Though the CDC doesn’t have an official response to that question, the director of the CDC’s Vector-Borne Infectious Disease Division said that ‘unusually warm weather’may be to blame. So far, 2012 is the hottest year on record in the United States according to the National Climatic Data Center, with record-breaking temperatures and drought a national norm. It’s likely no coincidence that some of the states hit hardest by West Nile are also feeling the brunt of the heat. More than half of cases have been reported from Texas alone, where the scorching heat has left only 12% of the state drought-free. Fifteen heat records were broken in Texas just last week on August 13th.

The heat waves, droughts and other weather events are the direct effects of climate change say leading scientists. As NASA researcher James Hansen explained in a recent Washington Post editorial, “our analysis shows that, for the extreme hot weather of the recent past, there is virtually no explanation other than climate change.” He says that the European heat wave of 2003, the Russian heat wave of 2010 and catastrophic droughts in Texas and Oklahoma last year are all the repercussions of climate change. Confidently, he adds that “once the data are gathered in a few weeks’ time, it’s likely that the same will be true for the extremely hot summer the United States is suffering through right now.”

The fact that the worst US West Nile epidemic in history happens to be occurring during what will likely prove to be the hottest summer on record doesn’t surprise epidemiologists. They have been predicting the effects of climate change on West Nile for over a decade. If they’re right, the US is only headed for worse epidemics.