By Tom Geoghegan
BBC News, Avenal, California
Cases of an incurable illness called valley fever are multiplying at a mystifying rate in the American south-west. Six states are affected, and Mexico too, but few places have been hit as hard as one remote city.
Even in sweltering heat, the wind brings no respite to Avenal.
The gusts are warm, like a hairdryer, and they carry an invisible threat that has claimed and disrupted many lives.
The tiny city of 14,000 people, nestling in a dip in the floor of the San Joaquin Valley, California, is what experts refer to as a "hot zone" for coccidioidomycosis - an illness caused by the inhalation of tiny fungal spores that usually reside in the soil.
Described by the Centers for Disease Control as a silent epidemic, 22,401 new infections were recorded across the US in 2011, mostly in the south-west, up tenfold from 1998.
Although two-thirds of those infected suffer no symptoms, and the illness is not contagious, about 160 people die each year when the fungus spreads beyond the lungs to the brain.
Avenal is at the centre of the epidemic. While millions flock to the famous Californian beaches a couple of hours to the west and to Yosemite National Park to the east, they rarely linger in the San Joaquin Valley, the state's agricultural heartland. Avenal has the air of a forgotten place.
More story here.