Molecular epidemiology of foodborne hepatitis a outbreaks in the United States, 2003.
BACKGROUND
Molecular epidemiologic investigations can link geographically separate foodborne hepatitis A outbreaks but have not been used while field investigations are in progress. In 2003, outbreaks of foodborne hepatitis A were reported in multiple states.


METHODS
Case-control studies were conducted in 3 states. Hepatitis A virus was sequenced from serologic specimens from individuals associated with outbreaks and from individuals concurrently ill with hepatitis A in non-outbreak settings in the United States and Mexico.


RESULTS
Case-control studies in Tennessee (TN), North Carolina (NC), and Georgia (GA) found green onions to be associated with illness among restaurant patrons (TN: odds ratio [OR], 65.5 [95% confidence interval {CI}, 8.9-482.5; NC: OR, 2.4 [95% CI, 0.3-21.9]; GA: OR, 20.9 [95% CI, 3.9-110.3]). Viral sequences from TN case patients differed by 2 nt, compared with those from case patients in NC and GA. A third sequence, differing from the TN and GA/NC sequences by 1 nt, was identified among case patients in a subsequent outbreak in Pennsylvania. Each outbreak sequence was identical to > or =1 sequence isolated from northern Mexican resident(s) with hepatitis A. The sources of green onions served in restaurants in TN and GA were 3 farms in northern Mexico.


CONCLUSIONS
Ongoing viral strain surveillance facilitated the rapid implementation of control measures. Incorporation of molecular epidemiologic methods into routine hepatitis A surveillance would improve the detection of hepatitis A outbreaks and increase our understanding of hepatitis A epidemiology in the United States.
Amon
Joseph J
JJ
Epidemic Intelligence Service, Epidemiology Program Office and Division of Viral Hepatitis, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
Devasia
Rose
R
Xia
Guoliang
G
Nainan
Omana V
OV
Hall
Stephanie
S
Lawson
Brian
B
Wolthuis
Julie S
JS
Macdonald
Pia D M
PD
Shepard
Colin W
CW
Williams
Ian T
IT
Armstrong
Gregory L
GL
Gabel
Julie A
JA
Erwin
Paul
P
Sheeler
Lorinda
L
Kuhnert
Wendi
W
Patel
Priti
P
Vaughan
Gilberto
G
Weltman
Andre
A
Craig
Allen S
AS
Bell
Beth P
BP
Fiore
Anthony
A
D016022:Case-Control Studies; D004196:Disease Outbreaks / Q000706:statistics & numerical data; D005511:Food Handling; D005516:Food Microbiology; D005517:Foodborne Diseases / Q000453:epidemiology / Q000821:virology; D006506:Hepatitis A / Q000453:epidemiology* / Q000209:etiology / Q000401:mortality; D030041:Hepatitis A virus / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D017720:Molecular Epidemiology; D014481:United States / Q000453:epidemiology