There are two prevailing theories usually postulated.[citation needed] One theory by Alfred W. Crosby is that the virus strain originated at Fort Riley, Kansas, by two genetic mechanisms – genetic drift and antigenic shift – in viruses in poultry and swine which the fort bred for local consumption. Though initial data from a recent reconstruction of the virus suggested that it jumped directly from birds to humans, without traveling through swine,[lower-alpha 1] this has since been cast into doubt. One researcher published in 2004 argued that the disease was found in Haskell County, Kansas, as early as January 1918.[2] A similar and even more deadly virus had been seen earlier at British camps in France and at Aldershot.[3]