title: Estimating the attack rate of pregnancy-associated listeriosis during a large outbreak.
abstract: BACKGROUND
  In 2011, a multistate outbreak of listeriosis linked to contaminated cantaloupes raised concerns that many pregnant women might have been exposed to Listeria monocytogenes. Listeriosis during pregnancy can cause fetal death, premature delivery, and neonatal sepsis and meningitis. Little information is available to guide healthcare providers who care for asymptomatic pregnant women with suspected L. monocytogenes exposure.
  
  
  METHODS
  We tracked pregnancy-associated listeriosis cases using reportable diseases surveillance and enhanced surveillance for fetal death using vital records and inpatient fetal deaths data in Colorado. We surveyed 1,060 pregnant women about symptoms and exposures. We developed three methods to estimate how many pregnant women in Colorado ate the implicated cantaloupes, and we calculated attack rates.
  
  
  RESULTS
  One laboratory-confirmed case of listeriosis was associated with pregnancy. The fetal death rate did not increase significantly compared to preoutbreak periods. Approximately 6,500-12,000 pregnant women in Colorado might have eaten the contaminated cantaloupes, an attack rate of ~1 per 10,000 exposed pregnant women.
  
  
  CONCLUSIONS
  Despite many exposures, the risk of pregnancy-associated listeriosis was low. Our methods for estimating attack rates may help during future outbreaks and product recalls. Our findings offer relevant considerations for management of asymptomatic pregnant women with possible L. monocytogenes exposure.
authors.affiliation: Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA ; Epidemic Intelligence Service, Scientific Education and Professional Development Program Office, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA.
authors.forename: Maho
authors.initials: M
authors.lastname: Imanishi
authors.affiliation: Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA ; Epidemic Intelligence Service, Scientific Education and Professional Development Program Office, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA.
authors.forename: Janell A
authors.initials: JA
authors.lastname: Routh
authors.affiliation: El Paso County Public Health, Colorado Springs, CO 80907, USA.
authors.forename: Marigny
authors.initials: M
authors.lastname: Klaber
authors.affiliation: Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
authors.forename: Weidong
authors.initials: W
authors.lastname: Gu
authors.affiliation: Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
authors.forename: Michelle S
authors.initials: MS
authors.lastname: Vanselow
authors.affiliation: Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
authors.forename: Kelly A
authors.initials: KA
authors.lastname: Jackson
authors.affiliation: Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
authors.forename: Loretta
authors.initials: L
authors.lastname: Sullivan-Chang
authors.affiliation: Denver Health and Hospital Authority, Denver, CO 80204, USA.
authors.forename: Gretchen
authors.initials: G
authors.lastname: Heinrichs
authors.affiliation: Epidemic Intelligence Service, Scientific Education and Professional Development Program Office, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA ; Tri-County Health Department, Greenwood Village, CO 80111, USA.
authors.forename: Neena
authors.initials: N
authors.lastname: Jain
authors.affiliation: El Paso County Public Health, Colorado Springs, CO 80907, USA.
authors.forename: Bernadette
authors.initials: B
authors.lastname: Albanese
authors.affiliation: Division of Reproductive Health, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA.
authors.forename: William M
authors.initials: WM
authors.lastname: Callaghan
authors.affiliation: Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Mahon
authors.affiliation: Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Silk
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003120:Colorado / Q000453:epidemiology; D028463:Cucumis melo / Q000382:microbiology*; D004196:Disease Outbreaks; D005260:Female; D005313:Fetal Death; D005516:Food Microbiology; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D008089:Listeria monocytogenes; D008088:Listeriosis / Q000453:epidemiology*; D011159:Population Surveillance; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology*