimination.

As public health professionals what are we to do?

Last month I wrote that as public health professionals, it is our responsibility to "understand, advocate, and act." We must understand and document the broad health implications of this “natural experiment” for all of us; advocate for the principle of health as a human right including the rights of immigrants; and act to change things by disseminating our understanding and its implications through all venues available to us as professionals and as citizens, whether we are immigrants or not.