U.S. – Mexico Cross-Border Health

What's the Problem?

The United States and Mexico share a 1,969-mile border and are deeply connected economically and culturally. Approximately 300 million legal crossings take place from Mexico into the United States annually, and about 15 million Americans visit Mexico each year (1). The sheer number of people who live, work, and travel between the United States and Mexico has led to a sharing of culture and commerce, as well as the easy transportation of infectious diseases. The large movement of people across the United States and Mexico border has led to an increase in health issues, particularly infectious diseases such as tuberculosis.

Who's at Risk?

Besides the millions of travelers who cross the U.S.-Mexico border each year, the border region also has a population of approximately 11 million people, many of whom cross the border daily for a variety of reasons (2). More than 30% of U.S. border families are living at or below poverty level (3), and they are at risk of foodborne, waterborne, and infectious diseases that, for the most part, can be prevented by vaccines.

Can It Be Prevented?

Many different health issues and infectious diseases can cross the U.S.-Mexico border because of the large number of border crossings that occur each year. CDC, along with the Mexican Secretariat of Health, has launched several projects to address these health issues and increase public health coordination between the United States and Mexico. These projects aim to detect, notify, investigate, and respond to illness reports and communicable disease cases; assist cross-border patients with treatment; and coordinate and support bi-national surveillance and disease control projects. CDC’s Division of Global Migration and Quarantine (DGMQ) has staff at U.S. – Mexico border locations who work closely with local, state, federal, and Mexican partners. However, barriers to cross-border disease prevention still remain, as health officials try to utilize limited public health infrastructure, bridge wide communication gaps between the two countries, overcome language and cultural differences, and face major obstacles in the movement of equipment, supplies, specimens, and financial resources across the border.

The Bottom Line

• The U.S.-Mexico border is a unique region where the geopolitical boundary does not inhibit the transmission of infectious diseases among residents on each side of the border.
• The mobility of the U.S.-Mexico border population complicates prevention and investigation of infectious diseases.
• Studies have identified the importance of cross-border movement in the transmission of various diseases, including HIV, measles, pertussis, rubella, rabies, hepatitis A, influenza, tuberculosis, shigellosis, syphilis, Mycobacterium bovis infection, brucellosis, and foodborne diseases, such as infections associated with raw cheese and produce.
• Increased vaccination coverage has produced dramatic declines in the incidence of some infectious diseases, such as measles and hepatitis A.
• The Division of Global Migration and Quarantine works to improve the health of migrating populations through public health partnerships, science, and response at the U.S.-Mexico land border.

Case Example

Bethany and her husband Carlos recently moved to Yuma, Arizona. Shortly after their arrival, Carlos became ill with diarrhea. About two weeks later he started feeling tingling or prickling sensations in his toes and fingers and had trouble breathing. A doctor diagnosed Carlos as having Guillain-Barré Syndrome (GBS). GBS is usually caused by an immune reaction due to a prior infection and can result in paralysis and death. The doctor had been seeing an unusually high number of patients with GBS and called the Arizona Department of Health Services with his observations and concerns. The Arizona Department of Health Services contacted CDC regarding an unusual number of GBS cases in the Yuma area, given that groups of people in one area with GBS are extremely rare. Scientists at DGMQ were intrigued to learn of the GBS cases in Yuma, since they had recently learned of a similar group of GBS cases in the San Luís Río Colorado area of Mexico. Scientists across CDC and DGMQ were involved in the investigation, including foodborne, waterborne illness, and environmental experts. A bi-national meeting was convened in San Luís Río Colorado with state, and local epidemiologists, and the Mexican federal counterparts to plan and initiate a full investigation of the outbreak. These unexpected GBS cases occurred at a rate 26 times higher than usual for the time period in the region. The GBS cases were likely due to campylobacteriosis, an infection with a bacterium polluting various water systems in San Luís Río Colorado, Mexico. CDC conducted an environmental health study to better understand the local water systems and establish relationships with water managers to improve water treatment and disinfection practices.