At least 66 people have now died in one of the worst West Nile virus outbreaks the US has ever seen. Infections shot up 40% this week, with a total of 1,590 now having fallen ill, USA Today reports. Health officials are warning Americans to do their best to avoid mosquitoes over Labor Day weekend, particularly in Texas, the hardest hit state, where 31 have died. Texas officials are pushing what they call the "Four D's": Use DEET, dress in long sleeves, stay inside at dusk, and drain all standing water. (More Centers for Disease Control and Prevention stories.)