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Epidemiologic Notes and Reports Transmission of Pertussis from Adult to Infant -- Michigan, 1993

During 1993, a total of 6586 pertussis cases was reported in the United States, including 675 (10%) cases among persons aged greater than 19 years. However, the total number of cases probably was substantially higher because only an estimated 10% of all pertussis cases are reported (1); underreporting is greater among adults, who often have only a mild cough. This report summarizes the investigation of two cases of pertussis in which transmission occurred from an adult resident of Massachusetts who was visiting the residence of an infant in Michigan.

Patient 1. On October 11, 1993, a 4-month-old boy in Ann Arbor, Michigan, developed a mild cough. His symptoms gradually worsened during the following 2 weeks with paroxysms of cough associated with whooping, vomiting, and apnea. A culture of a nasopharyngeal specimen obtained on October 25 yielded Bordetella pertussis. On September 8, the infant had received one dose of diphtheria and tetanus toxoids and pertussis vaccine (DTP). Treatment for the infant and chemoprophylaxis of his household contacts with erythromycin were initiated on October 27 and continued for 2 weeks. Although hospitalization was not required, the infant had a persistent cough for 3 months. The infant had not attended group day care.

Patient 2. During September 17-20, 1993, the infant's 47-year-old aunt from Cambridge, Massachusetts, had visited his home. During the visit, she developed a mild cough. On return to Massachusetts, her cough worsened, and she developed paroxysms of cough with inspiratory whoop and posttussive apnea. On September 23, bronchitis was diagnosed, and she was treated with codeine. On September 29, therapy with a 7-day course of erythromycin and a steroid inhalant was initiated. Because of the history of close contact with her nephew -- in whom a culture-confirmed case of pertussis had been diagnosed -- on November 17, a serum sample was obtained for immunoglobulin G (IgG) antibody to pertussis toxin; the serum IgG concentration was greater than 30 ug/mL * . Inhalant therapy was discontinued, and a 14-day course of erythromycin was prescribed for the patient and three household contacts. Reported by: ED Mokotoff, MPH, Disease Surveillance Section, RA Dunn, MD, Immunization Section, DR Johnson, MD, Disease Control Div, KR Wilcox, Jr, MD, State Epidemiologist, Michigan Dept of Public Health. L Burger, MPH, S Lett, MD, Immunization Program, Massachusetts Dept of Public Health. Div of Epidemiology and Surveillance, National Immunization Program, CDC.

Editorial Note

Editorial Note: The investigation of the two cases described in this report indicates the continuing occurrence of pertussis in adults and that adults can be a source of pertussis infection for susceptible infants. Health-care providers should consider pertussis in the differential diagnoses for acute cough of greater than or equal to 7 days' duration in adults, particularly if the cough is paroxysmal and associated with posttussive vomiting and/or whooping. Although the cough associated with pertussis in adults generally is mild (3), the case in this report indicates that classic symptoms of pertussis (e.g., paroxysms of cough, posttussive whoop, and apnea) can occur in adults.

Laboratory confirmation of pertussis can be difficult because of the low sensitivity of microbiologic cultures and the occurrence of false results from direct fluorescent antibody tests. Serodiagnosis and recently developed polymerase chain reaction tests may be useful for diagnosis, particularly in persons with a mild cough. However, these tests have not been standardized and are not widely available.

Transmission of pertussis can be reduced with prompt diagnosis and treatment of cases and early administration of chemoprophylaxis to close contacts (4). Administration of erythromycin for 14 days is recommended for persons with pertussis and all their household contacts (regardless of age or vaccination status) and is an important method of protecting children aged less than 6 months who are too young to have received the initial three-dose series of DTP recommended during infancy (5,6). Chemoprophylaxis of household contacts with erythromycin should be administered as soon as possible after first contact with a primary case; chemoprophylaxis administered greater than or equal to 21 days after first contact is considered of limited value (7).


  1. Sutter RW, Cochi SL. Pertussis hospitalization and mortality in the United States, 1985-1988. JAMA 1992;267:386-91.

  2. Marchant CD, Loughlin AM, Lett SM, et al. Pertussis in Massachusetts, 1981-1991: incidence, serologic diagnosis, and vaccine effectiveness. J Infect Dis 1994;169:1297-305.

  3. Bass JW. Pertussis: current status of prevention and treatment. Pediatr Infect Dis 1985;4:614-9.

  4. Sprauer MA, Cochi SL, Zell ER, et al. Prevention of secondary transmission of pertussis in households with early use of erythromycin. Am J Dis Child 1992;146:177-81.

  5. ACIP. Diphtheria, tetanus, and pertussis: recommendations for vaccine use and other preventive measures -- recommendations of the Immunization Practices Advisory Committee (ACIP). MMWR 1991;40(no. RR-10).

  6. American Academy of Pediatrics. Pertussis. In: Peter G, ed. 1994 Red book: report of the Committee on Infectious Diseases. 23rd ed. Elk Grove Village, Illinois: American Academy of Pediatrics, 1994:355-67.

  7. Health and Welfare Canada. Pertussis consensus conference. In: Canada communicable disease report. Vol 19-16. Ottawa: Health and Welfare Canada, 1993:124-35.

    • Since 1987, the Massachusetts Public Health Biologic Laboratory has performed an indirect enzyme-linked immunosorbent assay for IgG to pertussis toxin for diagnosis of pertussis among persons aged greater than or equal to 11 years. A serum antipertussis toxin concentration of greater than or equal to 20 ug/mL in one specimen is considered by public health authorities in Massachusetts as evidence of recent infection with B. pertussis (2).

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