In the last 18 months, 34 countries have reported outbreaks.
By July, small outbreaks are being reported around the nation.
Such outbreaks have been reported in a number of cities.
Navajo leaders reported similar outbreaks in 1918, 1933, and 1934.
Some outbreaks among older people living in long-term care facilities also have been reported.
Both smaller outbreaks and sporadic cases have been reported from all the countries above.
Alaska and Montana reported more widespread outbreaks than the other states.
Five companies have voluntarily recalled their spinach products since the outbreak was reported nearly three weeks ago.
The first outbreak was reported after eating amberjack in February 2012.
Further outbreaks of violence were reported in London on 27 March.