migration and health: the challenge of causality and implications for action

8/8/2019 Migration and Health: The Challenge of Causality and Implications for Action

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Just as a bit of background, I am a Demographer and Sociologist by training,though my tenure as Director of the Global Health Affairs Program has allowedme to delve into the epidemiologic side of health AND the broader politicaleconomy of health: the narrative frames, biases, and power dynamics throughwhich we view health and disease.

And now a caveat. I have conducted a great deal of research on patterns ofmigration and migrations impact on health, particularly for populations leftbehind by migration.

I have also studied HIV/AIDS. I have studied the vicious cycle linkinghomelessness and HIV/AIDS in the US. And I now study the impact ofHIV/AIDS on the health and welfare of affected families in South Africa.

But you may have noticed that I have never actually looked at migration andHIV/AIDS together. With good reason. The migration to HIV/AIDS link is atremendously challenging subject that raises deep moral and politicalconcerns. The United States and South Africa share, moreso than mostcountries, a near obsession with blaming public health problems on vulnerablecommunities, migrants among them. I thus come to this symposium with sometrepidation about the thin line between the humanitarian approach to infectiousdisease and the securitization of migrant health.

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Here is my official financial disclosure slide. I have absolutely nothing to report.I am not a clinician but I hope that my perspective will prove enlightening asyou all embark on an impressive two-day program.

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As a social scientist, the best way I know to help is to try and highlight thespecific pathways linking migration to health, which is the primary goal of mytalk. Is migration bad for your health? (Pause)

This question does not lend itself to a clinical trial.

2) The answer is highly dependent on processes of self-selection intomigration. Whomigrates often ends up being just as important as the actualeffect of migration.

3) I will conclude by setting out some Hippocraticprinciples for addressing

migrant health in a clinical or social context.

4) And just to set the stage for an exploration of migration and health, CalWilson asked me to include a bit of background on migration levels, countriesof origin, and areas of destination. Fortunately some of my amazing studentsat DU had just prepared a presentation on the US migration system, and so Ihave appropriated their slides and give special thanks to Megan Banick,Shreesh Bhattarai, and Erica Rosenfield.

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Is migration bad for your health? (pause) Depends on who you ask.

A helpful starting point for understanding the migration-health nexus is to understandourselves and our narratives. This stylized graph offers a way to map migration

narratives according to two key value distinctions. The x-axis is the continuum ofintellectual interest, from humanistic, qualitative narrative on the left to scientific,quantitative evidence on the right. As a deeply personal experience for so many,migration provides many stories, but it also produces a considerable amount ofstatistical data, at least in some instances. The y-axis shows a continuum ofpolitical identity, from a commitment to free markets on the bottom to socioeconomicjustice at the top.

1) Anthropologists and advocates set migration in a narrative of what goes wrong when

free-roaming capital and globalization grab an unsuspecting and vulnerable target.False hope, mortgaged land, HIV/AIDS, and television sets for poor nations.Exploitation for the migrants. And lost jobs in the host society.

2) Economists, on the other hand, often find positive effects. This is what shouldhappen when capital-rich, labor-poor societies find cheap sources of labor, and theoccasional tragedy is just part of the statistical error term.

As a demographer utterly bereft of an indigenous theory to call my own, I tend to move

between each of these perspectives, and end up in the center. I will let you all find yourown place on this graph.


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Before we assess the effect of migration on health, we need toestablish a study population. Who is affected by migration?

Of course it is the migrants themselves who bear the risks andreap the benefits of migration most directly.

But decades of research on the social, economic, andbiophysical connections between migrants, their hostcommunities, and those they leave behind have forced us to

view migrant health within this broader continuum of migration-affected populations. To be clear, it is not just that the leftbehind are affected by migration, it is that they are in fact veryactive participants in the process as initiators, financiers, anddistributors of the returns.


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So what is this migration thing?

Before I turn to migration and health, let me provide somebackground on immigration in the US. Here is the total number oflegal immigrants to the US by year from 1820 to 2007. The patternmay be familiar to many. A massive migration peak straddles theturn of the 20th century, before the gates were shut tight in a wavenativist anger, restrictive laws, and two world wars. Migrationreemerged with the Bracero program, which brought Mexican guestworkers during and after World War II, and has risen steadily ever

since. Today the annual number of legal arrivals almost equals1900. That number constitutes a much smaller share of todays

vastly greater population, but these numbers also dont even

include undocumented arrivals.

So migration is big, at least by historical standards.

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So where do migrants come from?

Two patterns dominate the trend in national origins of US immigrants.

1) On the one hand, the US foreign-born population has come toinclude a broader and broader representation of the worlds nations.

This began with the 1965 Immigration and Nationality Act, whichreopened the US to migrants of non Western European origin. Itaccelerated with the opening of the Diversity Visa lottery program in1995, which offered permanent US residency to a select few

applicants from countries not previously represented in the Americanethnic quilt.

2) Even as the US migrant population has grown more diverse in termsof number of countries represented, it has also come to include anunprecedented number of people from a single country, Mexico,which alone accounts for 30% of the foreign-born population. Thoughperhaps some folks would be surprised that the Mexican share is not

even higher.

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The regional share of the foreign-born further illustrates the

diversity of todays immigrant population as well as the dominance

of migrants from Latin America, who together constitute 54% of theforeign born.

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People are probably pretty familiar with where migrants move to.

The lions share of the foreign born live in six large states that also

have a high percentage foreign born, led by California and followedby Texas, New York, Florida, Illinois, and New Jersey. Californiaalone accounts for about one quarter of the entire US foreign bornpopulation. As you see, Colorado is also moderately high. Butimmigration rates and foreign born populations are rising in a greatmany states with little history of immigration, particularly in the deepsouth.

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Because of the dominance of migrants from Mexico, the map of theforeign born looks quite similar to the map of the Mexican born.Migrants from Mexico dont just dominate the overall flow, they also

dominate the literature on migration and health in the US andglobally, which can present challenges for producing generalizableknowledge.

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So, back to the question. Is migration bad for your health?

From a standpoint of pure epidemiology we can classify the effects of migration,both positive and negative, as economic; occupational or environmental; andbehavioral.

1) Economic relates both to the positive and negative effects of increased incomeand to the potential risks of unemployment or debt.

2) Next, migrants face many occupational or environmental risks in the workplace,in their homes, and in their communities.

3) Finally, and of greatest interest for this conference, migration may induce

changes in behavioral risks such as unsafe sex, drug abuse, or smoking.

In the journal AIDS, Organista and colleagues offer an illuminating account of howthe nature and impact of these proximate risks will be determined primarily by thecontext of migration. First comes the socio-cultural context of the migrant-sendingcommunity and the community of destination, including cultural practices, socialsupport networks, and patterns of vulnerability and resiliency.

Above that is the structural context. This includes the legal rights of migrants (orlack thereof), including documentation status. Related to legal regime are theconditions of the migrant journey itself and of segregation on arrival.

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Okay, before we try to answer our question the right way, lets look at how existingresearch has viewed migrant health. In a highly illuminating 2007 study byCunningham and colleagues reviewed 74 existing studies covering a total of 34mortality and 196 morbidity findingson the migration-health relationship.

Of these 230 total findings, just over a half compared the health of migrants to thehealth of natives. From an epidemiologic standpoint, this comparison could be usefulfor understanding the unmet health needs of migrants, but in general the comparisonis unfair and unhelpful in understanding the health of migrants. A causal research

design normally looks within a comparable group and identifies those factors thatlead some to have poorer health than others. But migrants are not pulled from acomparable population; rather they joined this population, coming from a diverserange of nations and ethnic backgrounds, and generally from greatly disadvantagedcircumstances. Truly an unfair comparison.

Most of the remaining findings reviewed by Cunningham and colleagues take thesomewhat more reasonable approach of comparing migrants to their native co-ethnicpopulation, for instance comparing Mexico-US migrants to US-born Mexicans,

including those whose families have been here 400 years. A closer comparison, butstill not quite apples to apples.

Many people in the room will already know the common, consistent and replicableresult of this unfair comparison ( drum roll please ) On most dimensions of health

and in most comparisons, migrants have better health outcomes than natives.

Let me repeat that. Migrants have better health than natives. (Wake up)

From mortality to morbidity. Adult to perinatal. Communicable to noncommunicable.Migrants have better health than natives in about three-quarters of all comparisons.

(Uh oh)


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A similar migrant advantage pertains to direct comparisons between migrantsand the US born co-ethnics, as seen in this example from a paper by GopalSingh and Robert Hiatt in the International Journal of Epidemiology in 2006.

Using data from the National Health Interview Survey and the National DeathIndex, they report differences in life expectancy at birth for natives and non-natives among three race/ethnic groups. For women, we see that Latinamigrants have a two-year advantage over US-born Latinas and black migrantshave a 6 years advantage over Us-born black women. Differences are smallamong white women, but favor the immigrants slightly. Note also that bothmigrant and US-born Latinas live considerably longer than white women.

These basic relationships held for both men and women and for specificmorbidity outcomes.


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So in spite of some incredibly poor risk factors like poverty -- immigrantsactually have better health outcomes than natives.

But this is a pretty unhelpful comparison. The US-born comparison groupscome from highly diverse backgrounds and it is really not clear how migrantsshould compare to them.

Comparison of migrants to natives not only prevents us from making a faircomparison, but it keeps us from distinguishing between two clear hypothesisthat could explain the immigrant health advantage

1) First is the role of self-selection. Migrants may be so healthy simply

because only someone who is healthy in the first place could endure themove

Anyone who has been through DIA security can attest to that!

2) Alternatively, perhaps there is something about the social, cultural, andstructural context of migration or migrant communities that actually allowsthem to remain healthy, which would have even more profound implications formigrant health programming.

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As in any observational study, we really need to tackle theselection issue before we can get causal.

After controlling for selection, we should be able to comparethe health of migrants to reasonably comparable individualsfrom the same population who did not migrate, AKA the leftbehind.

Of course we would also need to account for the fact thatthe left-behind themselves might be affected by migration.More on that later.


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We start with selectivity, and here we begin to explore the nexus of structural,sociocultural, and individual factors.

The legal, historical, and logistical context of migration sets the stage for migrantselectivity.

- Is it a hard trip? Then there may be more health selectivity as only the hardiest

can make the trip. Or it might just attract those who with a penchant for risk.

- Is it a skilled migration flow? Then educational selectivity might be exceptionallyhigh, as in the case of migration from India to the US.

- Is migration simply a matter of buying a visa and a plan ticket? Then selectivitymight be financial, as in the case of guest worker migration.

- Finally, do political or environmental conditions in the sending community pushmigrants out of the home area, as in the case of refugee flows? Then theselection might be less extreme, because everyone has to leave, but we might

start to ask what factors of selection leave some displaced people in the nextvillage over, some in a camp a hundred miles away, and some in Denver.

Structural factors dont just determine who moves within a community, but which

communities send migrants. Does a migration system encourage migration fromcommunities fragmented by racism, injustice, and displacement, as in Apartheidand post-Apartheid South Africa?

Or does it encourage migration from tightly knit communities that are able torecreate their social world in the destination and to recruit more and more folksfrom home to join them, as has been the historical case in Mexico?

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Recently a few studies have begun to explore migrant health selectivity bycomparing recent migrants to the left-behind. The Mexican Family Life Surveyactually surveyed a large random sample of Mexicos population, measured

health, and then followed everyone 5 years later, even if they found their way to

the US. A 2008 paper by Luis Rubalcava and colleagues shows the surprisinglylimited extent of selectivity. The blue bars are the inter-survey migrationprobabilities of those in poor health based on a variety of reported and observedhealth markers, orange bars indicate the migration of those in excellent health,so this is capturing the absolute extremes of variation. For women, those inexcellent health are two to three times more likely to migrate than those in poorhealth, sizable but not overwhelming. For men, the force of selection is evenweaker and, in the case of urban men, it is actually negative, with men in poorhealth more likely to migrate than those in excellent health.

Of course, this is only one mode of selectivity in migrant health. There may alsobe selectivity in return migration, with the healthier more likely to remain in theUS and thus to be surveyed. Second, selection on community strength,financial resources, or educational attainment may be equally important forlong-term health as initial health. Finally, this study, like most studies of migranthealth in the US and indeed the world, focuses on the Mexico-US migrationexperience, which is both wildly overrepresented in the research literature andquite unique. While the risks of the Mexico-US trip might demand greater

physical fitness, the well-traveled pathways and strong social ties linking Mexicoand the US might also make the move more accessible to all.

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A paper by Cynthia Feliciano offers some insight into just how unique theselectivity context of Mexico-US migration is. She calculates a Net DifferenceIndex comparing US immigrants from specific countries to their originpopulations, basically the extent to which migrants have higher levels of

education than the left-behind, with 1 meaning that every single migrant wouldhave more schooling than every single non-migrant and 0 meaning that arandomly selected migrant would likely have the same level of schooling as arandomly drawn non-migrant.

A typical migrant from Mexico would have a 20% chance of having moreschooling than a typical non-migrant, a pretty minor difference that mirrors theRubalcava result. For India, by comparison, a typical migrant would have an 85%chance of having more schooling than the typical Indian, meaning that migrants

from India bear almost no resemblance, at least in schooling terms, to theirformer compatriots.

A quick bit shameless self-promotion: To address the gap in research on migranthealth, I have the great opportunity to join my colleague Fernando Riosmenafrom CU-Boulder on an exciting new project that will broaden our understandingof migrant health by looking at migrants from China, India, the Philippines, theDominican Republic and of course Mexico. The goal, of course, is not really to

address health selectivity in migration, but to move past selectivity andunderstand what happens to migrant health next.

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Whatever the extent of selectivity might be, we are finally, at long last, ready tothink about our original question. Is migration bad for your health? (Ugh)

We again compare migrants to the left behind.

1) We would first want to account for the individual economic effects of migration.Migrants may be able to buy more health care with their resources, but they alsobuy more junk food. They might experience an economic crisis. These migrantresources can also affect the health of the left behind, for instance if monetaryremittances are sent home. The closer we get to comparing a migrant to anindividual who is actually comparable, say a non-migrant from his own villagerather than just some person from a random sample of the entire country, themore likely it is that the left-behind persons health is also affected by migration.

Ill get back to that in a minute.

2) Next we move to the contextual side. Much of migrant health are programmedwell in advance by the origin community context. This includes the migrants prior

child development and health-seeking behaviors at the time of departure. Incomparing a migrant to a left-behind member of the same community, we couldassume both would be affected by the origin context in similar ways.

3) And so one major change is that as the migrant spends more and more time inthe destination community, his or her current health will come to be more andmore determined by the destination context rather than the origin context.

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4) Of course its not quite that simple. First, that destination context may look an

awful lot like the origin context in a great many ways if the destination communityconsists largely of people from home, a so-called ethnic enclave. Second, just asthe left-behind are affected by the resources the migrant accumulates in thedestination, so they may be affected by the context in which the migrant lives.Migrants to a community like Boulder may be able to bring their relatives up northfor valuable surgeries, while migrants exposed to the wonders of cigarette smokeor drugs may bring these habits back to the fold.

5) Finally, all of this, the resources, the destination context, and the connectionsbetween origin and destination are determined by the structural context of themigration process. The awkward legal conditions of migration expose migrants to agreat many health risk behaviors as well as some, but not many, health protectivefactors. The trip itself might expose them to injuries or violence, to specificcommunicable diseases like tuberculosis, or to risk factors for chronic disease.Insecure legal status on arrival may expose the migrant to numerous risks, mostnotable an avoidance of any hospital or clinic.

And so for many conditions, we are left with a real paradox. Migrants may comefrom socially disadvantaged settings with better health than either the typicalAmerican or those they left behind. Over time, this health advantage may beeroded both due to the structural risks of migration and due to the assimilation ofnegative health behaviors common in this society. Those we might associate withgreater levels of disadvantage, say those who are living in segregated areas, mayin fact be protected by the so-called Barrio health advantage.

So migration can bebad for your health, but perhaps not as bad you think, not inthe way you think, and not in the conditions you might expect it to be bad..

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Given the potential benefits and risks of migration, we might try to movebeyond a blanket statement like migration is bad for your health andinstead look to identify the specific structural conditions could lead

migrants to experience poorer health conditions than either their originor host communities.

This is important in the context of HIV/AIDS. Given that migrants fromMexico come from a nation and typically from communities withextraordinarily low rates of HIV/AIDS; that they may be moving to ethnicenclaves with relatively low HIV prevalence; and that their communitiesmay further protect their health, under what conditions should we expect

migrants to be at widespread risk of HIV/AIDS?

One answer, of course, is that such scenarios should be relativelyuncommon.

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But we can start to piece together a risk profile. First, there arescenarios in which migrants fall into a political and oftenphysical vacuum, for instance as trafficked individuals orbonded workers. Though thankfully these scenarios are alsosomewhat uncommon at the population level.


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On a more widespread basis, we might start to look for situations inwhich migrants are exposed to the worst risks that their origin societiesand host societies have to offer, and which structural conditions might

amplify these effects.

One powerful historical example comes from the African-Americans whoattempted to settle in Liberia in the 1820s. Research by Tukufu Zuberidocuments how a population that had lost some of its natural immunityto malaria and other tropical diseases quickly and shockinglysuccumbed to the local environment, with about one-third of the settlersdying in the first year.

On a more mundane level, we can observe many examples of migrantswith high levels of metabolic risk and low rates of exercise whoencounter a sugar- and fat-rich diet in this country, with disastrousconsequences.

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Stepping away from our own context, I always return to this photo from myown fieldwork in Bangladesh. In shuttling back and forth between the ruralMatlab fieldsite and the capital Dhaka, I generally had the benefit of a

speedboat and shuttle bus, but once, during the great flood of 1998, I had theprivilege of sharing the overnight motor launch with this man, who had beenseeing his family three days a month for the past 10 years. The boat was scaryenough, and the commute and the living conditions on arrival were far worse.but at least he got to see his family once a month.

The tightening of the US border has encouraged family separation forexceedingly long periods of time. While the recession reduced the flow ofmigrants from Mexico to the US, rates of return migration remained about the

same. Given the difficulty of crossing again and the likelihood that low wagejobs would open up soon, many migrants decided to ride out the recession onthis side of the border.

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The recession also further accelerated the move of undocumented migrantsto unfamiliar destinations, primarily in the midwest and deep south, as we seein this county level representation of the foreign born.

A recent study by Emilio Parrado and Chenoa Flippen of Duke University looksat the sexual behavior risks of migrants from Mexico to their own neck of thewoods, North Carolina, and begins to weave a more compelling story ofpotentialHIV/AIDS risk. The authors acknowledge many of the protectivefactors in Mexican culture and in Mexican migrant communities in particular,but note some unique contextual conditions that predispose to higherHIV/AIDS risk: migrants coming from more vulnerable and fragmentedcommunities in souhern Mexico, an unfamiliar destination area where migrants

have fewer close relations or institutions already in place; and longer spells ofhusband-wife separation.

Taken together, these factors could encourage the increased usage ofcommercial sex workers who themselves come from highly vulnerable andAIDS-affected communities. Here we start to see a plausible scenario for highlevels of HIV/AIDS risk, and one that might turn up in other parts of the US,say in parts of Colorado.

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What is critical here is how the changing structural conditions ofmigration to the US may conspire to place migrants at increasinglyhigher levels of risk, detached from the support systems that have

sustained their predecessors, and exposed to new risks of depression,sexual risk, and other adverse outcomes.

Through it all we should also remember the other side of the migrationequation, the left behind. Migrants will make many sacrifices riskytrips, difficult jobs, skipping the doctors visit in order to send as

much money as they possibly can back to their families

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Here is a result from my forthcoming paper with Bethany Everett of CU-Boulder and Rachel Silvey of the University of Toronto that looks at theimpact of childrens migration on the survival of elderly Indonesians. We

find that elders having a migrant child are only half as likely to die in afour-year followup period as those without a migrant child, an effect thatis far larger than any socioeconomic, gender, or regional healthdifferential observable in that society.

Migration is most assuredly good for their health.

This is the flip side of migrant health risks, that those risks are often theproduct of efforts to maximize the welfare of those left behind.

In other words, any clear answer to the question is migration bad for

your health will depend on whose health and under what specific

structural and contextual conditions.

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In closing, some of you may be saying, I didnt come here to learn whether

migration is bad for health. Some migrants are sick ;; they need health care,and I want to treat them in the best way possible. How does this help me?

Good question! And so allow me to close by offering some humble principlesfor action that attempt to apply the do no harm principle to the population level.

1) First, avoid ecological fallacy. Just because your patients are sick doesntmean that the population is sick. And that patient with the very scary healthrisk behaviors might not be indicative of a pattern, but the exception thatproves just how healthy a community is. In other words, collect some datawhenever possible.

2) One good way to collect data is to raise health capacity. Remember thatmany, if not most, migrant communities have numerous capabilities andresiliencies already in place that preserve their health. Dont institute

programs that weaken these capacities, for instance by building adependency or stimulating an environment of fear. Focusing on generalneeds -- like access to preventive checkups and insurance -- might bemuch more helpful than targeting diseases having uncertain cause orconsequence.

3) In such an engagement, be mindful of our ugly history. Many immigrantcommunities have been subject in the past and present to targeting asvectors of disease. In America today, migrants who could never getprenatal or emergency care are not merely offered active tuberculosistreatment, they are forced to adopt it. When you deliver infectious diseasecare in migrant communities, know that people make this association.Focus on human rights and on maximizing trust.


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4) Unusually high levels of disease, vulnerability to disease, and distrust ofhealth providers are all most likely to emerge under conditions of extremeflux, when social and political roles are uncertain, when communities arebroken apart, when basic rights are not protected. Examples in our own

society would include trafficked populations, new immigrant clustersattached to high-risk industries, areas unfamiliar with and perhaps hostileto immigrants, and of course the ever-present border town.

5) These risks are amplified when legal restrictions make clinical outreachimpossible, positive health behaviors illegal, and negative health risksnormal. Ive already mentioned the potential consequences of spousal

separation resulting from tightened borders. A more frightening scenarioinvolves an immigration regime so tight that border control agencies can nolonger perform basic disease surveillance functions. Medical expertise is

needed to address the consequences of immigration reforms for medicalpractice, health outcomes, and health security.

6) Finally, conditions of flux and legal vulnerability are amplified when vulnerablemigrant populations make contact with vulnerable host populations. This isparticularly true when migrants and hosts are positioned in competition forscarce resources, jobs, or votes, as in areas of population transition likeSouth Los Angeles. At such moments it may be both more effective andmore safe to focus on disadvantage rather than status, particularly sincenatives may fare even worse than migrants. A careful approach tomeasuring and targeting the conditions and worst consequences ofdisadvantage offers the potential for enhancing impact, promoting doctor-patient trust, and mitigating grievances between groups.


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migration and health: the challenge of causality and implications for action

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