Page last updated 12/20/2023.

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Pertussis, or whooping cough, is an infectious disease caused by the bacterium Bordetella pertussis. Whooping can cause serious illness in people of all ages but is most dangerous for babies. Pertussis is known as “whooping cough” because of the “whooping” sound that people can make when gasping for air after a fit of coughing.

Transmission (Spread)

The bacteria that causes pertussis spreads easily from person-to-person through the air, such as when:

  • A person who has pertussis sneezes or coughs. They can release small particles with the bacteria in them. Other people then breathe in the bacteria.
  • People spend a lot of time together or share breathing space, like when you hold a newborn on your chest.

People can be contagious for weeks. People can spread the bacteria from the start of the very first symptoms and for at least 2 weeks after coughing begins. Taking antibiotics early in the illness may shorten the amount of time someone is contagious.

People can spread the disease even if they don’t know they have it. Some people who have mild symptoms and don’t know they have pertussis can still spread the bacteria to others. Many babies who get pertussis are infected by older siblings, parents, or caregivers who do not know they have it.

The incubation period (the time between infection and the start of symptoms) for pertussis is usually 5 to 10 days after exposure, but can be as long as 21 days.


Pertussis may begin like a common cold, but unlike a cold, the coughing can last for weeks or months. Babies may struggle to breathe, while teens and adults usually have mild symptoms.

Stage 1: Early symptoms can last for 1 to 2 weeks and usually include:

  • Runny or stuffed-up nose;
  • Low-grade fever (less than 100.4°F);
  • Mild, occasional cough (babies do not do this); and
  • Apnea (life-threatening pauses in breathing) and cyanosis (turning blue or purple) in babies and young children.

Stage 2: Later, other symptoms start 1 to 2 weeks after the Stage 1 symptoms start. People may develop rapid, violent, and uncontrolled coughing fits (paroxysms). These coughing fits usually last 1 to 6 weeks, but can last up to 10 weeks. Coughing fits generally get worse and become more common as the illness continues.

Coughing fits can cause people to:

  • Make a high-pitched “whoop” sound when they are finally able to breathe at the end of a coughing fit;
  • Vomit during or after coughing fits; • Feel very tired after the fit, but usually seem well in-between fits; and
  • Struggle to breathe.

Stage 3: Recovery from whooping cough can be slow. The cough becomes milder and less common as you get better. Coughing fits may stop for a while but can return if you get other respiratory infections.



Doctors diagnose pertussis by considering if you have been in contact with someone who has Pertussis and by doing a:

  • History of typical signs and symptoms,
  • Physical exam,
  • Laboratory test of a mucus sample from the back of the throat, and
  • Blood test.


Doctors generally treat pertussis with antibiotics. It’s very important to treat early, before coughing fits begin. Early treatment can make the illness less serious and help prevent spreading the bacteria to others.

See a doctor if you or your child are:

  • Struggling to breathe;
  • Turning blue or purple;
  • Coughing violently;
  • Coughing rapidly, over and over; and
  • Not drinking enough fluids.

If you’ve been exposed to the bacteria that cause pertussis in a friend or family member, talk to your doctor about whether you need preventive antibiotics.

Doctors and local health departments can determine who should get preventive antibiotics. For people exposed to pertussis, the Centers for Disease Control and Prevention (CDC) recommends preventive antibiotics only if they:

  • Live with the person who has been diagnosed with pertussis.
  • Are at increased risk for serious disease (e.g., babies, people with certain medical conditions) or will have close contact with someone who is at increased risk for serious disease (e.g., women in their third trimester of pregnancy, people who work with or care for high-risk individuals).


Pertussis can cause serious and sometimes deadly complications in babies and young children. Teens and adults can also get complications, like pneumonia.

The best way to prevent pertussis is to get vaccinated. Two vaccines in the United States help prevent whooping cough: DTaP and Tdap.

  • These vaccines also provide protection against tetanus and diphtheria.
  • These vaccines cannot give you pertussis, tetanus, or diphtheria.

Practicing good hygiene can also prevent the spread of the bacteria that cause pertussis and other respiratory illnesses.

  • Cover your cough or sneeze.
  • Wash your hands often.


County of San Diego



Resources for Healthcare Professionals


For more information, contact the Epidemiology Unit at 619-692-8499 or send us an e-mail.