I'm not a trained epidemiologist but I do love reading about diseases. This is an extension of my interest in landscapes and how they affect organisms. I follow the infectious disease literature somewhat and I regularly listen to This Week in Parasitism and This Week in Virology. I also subscribe to Promed Mail - a listerv that sends out infectious disease news.
There has been a small outbreak of Chikungunya in the Caribbean Islands that has currently reached 486 known infections. Chikungunya is caused by an arbovirus (short for arthropod borne virus) in the genus Alphavirus. Chikungunya infections are usually not fatal but they can cause long-term joint pain though most infections are cleared in a week. This disease is primarily found in se Asia, central Africa, and some parts of Europe.
Why do I think Chukungunya is coming to the US? The virus is carried by mosquitoes are are ubiquitous throughout the Americas. All the virus needs to get a foothold in the US is for an infected individual (say a tourist) to bring the virus back to the Americas while the virus is circulating in their bloodstream. Then an "American" mosquito can bite the infected person, pick up the virus, and the cycle starts anew. Viola! Around 2004, Chikungunya started spreading out from locations around the Indian Ocean and has spreading globally since then with a large bump in 2007 that appears to related to a change in the virus (Staples et al. 2009).
Staples et al. 2009. http://www.ncbi.nlm.nih.gov/pubmed/19663604