ATLANTA | September 21, 2005
Scientists in Atlanta say they employed a novel use of genetic testing methods to control the spread of food-borne hepatitis A in 2003.
Joseph Amon and colleagues at the Centers for Disease Control and Prevention said the molecular epidemiologic methods had not previously been used in an ongoing investigation of a hepatitis A virus outbreak.
The CDC investigators used genetic sequencing analysis to identify the source of the virus found in blood samples from 422 cases of hepatitis A in Tennessee, North Carolina and Georgia during September 2003.

Preliminary findings suggested three unrelated restaurants were involved. Investigators identified green onions as the likely source by interviewing infected and uninfected restaurant patrons.
In addition to the standard techniques, the researchers also compared viral RNA sequences from case patients and individuals concurrently ill with hepatitis A virus infection in non-outbreak settings in the United States and Mexico.
That helped the CDC scientists to determine the sources of the green onions served in the Tennessee and Georgia restaurants were three farms in northern Mexico.
The study is detailed in the Oct. 15 issue of The Journal of Infectious Diseases, now available online.