West Nile Virus is rising out west, but still has largely disappeared here

The Centers for Disease Control is reporting a puzzling rise in cases of West Nile, the disease caused by the West Nile virus carried by mosquitos, in the Midwest and West. No comparable rise seems to be occurring in New Hampshire, where so far this year the state has found just one set of infected mosquitos, in Manchester, and no infected animals, birds or people. (See results here, in PDF)

West Nile has been a puzzling disease; it stormed through the country after first arriving in New York City in 1999, presumably carried in the gut of a mosquito from oversease, but then it faded away. NH hasn't seen a human case since 2009 or an animal case since 2006. Nobody's sure exactly what happened - perhaps all the easily-infected birds died off (birds were a major carrier, as I'm sure you remember from the days when dead birds were collected and tested).