The disease is spread by triatomines, also called kissing bugs for their tendency to bite on the lips to suck blood. They are often found in cracks and holes in walls and foundations in decrepit homes. Susan Montgomery of the parasitic diseases branch of CDC said this disease is not new to the United States. "It's been here for a long, long time," she said. "The vector bugs have been here probably for centuries."
She also said this illness is not spreading here the way it does in Latin America because the vectors are different, though their ranges are influenced by climate. "There is no evidence that [Chagas] is an increased problem at this point. We don't live in the kind of housing that would put us in contact with triatomine bugs," Montgomery said. "Our triatomine bugs live in the brush, they live in the woods. They are not adapted to live in people's homes."
Arriving with illegal immigrants
Changes in Chagas' prevalence are therefore related to infected people migrating to the United States. "The concentration of positive blood donors is in areas with larger concentrations of immigrant populations," Montgomery said. Cases emerge occasionally in Texas and Oklahoma, but triatomines do not seem to be spreading any farther.
However, as the economy improves, immigration may become a greater disease pipeline. "A lot of people don't come here through the so-called legal channels," said Marian McDonald, associate director for health disparities at the National Center for Emerging and Zoonotic Infectious Diseases (NCEZID) at CDC. "Changes in the global economy have really sort of propelled immigration to the United States, and that doesn't seem like it would change anytime soon."
Since undocumented immigrants are difficult to track, officials have a hard time measuring and treating infected individuals, especially for diseases like Chagas that can remain dormant for years. "Overall, the problem for the population that is vulnerable is that they may not have any idea that they are at risk or that they may have been exposed to it," McDonald said. Legal immigrants from endemic regions are treated for these diseases when they enter the United States.
Poverty is another compounding factor. Undocumented immigrants tend to live in areas with poor quality housing, intermittent garbage pickup and impure water, creating havens for infections. These illnesses can also hamper economic development. "They actually are a cause of poverty because they interfere with child growth and development and pregnancy outcomes," said Hotez, noting that these complications can follow someone for life.
Another disease, Chikungunya, may also set up shop in the United States. The disease's name means "that which bends up" in the Makonde language in East Africa, since the afflicted are often contorted from joint pains. The disease spreads through mosquitoes, particularly the Asian tiger mosquito, an invasive species that is expanding from the southeastern United States and may reach as far north as New York.
Laura Harrington, an associate professor of entomology at Cornell University, expects this disease to become a bigger issue in the future. "It's not a matter of if, it's a matter of when," she said. The disease, which has no cure or vaccine, has been seen in travelers returning to the United States from endemic regions in 2006 and may find a new home here, since many infected don't show any signs. "The danger of Chikungunya virus being introduced into the Americas is increasingly real," said a 2011 CDC report.
Help isn't on the way -- yet
Volatile weather and warming temperatures also influence neglected tropical diseases and their vectors. "Anything that impacts climate is likely to have a significant impact on disease incidence," said C. Ben Beard, associate director for climate change at NCEZID.