671. Increased Disease Severity and Larger Household Size among Hispanic Infants with Pertussis —Chicago, IL, 2010-2016
Session: Poster Abstract Session: Public Health: Epidemiology and Outbreaks
Thursday, October 4, 2018
Room: S Poster Hall
  • 671_IDWposter.pdf (494.5 kB)
  • Background: Infants experience higher pertussis incidence and mortality compared to other age groups and 85% of infant cases are acquired from a household member. The Chicago Department of Public Health (CDPH) noted increased pertussis incidence among Hispanics from 2014 (5.3 cases per 100,000 population) to 2016 (12.3 cases per 100,000 population) while other ethnicities remained stable.

    Methods: All pertussis cases reported to CDPH through the Illinois National Electronic Disease Surveillance System with onsets from January 1, 2010 to December 31, 2016 were included in the analyses. Variables of interest were age, race/ethnicity, household size, disease severity, healthcare location of diagnosis, and hospitalization. To assess differences in demographic and care-related indicators between Hispanic and Non-Hispanic White (NHW) infants, chi-square tests were performed; risk ratios and 95% confidence intervals were estimated.

    Results: From 2010-2016, 1,036 pertussis cases were reported to CDPH including 276 infants aged <1 year. Among infant cases, 187(68%) were <4 months of age, 143(52%) male, 151(55%) were Hispanic and 54(20%) were NHW. Median household size for infants of all ethnicities was 4 members (range: 0-15). Of all infants with household member size of ≥4 persons (157), 64% were Hispanic. 185 (67%) of infants had ≥1 severe symptom (apnea, cyanosis, pneumonia, seizure, encephalopathy) and 133 (48%) were hospitalized. Diagnosis occurred in the emergency room (ER) for 199 (72%) infants. Hispanics were more likely than NHW to have household member size ≥4 (RR 1.9, p<0.05), severe symptoms (RR 1.6, p<0.05), hospitalization (RR 2.3, p<0.05), and diagnosis in the ER (RR 2.8, p<0.05) [Table 1].

    Conclusion: Among Chicago infant pertussis cases, Hispanic infants have larger household sizes and more severe disease at time of diagnosis compared to NHW.

    Table 1. Chicago Hispanic infant pertussis case characteristics compared to Non-Hispanic Whites (NHW), 2010-2016

    Infant Characteristics


    N (%)

    RR (95% CI)

    Household Size ≥4


    19 (35.2)



    100 (66.2)

    1.9 (1.3-2.8)*

    Severe symptoms


    25 (46.3)



    113 (75.3)

    1.6 (1.2-2.2)*



    14 (25.9)



    90 (59.6)

    2.3 (1.4-3.7)*

    Diagnosis in ER


    16 (29.6)



    124 (82.1)

    2.8 (1.8-4.2)*

    * Significant at p<0.05

    ‡ population=150, 1 patient missing data

    Enrique Ramirez, BA1, Allison Arwady, MD, MPH2, Peter Ruestow, PhD3 and Marielle Fricchione, MD1, (1)Immunization Program, Chicago Department of Public Health, Chicago, IL, (2)Chicago Department of Public Health, Chicago, IL, (3)Communicable Diseases, Chicago Department of Public Health, Chicago, IL


    E. Ramirez, None

    A. Arwady, None

    P. Ruestow, None

    M. Fricchione, None

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