FUO, maybe PHF?

FUO--Fever of Unknown Origin, is a common urgent call for me.  Consider common viral infections like flu or rhinitis, but more sinister is PHF: Potomac Horse Fever.  I've seen a few cases already this summer, and the PHF season (June through October) is just beginning.  http://www.merckvetmanual.com/mvm/digestive_system/intestinal_diseases_in_horses_and_foals/potomac_horse_fever.html