International migration and control of communicable diseases

SW. SC;. Med. Vol. 37, No. 12, Pp. 148991499, 1993 Printed in Great Britain

0277-9536/93 56.00 + 0.00 Pergamon Press Ltd

INTERNATIONAL MIGRATION AND CONTROL COMMUNICABLE DISEASES

OF

GEORGE A. GELLERT Arizona

Department

of Health

Services,

3815 N. Black Canyon

Highway,

Phoenix,

AZ 85015, U.S.A.

Abstract-The epidemiology and policy implications of communicable disease (CD) transmission associated with international migration have received little systematic study. This is a review of clinical and epidemiological reports in search of strategies to assess and manage the impact of international migration on the transmission of CDs. The economics and demography of migration from less developed to industrialized nations is considered. Migration-related transmission should differentiate between actual transmission as opposed to geographic relocation of disease. Limitations of current screening and disease prevention strategies are discussed. Social and ecological processes through which migration can contribute to increased CD transmission are described, including placement in refugee camps, unclear legal status of migrants in recipient nations, and temporary return migration. Strategies for non-discriminatory and non-punitive control of migration-related CDs, needed changes in clinical practice, and complexities presented by CDs of long latency (such as HIV infection) are reviewed. Key words-infectious

disease,

communicable

MIGRATION AND COMMUNICABLE

disease,

DISEASES

IN HISTORY

Long before scientists had the ability to study microbes or international migration, microbes caused the movement of peoples [l-5]. In the 1840s the fungus Phytophthora infestam arrived in Ireland by ship from the Americas and destroyed a large part of the Irish potato crop, the Irish dietary staple. From 1846 to 1848 a famine occurred that resulted in approx. 1,240,OOO deaths. Emigration for the same period was 1,174,311, mostly to Canada and the United States [ 11. The settlement of south China may have been facilitated by parasitic diseases that were more endemic in the warmer south, acting to retard population shifts to new regions [l]. The Spanish colonization of the new world was aided by the spread of smallpox and measles (in Mexico the native population fell from roughly 30 million in 1519 to 3 million in 1568) [5]. By the time the conquistadors reached Peru in the 1520s smallpox was already decimating the local Incan civilization and had killed its ruler. Jesuits transmitted smallpox to the Iroquois Indians in Canada, resulting in the demise of a large native population and in the British conquest of the North American Indians [l]. Communicable disease (CD) epidemics may have even fueled the African slave trade, since shared immunities with Europeans meant that Africans made better slaves [S]. Migration and CDs have been interacting for centuries and probably millennia. The focus of this review is not on CD as a cause of migration but on the impact of international migration on the epidemiology of CDs in recipient nations. CD transmission accompanying international migration has been described and its public health implications warrant review. This discussion will focus on inter-

migration,

national workers, tourists.

immigration

immigrants, refugees, temporary foreign undocumented migrants and travelers and

ECONOMICS AND DEMOGRAPHY OF MIGRATION: BASIS AND POTENTIAL SCOPE OF THE PROBLEM

Escape from persecution and the search for greater prosperity have long fueled migration. Prior to the 20th century, migration occurred between nations that were less polarized economically, and although economic disparities have stimulated migration, few earlier civilizations could be described by contemporary extremes of poverty, affluence and health status. Two-thirds of the current global population live in less developed countries (LDCs) [6]. While the doubling of world population from 1 to 2 billion people required 130 years, an increase from the current 5-6 billion will occur in just 10 years. In 1945,40% of the world’s population lived in developed nations, but by 2000 this figure will drop to 20%; by 2025 95% of all projected increases in world population will occur in LDCs [6]. Poverty is reflected in international health comparisons of infant mortality rates, age-adjusted incidence of diseases, and life expectancy [7710]. Economic polarization of an expanding world population may contribute to increased migration. Environmental deterioration associated with increasing industrialization (desertification, rising sea levels from global warming, deforestation) may exacerbate economic and demographic pressures to migrate, giving rise to ecological refugees. Specific patterns of migration, or migration streams, will shape opportunities for CD transmission among susceptible recipient populations. In 1988, 84% of 643,000 immigrants to the U.S. originated in Latin America or Southeast Asia [1 I]. There

1489

GEORGEA.

1490 Table

I. Analysis

Communicable industrialized Result:

of migration-related

diseases

are

more

ready

detection

nations

commonly

in less developed

more

have

in the

of epidemiologic

disease transmission

public

health

(diagnostic,

accurate

measurement increases

and source

of transmission.

relative

noise”

caused

by other

wth

less potential

for commumcable

and industrialized

population

surveillance)

nations infrastructure

of

2. Factors

of individual

Movement of

epidemic

and

endemic

communicable

diseases

occurrmg

that occur infrequently

in developed

natlons

facilitates

determination

of route

ease of attributabihty.

Table

High

and

misclassification.

dwases

are no figures on undocumented immigrants, but the U.S. Immigration and Naturalization Service (INS) apprehended over 1 million deportable migrants in the same year [ Ill. The most populous U.S. states are evolving towards “minority majorities” comprised heavily of immigrants. The Eurocentric pattern of Western immigration declined since the 1960s [12], while emigration from Asia, Africa and Latin America increased (e.g. though the total number of visas granted climbed dramatically, 117,090 U.S. visas were granted to Europeans in 1965 and only 44,839 were in 1990). As Western populations are aging, youthful LDC immigrants have become essential to the workforces of many industrialized economies. CDs are leading causes of morbidity and mortality in LDCs and as developing to developed nation migration streams increase in number and magnitude of flow, CD transmission may increase. The introduction of CDs that are endemic in the developing world to industrialized nations has public health implications. Tuberculosis eradication in the U.S., for example, has been limited partly by an inability to conduct surveillance and institute treatment of Southeast Asian and Latin American immigrants. In Southeast Asia, the Middle East, and Africa the prevalence of hepatitis B virus infection ranges from 5 to 15%, and is a major cause of morbidity and mortality from acute and chronic hepatitis, cirrhosis, and primary hepatocellular carcinoma [13-151. Hepatitis B is hyperendemic among Asian and Pacific Islander migrants, and over 150,000 infants are born annually to women who have immigrated to the U.S. from endemic areas of the world [ 16, 171. Screening selected pregnant women has failed to control disease, and universal childhood immunization has become a strategy for eliminating transmission in the U.S. [18]. In 1991, epidemic cholera appeared in the Western hemisphere for the first time this century. The first cases were reported in Peru and disease subsequently spread, in part possibly through migration-associated contamination of food and water, to Ecuador, Colombia, Chile,

Crowding

less developed

nations.

of incidence

Breakdown

between reporting

trends

“background

less competing

Magnitude Result:

commumcable

detectable

nations.

Developed Result:

more

GELLERT

populations

in relief

and

rates of malnutrition

contributing

to increased

access to the existing into

refugee

zones with camps

increase

health

different

Guatemala and Mexico of migration-related CD will continue to be influenced by increasing LDC poverty, population growth and migration.

disease morbidity

reduces disease control

ecologies

opportunities

10 communicable

MIGRATION AND DISEASE OCCURRENCE

International migration that involves the annual movement of tens of millions of people has become a norm of modern societies, yet the public health and policy implications of migration-related disease have been little assessed. The complexity of the problem requires a multidisciplinary collaboration between health, behavioral and social scientists, drawing from epidemiology and public health, clinical medicine, demography and economics. A political liability exists for researchers because of precedents where data were used punitively to discriminate, place blame or erect immigration barriers. Variability in disease onset, whether disease is acute or chronic, and rapidity of progression under conditions of migration present problems. Most CDs manifest acutely within the first generation from LDCs where health infrastructure is deficient. Detection and attributability of disease in nations with similar disease epidemiology and levels of economic development is difficult. Analysis of transmission occurring with migration from LDCs to developed nations is facilitated by several characteristics (Table I). Factors that exacerbate CD morbidity and mortality among migrants, particularly in LDC to developed nation migration, are described in Table 2 [23]. In the 1980s the diversity of infectious agents and highly varied migration streams produced many patterns of migration-related CD. A broad sampling is presented in Table 3 [2&75]. The variability of transmission patterns would require that diverse detection, treatment and prevention strategies be integrated with international immigration rules. Disease prevention and management would have to be related to a uniformized international set of exit and entry

communicable

microbial

El Salvador,

EVALUATING

infrastructure

leads to increased

susceptibility

Brazil, Panama,

[ 19-2 11. The epidemiology

exposes susceptibles

and mortality and treatment with

for disease transmission

diseases.

low

among

migrants

capabilities.

immunity

lo new agents

International migration and control of communicable diseases Table 3. Sample Disease/agent

patterns of

communicable

Nation/region

disease associated

with international Recipient

of origin

1491 migration

nation

Burma Kampuchea Afghanistan Ethiopia India Southeast Asia

Britain (241 Thailand [25.26] Pakistan [27] Israel [28,29], Sudan [30] Kuwait [31] Australia [32], U.S. (CA) (331

Vietnam, Laos and Cambodia Vietnam Nicaragua Afghanistan Ethiopia

U.S. (TX, CA, MA, CT, WA) [3&38] Hong Kong [39], Phillipines [40] Costa Rica [4l] U.S. (CA) 1421 U.S. (CA) [42], Sudan [30]

Trypanosomiasis

Nicaragua El Salvador

U.S. [43] U.S. [44]

Tuberculosis

Ethiopia Southeast,

Malaria

Intestinal

Typhoid

Infection

Fever

Liver Fluke Infection

Latin America Sri Lanka Afghanistan

Israel [29], U.S. [45] Canada 146,471, Britain [48] Australia (49, 501, U.S. (NY, PA, CA) [Sl-541 U.S. (CA) [55,56] Middle East [57] Pakistan [27]

Ethiopia

Israel [29]

Thailand Southeast

Measles

Ethiopia

Syphilis

Ethiopia Southeast

HTLV- I Hepatitis

East and South Asia

Asia

Sudan [30] Asia

Ethiopia Southeast

U.S. [45], Israel [62] U.S. 1631 Bolivia (64,651

Japan B

Kuwait [58] U.S. [59-61]

Asia

Israel [29] U.S. [16, 17)

Strongyloidiasis

Southeast

Asia

Australia

Trichinosis

Southeast

Asia

U.S. [68]

Hookworm

Southeast

Asia

Japan (691

Schistosomiasis

Surinam Cambodia

Filiaria

Haiti

Leprosy

Southeast

Rabies

Mexico, Laos and Phillipines

U.S. [75]

Cholera

Peru

Ecuador

Netherlands [70] Thailand [7l] U.S. (FL) [72] Asia

rules. The strategic and technical integration of disease control initiatives with social and political constraints is an unrecognized field of public health. An international regime for migration [12, 761 would be difficult to coordinate with a uniform and universally applicable set of disease precautions because of the large number of pathogens affecting migrants. The diversity of migrant groups, geographic origins and destinations also resists straightforward formulation of disease control strategies and public health policies. SECONDARY TRANSMJSSJON DJSEASE RELOCATJON

[66], U.S. [67]

AND

Risk of secondary CD transmission to recipient populations from migrants should be differentiated from geographic relocation of CD cases. Migration that introduces CD pathogens to unexposed recipient populations represents a threat to local public health only when the risk of transmission to new susceptibles is high, i.e. where agent, host and vector where necessary occur with opportunity for exposure. For CDs with little or no risk of transmission, the recip-

U.S. (TN, MN, CA, HI) [6l, 73-741

[20] Columbia

(201

ient nation is only accepting an economic burden to treat CDs in new citizens. A disease-by-disease assessment of the life cycles of imported pathogens and the potential for secondary transmission in specific settings would aid disease control planning. International migration for the majority of CDs implies only relocation of infected individuals. Malaria infection among Thai migrants to Kuwait, for example, is a relocated disease burden with limited risk of secondary transmission [31]. Outbreaks of migrationrelated malaria have occurred, however, where the mosquito vector is plentiful. Since 1950, 21 outbreaks of introduced malaria, all caused by Plasmodium viuax, have been identified in the U.S. [77]-14 of which have occurred in California. Latin0 temporary workers have imported malaria into California where outbreaks and secondary transmission to local residents have occurred [78, 791. Other clusters of introduced malaria in U.S. border areas likely have gone unnoticed because a diagnosis of malaria may not have been made in symptomatic patients with no travel history, and because migrant workers have limited access to medical care [77].

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GEORGE

Concerning other modes of transmission, sexually transmitted diseases (STDs) do not require a nonhuman vector and migrants present a direct transmission risk if not endemic in the recipient population. Transfusion has emerged as a concern. Until recently, Chagas’ disease was relocated from Latin America to the U.S.. since exposure to the parasite’s reduviid insect vector is uncommon north of Mexico. Chagas’ disease is a major cause of morbidity and death in Latin America, where lo-12 million people are estimated to be infected with Tryanosomu uuzi [80]. In 1984, 0.552 million Central Americans resided in the U.S. [81]. T. cruzi has entered the U.S. blood supply from blood donated by these immigrants [43,44.82], and secondary (nosocomial) transmission has occurred [83-851. Fecal-oral transmission of intestinal pathogens do not present recipient nations with transmission risk from migration unless an immigrant food handler or traveler transmits disease through poor personal hygiene or importation of contaminated food items. Sanitary practices and infrastructure in industrialized nations usually prevent secondary transmission of most intestinal pathogens. For respiratory transmission, tuberculosis carries risk for recipient populations but is mostly relocated disease. From 1986.-89, 22% of reported cases of tuberculosis in the U.S. occurred in the foreign-born population 1861. In 1989 a U.S. plan for eliminating tuberculosis by 2010 targets immigrants since the U.S. rate was 9.5 per 100,000 population but 124 per 100,000 for the foreign-born [86]. Perinatal transmission has been a major concern. for example in hepatitis B and HIV control, which often involve both an economic burden for treatment of relocated infants as well as elevated risk of secondary transmission IMPLICATIONS FOR DISEASE CONTROL

Reports of CD associated with international migration vary greatly in methods and informativeness. Many studies describe small series of migrants, anecdotal case reports, or nonrepresentative samples, and few offer data on controls or disease incidence in non-migrant populations of the nation of origin. Duration of study is often limited or episodic and magnitude of secondary transmission is not assessed. Caution in interpreting the literature is needed. In Britain, for example, an average of 1843 cases of malaria were reported annually from 1979 to 1989 [24]. Cases were not, however, entirely migration-related, many were acquired by workers near airports bitten by infected mosquitos imported on flights from endemic areas. Increased malaria incidence among Afghan refugees in Pakistan suggests the import of a heavy burden of malaria infection from Afghanistan. The refugees, however, were found more susceptible to malaria than local Pakistanis, and infection likely occurred after migration [27].

A.

GELLERT

Relocated CD as opposed to secondary transmission offers distinct problems for surveillance, preventive planning and disease management. Improved access to data and cooperative population-based studies with Western epidemiological centers may offer public health officials a sense of the endemicity of CDs in nations of migrant origin. Heightened local surveillance among migrants in recipient nations should be considered when preliminary data suggest a heavy burden of migration-related CD. The interpretation of these data should occur in an atmosphere that is non-punitive, with clear public health objectives stated and assurances of confidentiality and non-discrimination. When CD is relocated. efforts to limit transmission are usually directed at therapeutic measures to achieve disease cure. If infection is acquired during migration. efforts should be directed at disease prevention as well as cure. Selective serological testing of refugees for CD is increasing, but the accuracy of testing has been a concern. The Australian government, for example, conducts overseas screening of refugees, but at times in excess of 50% of refugees landing in Sydney with a positive serology for syphilis had negative results when screened overseas [32]. Close monitoring of the quality of overseas screening is needed. If overseas screening results in a high rate of false negatives, recipient and migrant populations arc threatened by an undetected and therefore unmanageable risk of disease. When a high f&se positive rate occurs, migrants may be denied entry and asylum from persecution, prospects of being reunited with family, and economic opportunities. Immigration officials require technical consultation to assess the LDC-specific epidemiology and biology, life cycle and clinical expression of CD pathogens. In malaria control. for example. an assessment of whether the mosquito vector can propagate in the recipient ecosystem is required. In Kuwait, malaria transmission rarely occurs and risk is negligible. Increases in malaria among Indian migrants to Kuwait therefore suggests that control strategies should target the treatment of imported malaria, and not the institution of restrictions on migl.ation [31]. Infection with T. cm5 is lifelong, and individuals may develop Chagas’ disease decades after emigrating. Of 205 Central Americans studied in Washington, D.C., 5% were infected with 7’. cruzi (441, and routine serologic testing at entry may be indicated for these groups. In view of its limited communicability. a more efficient policy may involve deferral or selective screening of blood donations from immigrants of Chagas’-endemic Latin American nations [43.44,82]. SPECIAL MIGRANT POPULATIONS (i) Rejkgees

Thirty million refugees and displaced people have been created by war, civil strife and persecution [87]. In 1989 over I4 million refugees were estimated to

International migration and control of communicable diseases need protection and assistance [Ml; 18 million were by 1991 and 30 million people were displaced within their own countries (and technically not considered refugees) [89]. Refugee migration often occurs from one LDC to another, and both nations have low per capita income (e.g. $400) and poor health indicators (e.g. infant mortality rate of 120/1000 live births) [88,90]. Mortality in refugees has exceeded expectations by up to 60-fold. Much of the excess mortality is preventable through improved planning and policy. Most studies of CD in refugee populations do not differentiate whether individuals were infected in the community of origin or the refugee camp. CD risk is not mitigated by the fact that in 1987 fewer than 15% of refugees were resettled [90]. Refugee camps often have inadequate sanitation and nutritional support, contaminated water supplies and severe overcrowding [40,88], conditions that are ideal for CD transmission. Infectious causes of death among refugees include gastroenteric and acute lower respiratory tract infections, as seen in nations of origin [88]. Higher incidence and case fatality rates, however, differentiate refugee populations from those in nations of origin [88]. Measles and malaria have been serious problems, and less frequently meningitis, cholera, typhus, relapsing fever, tuberculosis, tetanus and hepatitis [88]. Policies to prevent importation of refugee-related disease can be misdirected. Extensive CD screening of refugees has not been logistically or politically feasible. Disease promoting conditions in refugee camps, however, can be improved rapidly to reduce excess mortality and risk of secondary transmission in new countries. Excess mortality can be reduced by providing clean water and food rations with adequate calories, protein and essential micronutrients, by immunizing children, and through early malaria detection and chemoprophylaxis [88]. Establishing curative programs (e.g. standard treatment protocols, micronutrient fortification, oral rehydration therapy), and nutritional surveillance and health information systems can reduce CDs, as can partial integration of refugees into localities to lessen crowding in closed refugee camps [88]. (ii) Temporary foreign workers

It is valuable to differentiate true immigrants from temporary foreign workers. Of 175 cases of paralytic poliomyelitis imported to industrialized countries between 1975 and 1984, for example, 55% occurred in foreign workers and only 6% in immigrants [91]. Polio is vaccine-preventable and these data suggest a role for routine immunization of migrant workers from endemic regions. Malaria control in the U.S. is also hampered by the socioeconomic and legal status of temporary foreign workers. Reduction of risk for malaria in migrant workers will require improved disease surveillance, better access to medical care and early detection of malaria cases [78]. The distinction between temporary foreign workers and undocu-

1493

mented migrants is often fluid. Temporary foreign workers may become undocumented migrants within recipient nations. Despite the short duration of visits by temporary foreign workers, proactive disease control planning should consider workers in efforts to prevent CD. (iii) Undocumented migrants

The legal status of migrants is relevant to CD control, since it has been problematic for one government agency to pursue immigration control while another encourages undocumented migrants to utilize local health services. The effect of such incongruous policy objectives is evident in a resurgence of measles in the U.S. Underutilization of health care services among undocumented Latin0 migrants undermines measles control. Hispanic two-year olds in California are 50% less likely to be up to date on measles immunization than white infants. Lower rates of immunization may be attributable to underutilization and low awareness of health care availability, but social factors such as fear of exposing undocumented status are prominent [92]. At a measles immunization campaign targeted at Latinos in Los Angeles, children in families with Mexicanborn parent and child were 15 times more likely to underutilize health care and 43 times more likely to be unimmunized than those in families with U.S.born parent and child [93]. Improved local outreach to undocumented migrants and resolution of ambiguous, conflicting government policies will improve CD control. fivv)Adopted children Over 8000 foreign-born children are adopted by U.S. citizens annually and this figure is increasing. A majority of these children are from LDCs, and deficient immunization (37%) intestinal infections (29%) and chronic hepatitis B carriage have been reported [94]. Within one month of arrival, 49% of children reported a CD. The U.S. Centers for Disease Control has recommended that adoptees from nations where hepatitis B infection is endemic should be screened for hepatitis B surface antigen [16], and if positive, family members should be vaccinated [95]. Care for children adopted from LDCs should focus on CD screening and follow-up. (v) Return migrants Temporary return migration exerts a strong cultural and emotional pull on many immigrant groups, and may contribute to migration-related CD. Almost 2% of Asian immigrants infected with tuberculosis over a five year period in West Ham, Britain acquired infection from return visits to Asia [96]. Citizens may travel back to LDCs and acquire new and re-infection. With CD control practices based on early life in LDCs, immigrants may view CD preventive hygiene from the less fastidious perspective of an

GEORGEA. GELLERI

1494

endemic region. Health education on CDs for return visitors to endemic regions may prevent infections. (vi) Travelers and tourists Travel from industrialized nations to and from LDCs may expose new susceptibles and elevate risk for CDs. In 1988, 14.7 million non-immigrants visited the U.S., of which 73% were tourists and 16% business travelers [ll]. Travel and tourism are the world’s largest industries, employing I12 million people and comprising 5.5% of global gross national product [97]. As tourism and international business travel in LDCs increase, so does risk of CD transmission. Seven million American civilians annually travel to nations with endemic malaria transmission [98]. In 1990 it was estimated that 2.1 billion people live in malarious areas of the world and that 270 million people newly develop malaria each year [99]. A threefold increase in malaria importation by U.S. travelers has been reported since 1980, with increases in the U.K. as well [loo, IOI]. During 1980-88, 1534 cases of imported P. falciparum malaria were reported among US civilians. Schistosomiasis and dengue have been imported by U.S. travelers [102, 1031. Travelers have been protected against vaccine-preventable CDs through pre-departure immunization. Hepatitis B has recently been added to the list of immunizations for persons spending greater than 6 months in endemic areas [l8]. Improved CD preventive education for travelers may be required to keep pace with growth in world travel. Disease control policies should be shaped to the uniqueness and heterogeneity of today’s migrant population. CLINICAL CARE FOR MIGRANTS WITH COMMUNICABLE DISEASE

As LDC migration increases, Western health care providers should strengthen competencies in diagnosis and treatment of CDs prevalent in LDCs [104, 1051. Physicians should be aware of elevated CD risk among these groups. Office education for return migrants and travelers can reduce risk. Clinicians will have to suspect unusual CDs. such as cholera or malaria. Diagnosis and treatment of cholera must be rapid and aggressive because of the dramatic rate and volume of dehydration. In view of secondary malaria transmission in California and Florida [78,79], the CDC has recommended that malaria be included in the differential diagnosis of any patient with a fever of unknown origin [79]. Taenia solium infection is endemic in Latin American LDCs with high emigration, and U.S. incidence of cerebral cysticercosis is increasing [104]. Human clonorchiasis is endemic in Asia, where the raw fish is consumed. Over 20 million Chinese have clonorchiasis [106]. These liver flukes are the most frequent cause of cholangiocarcinoma in East Asia, affecting the more than 500,000 Southeast Asians who have immigrated to the U.S. since 1975 (Asians are the most rapidly growing group in the

U.S.). Up to 26% of Asian immigrant groups have been reported infected and the clinical presentation and long term sequelae of infection are little known to many Western physicians [59]. Leprosy affects over I2 million people worldwide [ 1071, and reported cases have increased in the U.S. as a result of immigration. From 1949 to 1968, when the ratio of U.S.-born to foreign-born cases was I : 1 [log], the ratio is now 1 : 3. and > 75% occur in the foreign-born. Schistosomiasis is endemic in 74 nations in Africa, South America, Asia and the Caribbean [109]. As travel to these regions increases physicians should be aware of the presentation, diagnosis and treatment of this disease [102]. Increased LDC migration challenges Western health care providers to overcome language barriers and cultural differences in perception of disease, communication style, illness experience, health beliefs and care seeking behavior. In Southern California over 20 ethnic groups, many from LDCs, have settled over the last three decades. Migration streams will continue to multiply from coastal gateways such as Los Angeles, Miami and New York to include many regions throughout the U.S. Clinicians require current data on the identity of new immigrant groups in their communities, and endemic CD risk. Merging migration and CD epidemiological data, perhaps within the local public health agency, may be useful. Strengthening CD surveillance among migrants will improve the ability of local physicians to rapidly and accurately recognize and manage new CDs. A community risk profile of migration-related CD would facilitate proactive public health and preventive programs. MIGRATION AND COMMUNICABLE LONG LATENCY

DISEASES OF

Control of infections with long latency is complicated among migrants because early diagnosis occurs infrequently. Of 1835 cases of leprosy reported in the U.S. from 1971 to 1981, only 25% of imported cases were known to have had leprosy at migration. Although most of the remaining 75% were detected within 12 months of entry, cases continued to be reported IO years after entry [ 1051. With the acquired immune deficiency syndrome (AIDS) pandemic, the rights of non-citizens to enter and remain in countries has involved foreign policy and international as well as domestic health issues [I 10, 11 I]. To secure national borders against an “invasion” of human immunodeficiency virus (HIV) infected individuals, up to 50 nations have introduced border restrictions or required HIV antibody testing of immigrants and nonimmigrant residents [I 12. 1131. In 1987 the U.S. Congress added AIDS to the list of “dangerous contagious diseases” that deems a person inadmissible. Although technically excludable under law, seven million tourists, students and other visitors seeking temporary admission each year have not been

International migration and control of communicable diseases tested routinely for HIV antibodies. The list of “communicable diseases” is intended to include only diseases that are casually transmissible. In 1990 the U.S. required HIV antibody testing of >500,000 immigrants and refugees, and >2.5 million persons living in the U.S. had to be tested to qualify for legal residence, causing the U.S. to have the broadest policy of testing and excluding foreigners in the world [114]. U.S. policy refuses admission to HIV infected refugees except in extraordinary circumstances, where the refugee can demonstrate that admission would not endanger the public health, that the risk of spreading infection was minimal, and that there would be no cost incurred by government. The policy was not based on scientific data indicating secondary HIV risk from migration, and one study merging demographic and AIDS prevalence data to analyze the contribution of international population movements to AIDS spread found none [I 151. In 1991. a new U.S. list of CDs of public health significance was proposed to include only active tuberculosis but was never adopted [ 1161. HIV infected individuals could have been allowed to remain in the U.S. or expelled to nations less capable of contending with the disease. Applicants for legalization were often long-term residents, many of whom fled persecution or developed strong familial ties in the U.S., and could have been infected in the U.S. Individuals denied legal status were likely to remain in the subculture that immigration reform was intended to eliminate, concealing their presence in the U.S. when guidance and care are most needed [117]. Fear of apprehension and deportation acts to discourage HIV/AIDS care seeking. The U.S. policy endangers public health by obstructing HIV education on methods of disease prevention in this population. As most legalization applicants are from LDCs unable to cope with the HIV epidemic, deporting HIV infected individuals would further burden national health systems and possibly introduce HIV to areas reporting less AIDS cases [119]. Deported individuals may be deprived of treatment options or persecuted because of their infected status [ 1171. Testing is prohibitively expensive in nations from which most immigration streams to the U.S. originate, and its cost would exceed the annual per capita health budget of many LDCs. The diversion of limited testing facilities to immigration-related testing is an inappropriate allocation of scarce resources that should be used to screen individuals involved in high-risk behaviors or to meet other health care needs [ 1171. The World Health Organization concluded that HIV spread could not be halted by testing travelers, including immigrants and refugees, and the U.S. Presidential Commission on the HIV Epidemic concurred [118, 1191. Testing applicants for immigrant visas each year is a misguided enterprise that does not diminish the spread of HIV (the U.S. is already an area of high prevalence with a reservoir of over 1 million infected individuals). HIV immigration SSM

37/12--G

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screening generates unfounded suspicion of foreigners, encumbers travel and commerce, and obstructs international exchange and communication [117]. Such policy is unlikely to reduce the reservoir of HIV infection in the world, and without provisions for education and counseling, the only potential global effect of restrictions on international travel may be to cause a marginal shift in the geographic distribution of infection [I 141. The economic impact of HIV infection among immigrants to Canada was found comparable to the costs of coronary heart disease, suggesting that a focus only on the costs associated with HIV infection may be arbitrary [ 1201. Yet screening foreigners is politically popular and the U.S. has not been alone in pursuing some variation of it. The policy undermines national and international efforts to combat AIDS. A more effective and humane policy is to grant waivers to infected legalization candidates, and assure participation in counseling and prevention programs [ 1171. CONCLUSIONS

AND FUTURE ISSUES

The present nature and magnitude of migrationrelated CD transmission does not indicate a general risk to the public health of industrialized nations. A number of CDs (such as tuberculosis, hepatitis B and measles) present specific ongoing public health problems, but most CDs associated with international migration in recent decades have been relocated and do not threaten the health of recipient populations. The future scope of the problem, however, may increase considerably in the face of rapidly changing global demography and expanding migration. Emerging potential issues include CDs among > 500,000 Gulf war military personnel [121-1231, or among 1.5-2 million Kurdish refugees, a prospective migrant population. Excess mortality of about 1400% has been reported in Kurdish refugees due primarily to infectious diarrhea [ 1241. The allied effort to protect the Iraqi Kurds overcame national sovereignty issues that had obstructed international aid to internally displaced populations. It remains to be seen whether this precedent will impact on the > 30 million internally displaced persons worldwide. Cholera transmission in this hemisphere may be exacerbated by migration. Migration in South America can propagate transmission (an estimated 60,000 border crossings occur daily between Peru and Ecuador). In 1991, 16 epidemic associated Vibrio cholerae infections had been reported in the U.S. [21]. Although risk of cholera to tourists is very low [125], in view of the heavy travel between North and South America, additional imported cases among travelers are to be expected. No cases imported since 1961 have resulted in secondary transmission [125], however, U.S.-Mexico border jurisdictions have improved cholera surveillance and education [126]. Migrationrelated CDs may result from the proposed North American trade pact, through which biological

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contacts between Mexican, U.S. and Canadian populations will increase. Mass migrations may emerge from sociopolitical change in Eurasia. Liberalization of immigration policies in the former Soviet Union and Eastern Europe may profoundly affect international population movements. Hepatitis B in the Commonwealth of Independent States (CIS) is endemic, partly attributable to repeated nosocomial use of unsterile hypodermic syringes [127]. Between 1974 and 1987 hepatitis B incidence in the U.S.S.R. increased from 13.5 to 42.0 per 100,000, and doubled from 1980 to 1987 [ 1281. Numerous migration streams could eventually flow from the CIS to the West. From 1985 to 1989-a five year period preceding any significant liberalization of Soviet, Eastern European or U.S. immigration policy-over 145,000 immigrants and refugees entered the U.S. from the U.S.S.R., Romania, Czechoslovakia and Hungary [129]. In resisting politically expedient but epidemiologically meaningless policies, it will be important to recall (as with HIV screening and other restrictive strategies targeted at migrants) that the U.S. already has an estimated l-1.25 million person reservoir of hepatitis B. On a global scale the states of the former Soviet Union represent the largest remaining uninfected population at risk for HIV infection. International mobility (including tourism and commercial exchanges) to and from the CIS will increase dramatically and with them the risk of a Eurasian HIV/AIDS epidemic. Concern about HIV importation .from industrialized nations should be addressed by providing international health assistance to newly emerged Eurasian nations for capacity-building in HIV/AIDS education and prevention [ 1301. There has been little systematic study of the interrelationship between migration and CD transmission. Public health programs and policies driven by epidemiology remain underdeveloped. Greater attention must be focused on monitoring risk factors and changing CD epidemiology in situations of mass migration. Governmental, nongovernmental and international agencies concerned with migration should establish collaborative local, national and international epidemiologic and migration databases for ethnically-specific CD surveillance. Policy must address the epidemiological and cultural uniqueness and heterogeneity of emigrating groups. Enhancing incentives and eliminating policy inconsistencies in community-based disease control efforts, and voluntary migrant participation, will be essential. Technical strengths and weaknesses of screening methodologies need to be assessed for how they reflect policy and shape the behavior of target populations. Increasing health interdependence among nations [ 1311 and a convergence in the needs of international and domestic health sectors [132], argue for reducing CD incidence in LDCs (at the point of origin) as the most cost-effective and humane disease control strategy. Efforts to improve child survival through develop-

ment assistance, immunization and capacity-building of public health infrastructure within LDCs should focus on donor self-interest as well as philanthropy [132]. Many LDCs have made great progress in combating CDs-noncommunicable diseases are responsible for 70-80% of deaths in developed nations and 40% in LDCs [133]. Migration-related CD transmission poses new conceptual and practice challenges to clinicians, epidemiologists and migration scholars. Collaborative working relationships among the latter, in partnership with enlightened government leadership, can yield scientifically legitimate policies and equitable strategies to control CD transmission associated with international migration.

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