Growing evidence in California suggests that early flu cases had no apparent origin in Mexico. Many of the early California victims — including the first two cases — say they hadn’t traveled to Mexico and had no contact with pigs. Some may have fallen ill before the first Mexicans did…

The first case discovered in California was a 10-year-old boy in San Diego County, who fell ill with a fever March 30…

One possible scenario is that swine flu had been spreading around the U.S.-Mexico border during the winter flu season with few symptoms, then evolved into a more serious form with fever and a cough.