Every day an estimated 2 million people cross an international boundary. Many of these people are travelers on short visits. Others are immigrants, either refugees or voluntary migrants. Some migrants never cross national borders but are displaced within their own nations. As of 2016 there were at least 64 million internally displaced persons (IDPs) worldwide, the highest number since the United Nations (UN) began counting in 1950. IDPs typically migrate or are forced to move because of war, ecological disaster, disease, or economic collapse. The UN estimates that 20 people are driven from their home by violence or persecution every minute.

The increasing movement of people across the globe plays a significant role in the spread of disease. Since antiquity health hazards have moved across long distances through movement of people. Travel, trade, exploration, and war forged nations but also spread disease. Travel by horse or on foot was slow, serving as a limited barrier to the transport of infectious disease. Those who fell ill often died or were no longer ill by the time they reached other population centers. Ships spread diseases faster, as a disease could linger on a ship for months, infecting whole crews. In addition, the large cargo load of ships posed a unique disease risk. In the case of the Black Death (plague), rats aboard cargo ships likely hosted fleas responsible for spreading plague throughout Asia, the Middle East, and Europe. In the modern era, the spread of air travel and its reduced costs have greatly increased the number of travelers and have heightened the risk of disease. Air travel permits infected people and diseases to reach new populations, often in distant locations, within hours.

Immigration raises many of the same disease issues as voluntary travel. However, immigrants also have unique health needs. Some immigrant populations come from areas with parasites or other infectious diseases that are endemic to their homeland but have been eliminated in the industrialized world. Immigrants may not have had access to routine health care in their home countries. Providing effective health care to immigrant groups requires training health care professionals to recognize the health needs of diverse immigrant groups.

Cholera, dysentery, typhoid, tuberculosis, human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS), and malaria are only a few of the infectious diseases that migration and immigration have helped to spread. Illnesses that have been largely eliminated from some areas, such as malaria or tuberculosis, can be reintroduced by migrants. Such cases of disease are labeled imported cases. For example, in the 2010s the World Health Organization (WHO) became concerned that refugees from the Boko Haram insurgency in Nigeria may spread polio to other Lake Chad basin countries and the rest of sub-Saharan Africa. The instability that creates refugees also hampers vaccination and other public health efforts.

Cholera, dysentery, and typhoid are major killers that are spread by poor sanitation. Densely packed refugee camps with improper sanitation and poor hygienic conditions foster outbreaks of infectious disease. Carelessness can also be deadly. In 2016 the UN accepted responsibility for spreading cholera in Haiti via peacekeepers from Nepal who were providing aid after a 2010 earthquake. Nepal had a cholera epidemic at the time, and human waste from the UN base leaked into the Meille River. The Haitian epidemic killed at least 10,000 people and sickened hundreds of thousands more.

The construction of latrines and treatment of wastewater has helped reduce some incidences of infectious disease. Such measures are not always possible at severely underre-sourced, overcrowded, and hastily constructed refugee camps. Food shortages and malnutrition in refugee and IDP camps also contribute to the spread of disease.

In Salerno, Italy, immigrants rescued from the Mediterranean Sea are place in quarantine to try to prevent the spread of disease. © Carlo Hermann/KONTROLAB/LightRocket/Getty Images © Carlo Hermann/KONTROLAB/LightRocket/Getty Images

It is difficult to measure the scope and distribution of infectious disease spread by immigrants because of reporting difficulties. Health care systems in some countries, including developing nations that have received large numbers of refugees from neighboring nations, are too inadequate to correctly identify diseases and complete the necessary procedures for effective reporting. However, the US Centers for Disease Control (CDC) and WHO have helped identify areas of concern.

Haiti has sent large numbers of economic and political refugees to the United States and to other Caribbean nations. In 2006 the Jamaican Health Ministry reported that there was a link between Haitian immigrants and a recent outbreak of malaria in Jamaica. Deoxyribonucleic acid (DNA) testing by the CDC tied an outbreak in Kingston to a single source consistent with the Falciparum malaria parasite found in Haiti. At least 302 Jamaicans were infected. The government conducted an island-wide surveillance of breeding sites for the Anopheles (malaria-spreading) mosquito and destroyed about 450 Anopheles breeding sites in 256 communities.

Tuberculosis, an infectious disease that in some forms is resistant to treatment, is spread through air droplets expelled when infected people cough, sneeze, speak, or sing. It had largely been eliminated from some nations, notably the United States and the United Kingdom, until Page 474  |  Top of Articleimmigration brought it back. In 2001 61.4 percent of all tuberculosis cases in the Netherlands occurred among foreign citizens. Tuberculosis transmission during air travel has been documented by WHO.

Varicella, the chickenpox virus, is yet another disease that can be spread by immigrants. In tropical countries varicella does not generally infect in early childhood as it does in temperate zones. In the tropics infections typically occur in the late teens and 20s, meaning immigrants from those countries do not have the same high level of immunity to chickenpox as do young adults who grew up in temperate countries.

The International Health Regulations (IHR), a WHO-designed legal instrument, aims to provide maximum security against the international spread of diseases with a minimum interference with world traffic. The first IHR, approved in 1969, only targeted cholera, yellow fever, and plague. The rise of globalization prompted a revised IHR, which took effect in 2007 and is binding to 196 countries. Among its many measures, the IHR establishes a single code of procedures and practices for routine public health measures at international airports and ports and some ground crossings. The regulations focus on ensuring early detection, confirmation, investigation, and rapid response for any emergencies of international concern.

Infectious diseases do not recognize borders. Accordingly, nations need to improve their medical surveillance to safeguard the health of their citizens. The IHR is one step in this direction. Screening and immunization programs would protect the health of immigrants and established residents. Canadian medical researchers have recommended that family doctors should ask young adult immigrants and refugees whether they have ever had chickenpox, test those who answer in the negative, and offer to vaccinate those who are susceptible to the disease.

For many years Somalia had an HIV prevalence rate of about 1 percent, which was lower than that of many African countries. After much cross-border movement of HIV-infected refugees from Ethiopia, however, the HIV infection rates in Somalia subsequently increased. Condoms are generally unavailable in Somalia, and there is a lack of adequate health care. Other African nations have experienced similar patterns of disease progression with HIV. Eleven African nations have HIV prevalence rates over 13 percent.

Political issues are also affecting international public health. Taiwan lacks full membership in WHO because of a historically strained relationship with mainland China. The island state has had more success than any other East Asian country in fighting H5N1, or avian influenza. Nevertheless, WHO has refused Taiwan's applications to attend avian flu–related international conferences, thus preventing Taiwan from effectively sharing its valuable experience in disease prevention. According to Taiwan's National Immigration Agency, an average of 1,200 people travel between Taiwan and China each day, and the number of Taiwanese traveling to the United States averages more than 1,600 per day.

In 2007 Andrew Speaker, an Atlanta man with a strain of tuberculosis that is highly resistant to current drug therapies, flew to France for his honeymoon against the advice of his physicians. While in Italy medical personnel determined that his tuberculosis was the extremely resistant type (XDR-TB). Fearing isolation in an Italian hospital, Speaker flew to Prague, Czech Republic, and Montreal, Quebec, before renting a car, driving to New York City, and checking into a hospital. The CDC tracked people who were in close contact with him, including his fellow aircraft passengers and the flight attendants. Speaker subsequently became the subject of the first federal order for isolation issued in the United States since 1963, raising questions about compulsory quarantines.

While immigration has the potential to spread disease, it also has brought attention to many health issues. Industrialized nations with large immigrant populations, including the United States, have renewed interest in combating neglected diseases (diseases that are rare or eliminated in developed nations) across the globe. For example, international cooperative projects have sought to reduce incidence of tuberculosis and endemic parasitic diseases in Central and South America, as well as encourage screening and treatment for immigrants from those regions.

Internationally Adopted Children—Immigration Status

SOURCE: Miller, Laurie C. “Internationally Adopted Children—Immigration Status.” Pediatrics 103, no. 5 (May 1999): P1078(1).

INTRODUCTION: This letter to the editor of the journal Pediatrics highlights the special vaccination needs of children immigrating to the United States. Laurie C. Miller, a Boston-based physician specializing in internationally adopted children, wrote this letter in 1999 to raise awareness about a concern that remains in 2018. Miller is an associate professor of pediatrics and director ofthe International Adoption Clinic at Tufts University School of Medicine. She is the author of The Handbook Page 475  |  Top of Articleof International Adoption Medicine: A Guide for Physicians, Parents, and Providers (2005).

To the Editor,—

The number of internationally adopted children arriving in the United States has increased dramatically (13,620 in 1997, compared with 9,945 in 1986). Many children have received vaccines in their birth countries; however, the efficacy [effectiveness] of the vaccines and the accuracy of the records are sometimes questionable. Hostetter, et al. have reported protective diphtheria and tetanus titers in only 38 percent of Chinese, Russian, or Eastern European children with written evidence of age-appropriate vaccines.

We have observed that polio titers also may not be protective. Four children in our clinic with written evidence of 3 to 6 polio vaccines were found to have incompletely protective titers. The children were from Lithuania (1), Russia (2), and China (1). They ranged in age from 12 months to 8 years. In 3 children, protective titers to Type 1 and Type 2 polio were found, but no titers to Type 3 polio were measured. In one child, protective titers to Type 1 were absent, but were present for Types 2 and 3.

Although the Red Book recommends that “written documentation should be accepted as evidence of prior immunization,” clinicians caring for internationally adopted children should be aware of the possibility of incomplete immunity to polio, and should either revaccinate or verify immunity to all 3 types of polio. Revaccination or verification of protective titers should be considered for all immunizations in this population.

LAURIE C. MILLER, MD
International Adoption Clinic
New England Medical Center
Boston, MA 02111