Pertussis Clinical Information

Basic information on pertussis for health professionals, including epidemiology, communicability, and treatment of cases and contacts.

Download PDF version formatted for print:
Pertussis Clinical Information (PDF: 38KB/2 pages)

On this page:
Epidemiology of pertussis
Communicability of pertussis
Consider pertussis in these patients
Lab testing encouraged
Antimicrobial therapy
Contacts of pertussis cases
Antimicrobial prophylaxis of close contacts
Immunization of case contacts

Epidemiology of pertussis

  • Bordetella pertussis is endemic in Minnesota.
  • Pertussis occurs year-round, peaking in the later part of the year.
  • Annual incidence peaks every three to five years. 
  • Adolescents and adults represent over half of the reported cases nationally. Even among highly vaccinated populations, waning immunity leads to a substantial number of susceptible older children and adults. Adolescents and young adults can serve as an important reservoir for transmission to young infants, who are at increased risk for serious complications.
  • Although paroxysmal coughing is the most common symptom in reported cases, adolescents, adults, and previously vaccinated persons may exhibit atypical manifestations with persistent cough but no whoop.

Communicability of pertussis

  • Patients are most infectious early in the illness, but communicability may persist for three weeks after onset of cough
  • During the first week of illness, symptoms resemble “the common cold,” and paroxysmal coughing gradually develops during the second week of illness.
  • Antimicrobial therapy decreases communicability and may limit the spread of disease.
  • The bacteria is shed in nasopharyngeal secretions (droplets) and spreads when secretions get into mucous membranes such as the mouth, nose, eyes, or non-intact skin, especially when droplets are disseminated during coughing and sneezing.
  • The incubation period for pertussis is usually seven to 10 days, but can range from four to 21 days.

Advise patients with suspect pertussis to stay home from school, work, or other activities during which they could expose others until they have completed five full days of appropriate antimicrobial treatment.

Exception: If onset of cough was more than three weeks prior, the patient is no longer infectious, even if the cough persists.

Consider pertussis in these patients

MDH encourages providers to consider pertussis in the following patients, regardless of age or vaccination status. Patients exhibiting:

  • Prolonged cough. During outbreaks and periods of increased incidence, pertussis should be considered in the diagnosis of coughs lasting greater than one week.
  • Paroxysmal cough and/or post-tussive vomiting or whoop.
  • Apnea or cyanosis without the characteristic paroxysmal cough, especially in infants.
  • A cough illness of any duration and a known close exposure to a pertussis case. This includes persons notified of potential exposure during an outbreak in a school or other setting.

Lab testing encouraged

Suspect cases of pertussis infection can be confirmed by culture or polymerase chain reaction (PCR). MDH encourages health care providers to perform laboratory testing for those persons with suspect pertussis – particularly those who are household or very close contacts of a laboratory-confirmed case

Whenever possible, both culture and PCR testing should be performed.

  • Culture for B. pertussis is most frequently recovered in the early stages of illness and is rarely found after the fourth week of illness. A negative culture does not necessarily rule out disease. In addition, drug susceptibility testing and molecular epidemiologic study for strain identification require a culture. For that reason, a culture is the preferred test from a public health perspective.
  • PCR testing is highly sensitive and specific and can provide rapid confirmation.
  • The direct fluorescent antibody (DFA) and serology are considered unreliable for laboratory confirmation in Minnesota.

Refer to MDH Pertussis- Laboratory Testing for more information on lab tests that can be done for pertussis, when they should be used, and how to submit specimens to MDH.

Antimicrobial therapy

Give antimicrobial therapy to any patient with a highly suspect or confirmed diagnosis of pertussis. The following three macrolides are equally effective for treatment or prophylaxis of pertussis: azithromycin, clarithromycin, and erythromycin. Trimethoprim-sulfamethoxazole is an alternative.

Patients are considered to be non-infectious after completing the fifth day of appropriate antimicrobial treatment; however, they should complete the full regimen to avoid bacterial relapse.

Some health care providers are reportedly prescribing a one- or three-day course of azithromycin (Zithromax®) in place of the five-day course that is currently one of the standard pertussis treatment options. While this may be appropriate for some respiratory illnesses, the data from published randomized clinical trials using a three-day course for treatment of pertussis are insufficient. The standard recommendations for a five-day course will remain unchanged until new data from comparative studies are available.


See Pertussis - Treatment and Prophylaxis for recommendations on the appropriate dosage and duration of therapy for pertussis.

Contacts of pertussis cases

Local public health will work with the patient and the community to identify close contacts, which may include:

  • Household members (who stay overnight in the same household)
  • Day care contacts in the same home day care or in the same classroom within a day care center (in part because of the increased severity of disease in very young children)
  • Persons who have had direct face-to-face contact with an infectious pertussis case during coughing or sneezing
  • Students participating in extracurricular activities with a pertussis case at least 10 hours per week
  • Other persons spending at least 10 hours per week with an infectious case, during which time they are frequently in close proximity (i.e., within arm’s length)
  • Other contacts identified by public health in an outbreak situation

Antimicrobial prophylaxis of close contacts

Antimicrobial prophylaxis (same regimen as therapy for cases) may be recommended to patients who are asymptomatic but are close contacts of pertussis cases.

  • Antimicrobial prophylaxis is recommended if exposure to an infectious case occurred within the previous 21 days (the maximum incubation period for pertussis).
  • Asymptomatic contacts receiving prophylaxis should not be excluded from their usual activities.
  • Symptomatic contacts should be evaluated as suspect pertussis cases.
  • In general, antimicrobial prophylaxis isn't recommended until there has been laboratory confirmation of the suspect case.

Immunization of case contacts

In addition to providing antimicrobial therapy to case contacts, providers should assess pertussis vaccination status. Use DTaP or Tdap depending on the age of the case contact.

  • Give DTaP to catch-up children under age 7 years for any vaccinations due or overdue.

There are two Tdap vaccines:

  • Adacel, licensed for persons age 11 through 64 years
  • Boostrix, licensed for persons age 10 years and older
  • Give Tdap to children age 7-10 years who have an incomplete DTaP schedule or who have never received a primary series of tetanus, diphtheria, and pertussis. In this instance, initiate a primary series giving Tdap as the first dose, followed by a dose of Td one month later, and a second Td six months later. This off-label use is ACIP recommended.
  • Give Tdap is routinely at age 11-12 years. However, do not wait for the pre-adolescent check-up to provide Tdap to household contacts; give it as early as age 10 years.
  • Give Tdap to adolescents and adults age 13 and older who have not yet received a Tdap. Give the dose regardless of the interval since the last Td.
    • Make special effort to give Tdap to all persons who have or will have contact with children under age 1 year.
  • Give Tdap during every pregnancy, regardless of any doses given before pregnancy, preferably between weeks 27 and 36.

Updated Thursday, November 21, 2013 at 09:04AM