478. Sparing of Pregnant Women During a Large Listeriosis Outbreak — Colorado, August–October 2011
Session: Poster Abstract Session: Public Health
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
  • IDWeek_COPregList_0920.pdf (882.7 kB)
  • Background:

    In pregnant women, Listeria monocytogenes infection (listeriosis) is a non-specific febrile illness that can result in fetal loss and neonatal illness and death. About 16% of cases in the United States are pregnancy-associated. Limited data are available on attack rates among persons who eat products contaminated with Listeria. During a large multistate outbreak in 2011 (147 cases), we estimated the attack rate of listeriosis among pregnant women in Colorado who ate contaminated cantaloupe from implicated Farm A. 


    Using Colorado routine reportable disease surveillance data, we identified outbreak-associated cases in pregnant women. We conducted enhanced surveillance for fetal death using data from 9 hospitals, vital records, and chart reviews of 28 fetal deaths. We surveyed 1,060 pregnant women on symptoms and exposures and estimated the number of pregnant women exposed to Farm A cantaloupe in Colorado using three methods involving U.S. Census data, survey results, and retail and industry data. We calculated the attack rate by dividing the number of pregnancy-associated outbreak cases in Colorado by the estimated number of pregnant Colorado residents who likely ate Farm A cantaloupe during the outbreak.

    Results: One (2.5%) of 40 outbreak-associated cases in Colorado was pregnancy-associated. No significant increase in fetal death rates was detected during the outbreak period. Available clinical, pathology, and laboratory data did not suggest Listeriaas the etiology of any fetal deaths. Twenty-two (2.5%) of 883 pregnant women surveyed reported fever, which was not significantly more common among women who ate cantaloupe. We estimated that 5,700–7,900 pregnant women were exposed to contaminated cantaloupe, with estimated attack rates ranging from 1.3–1.8 cases per 10,000 exposed pregnant women.


    Although a large number of pregnant women were likely exposed to contaminated cantaloupe during the 2011 outbreak, the attack rate of pregnancy-associated listeriosis was low. Our findings, which support experts’ opinions that testing and prophylactic treatment of exposed asymptomatic or mildly-symptomatci pregnant women are not indicated, may be useful during future Listeria outbreaks and product recalls when patient exposures are suspected.

    Maho Imanishi, VMD, MPH1, Janell Routh, MD, MHS2, Marigny Klaber, MSc3, Michelle Vanselow, MD2, Weidong Gu, MD, PhD2, Kelly Jackson, MPH2, Loretta Sullivan-Chang, MD, MPH2, Neena Jaine, MD MSTPH2, Gretchen Heinrichs, MD4, Bernadette Albanese, MD, MPH5, Barbara E. Mahon, MD, MPH2 and Benjamin Silk, PhD, MPH2, (1)Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA, (2)Centers for Disease Control and Prevention, Atlanta, GA, (3)El Paso County Public Health, Colorado Springs, CO, (4)Denver Health, Denver, CO, (5)Boulder County Public Health, Boulder, CO


    M. Imanishi, None

    J. Routh, None

    M. Klaber, None

    M. Vanselow, None

    W. Gu, None

    K. Jackson, None

    L. Sullivan-Chang, None

    N. Jaine, None

    G. Heinrichs, None

    B. Albanese, None

    B. E. Mahon, None

    B. Silk, None

    See more of: Public Health
    See more of: Poster Abstract Session

    Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 2nd with the exception of research findings presented at the IDWeek press conferences.