Health officials have identified a flu strain that sickened about 120 people from at least 25 states who attended a convention in Grand Rapids.
The Kent County Health Department and the Michigan Department of Health and Human Services said Friday that results obtained from Michigan residents confirms three positive cases of Influenza A (H1N1), also known as swine flu.
They say tests conducted by agencies in other states also have also confirmed the H1N1 strain that emerged in 2009 and has been circulating ever since. It has been part of the flu vaccine since 2010.
The Kent County agency says the people who were sickened attended the National Rural Letter Carriers' Association convention at DeVos Place from Aug. 14-17.
Most people who get the flu recover in a few days.