Listeria monocytogenes infection from foods prepared in a commercial establishment: a case-control study of potential sources of sporadic illness in the United States.
BACKGROUND
Listeria monocytogenes has been estimated to cause >2500 illnesses and 500 deaths annually in the United States. Efforts to reduce foodborne listeriosis have focused on foods frequently implicated in outbreaks. Potential sources for L. monocytogenes infection not associated with outbreaks remain poorly understood.


METHODS
The Foodborne Diseases Active Surveillance Network conducts surveillance for culture-confirmed listeriosis at clinical laboratories in 9 states. After excluding outbreak-associated cases, we attempted to enroll eligible case patients with L. monocytogenes infection in a case-control study from 2000 through 2003. Control subjects were recruited through health care providers and were matched to case patients by state, age, and immunosuppression status. Data were collected about exposures occurring in the 4 weeks before specimen collection from the case patients.


RESULTS
Of the 249 case patients with L. monocytogenes infection, only 12 (5%) had cases that were associated with outbreaks; 6 other patients were ineligible for other reasons. Of 231 eligible case patients, 169 (73%) were enrolled in the study. We classified 28 case patients as having pregnancy-associated cases. We enrolled 376 control subjects. In multivariable analysis, L. monocytogenes infection was associated with eating melons at a commercial establishment (odds ratio, 2.6; 95% confidence interval, 1.4-5.0) and eating hummus prepared in a commercial establishment (odds ratio, 5.7; 95% confidence interval, 1.7-19.1).


CONCLUSIONS
Most cases of L. monocytogenes infection were not associated with outbreaks. Reducing the burden of foodborne listeriosis may require interventions directed at retail environments and at foods, such as melons and hummus, that are not commonly recognized as high risk. Because of the severity of listeriosis, pregnant women and other persons at risk may wish to avoid eating these newly implicated foods.
Varma
Jay K
JK
Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
Samuel
Michael C
MC
Marcus
Ruthanne
R
Hoekstra
Robert M
RM
Medus
Carlota
C
Segler
Suzanne
S
Anderson
Bridget J
BJ
Jones
Timothy F
TF
Shiferaw
Beletshachew
B
Haubert
Nicole
N
Megginson
Melanie
M
McCarthy
Patrick V
PV
Graves
Lewis
L
Gilder
Thomas Van
TV
Angulo
Frederick J
FJ
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D005502:Food; D005506:Food Contamination / Q000706:statistics & numerical data*; D005511:Food Handling; D005519:Food Preservation; D005517:Foodborne Diseases / Q000453:epidemiology / Q000382:microbiology; D006801:Humans; D015994:Incidence; D007223:Infant; D008089:Listeria monocytogenes / Q000302:isolation & purification*; D008088:Listeriosis / Q000175:diagnosis / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011159:Population Surveillance; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology* / Q000382:microbiology; D012016:Reference Values; D012307:Risk Factors; D017678:Sex Distribution; D015996:Survival Rate; D014481:United States / Q000453:epidemiology