Pertussis

Table of Contents

Disease Information

Pertussis is caused by Bordetella pertussis, a gram-negative bacillus.

Overview

Also known as: Whooping Cough

Responsibilities

  • Hospital: Report by IDSS, facsimile, phone, or mail
  • Lab: Report by IDSS, facsimile, phone, or mail
  • Physician: Report by facsimile, phone, or mail
  • Local Public Health Agency (LPHA): Report by IDSS, Follow-up required

Iowa Department of Public Health
Disease Reporting Hotline: (800) 362-2736
Secure Fax: (515) 281-5698

A. Agent

Pertussis is caused by Bordetella pertussis, a gram-negative bacillus.

B. Clinical Description 

Symptoms: Pertussis symptoms may vary by illness stage as described below:

  • Catarrhal stage: This is the most contagious stage of pertussis. The illness begins insidiously, similar to a common cold, with cough, sneezing, and/or a runny nose, sometimes lasting up to two weeks.
  • Paroxysmal stage: The classic symptoms start with a whooping cough of five to 15 consecutive coughs per single breath, followed by a high-pitched whoop as the person deeply inhales. Moments later another round of coughing occurs, sometimes accompanied by gagging and vomiting. The infected person usually appears normal between attacks. The cough is usually worse at night. Fever is most often absent or minimal throughout the course of the disease. The paroxysmal stage can last one to six weeks.
  • Convalescent stage: This stage can persist for three weeks to three months (seven weeks on average). Even after recovery, classic coughing episodes may recur for months.  This is usually because the person is developing another upper respiratory infection that may irritate the previously damaged airways.

The clinical presentation of pertussis is variable and its diagnosis challenging.

  • Infants under six months old may present with apnea and cyanosis rather than a whooping cough, and usually appear quite ill.
  • Older children and adults also can have atypical manifestations, with persistent cough lasting > two weeks with no whoop, or they may present with more classical symptoms. They may also present with milder symptoms that mimic bronchitis or asthma.

Onset: Pertussis onset is acute or insidious with an irritating cough.

Complications: Complications from pertussis include pneumonia, seizures, encephalopathy, and death.

Duration: With or without treatment, the illness persists for three weeks to three months; the average duration is seven weeks.

B. Reservoir

Humans are the only known reservoir.

D. Modes of Transmission

Spread: Pertussis is most commonly spread by contact with respiratory droplets or by contact with airborne droplets of respiratory secretions. It occurs rarely by contact with an infected person’s freshly contaminated articles.

E. Incubation Period

The incubation period is usually nine to 10 days, with a range of six to 20 days.

F. Period of Communicability or Infectious Period 

Persons with pertussis are most infectious during the catarrhal period and the first two weeks after cough onset (i.e., approximately 21 days).  For the purpose of surveillance and workup:  The person is most efficient at spreading disease once the cough begins. To determine the period of communicability, take cough onset and go out 21 days or until person has completed the first five full days of an appropriate antibiotic.

G. Epidemiology

  • Young infants (particularly preterm infants) are at highest risk for acquiring clinical pertussis and associated complications.  Adolescents and adults are often the source of infection for infants.

  • Pertussis occurs worldwide. It is endemic, with peaks occurring every two to five years.

  • Pertussis exhibits no distinct seasonality in the U.S.; however, it may increase in the summer and fall.
  • Long-term carriage (i.e., several months) of B. pertussis probably does not occur.  However, it has been documented that persons can become infected and remain asymptomatic.  Transmission from asymptomatic infected persons to others may occur but is less likely than for symptomatic persons since asymptomatic persons do not have a cough.
  • Pertussis is highly infectious, with secondary attack rates of 80 to 90 percent among susceptible household contacts.
  • Pertussis vaccine is 70 to 90 percent effective. Immunity wanes five to 10 years after the last dose of pertussis vaccine is given.

H. Bioterrorism Potential

None.

I. Additional Information

The Council of State and Territorial Epidemiologists (CSTE) surveillance case definitions should not affect the investigation or reporting of a case that fulfills the criteria in this chapter. (CSTE case definitions are used by the state health department and the CDC to maintain uniform standards for national reporting.)

Fact Sheets and Forms

References

American Academy of Pediatrics. Red Book 2009: Report of the Committee on Infectious Diseases, 28h Edition. Illinois, American Academy of Pediatrics, 2009.

CDC. Guidelines for the Control of Pertussis Outbreaks. CDC, 2000.

CDC. Pertussis: Summary of Vaccine Recommendations. January, 2011

Heymann, David L., ed., Control of Communicable Diseases Manual, 20th Edition. Washington, DC, American Public Health Association, 2015.

Honein, M.A., Paulozzi, L.J., Himelright, I.M., et al. Infantile hypertrophic pyloric stenosis after pertussis prophylaxis with erythromycin: a case review and cohort study. Lancet 1999; 354:2101–2105.

CDC: Epidemiology and Prevention of Vaccine-Preventable Diseases “Pink Book”. Ninth edition, January 2006.