Bordetella is a genus of bacteria best known for causing two familiar respiratory infections: whooping cough in humans and kennel cough in dogs. Several species exist within the genus, each targeting different hosts, but they all share a preference for the respiratory tract and a similar method of attack: attaching to the hairlike structures (cilia) lining the airways, paralyzing them, and triggering inflammation that traps mucus in the lungs.
If you’ve encountered the term at a veterinarian’s office, you’re probably hearing about the dog-specific species. If you’ve encountered it in the context of childhood vaccines, you’re hearing about the human version. Here’s what each looks like and why it matters.
The Main Bordetella Species
Three species cause the vast majority of illness. Bordetella pertussis and Bordetella parapertussis infect humans, with B. pertussis responsible for classic whooping cough and B. parapertussis causing a milder form. Bordetella bronchiseptica lives in the respiratory tracts of dogs, cats, and rabbits, and only rarely crosses over to humans. Two additional species, B. avium and B. hinzii, cause respiratory disease in poultry and are almost never found in people.
How Bordetella Infects the Airways
Regardless of species, these bacteria follow a similar playbook. They spread through airborne droplets, land on the lining of the trachea and bronchial tubes, and latch onto the cilia that normally sweep mucus and debris out of the lungs. Once attached, the bacteria release toxins that paralyze those cilia and inflame the surrounding tissue. With the body’s clearance system disabled, mucus builds up in the airways, causing the persistent, sometimes violent coughing that defines both whooping cough and kennel cough.
Whooping Cough in Humans
Whooping cough caused by B. pertussis moves through three distinct stages. The first stage looks like a mild cold: runny nose, low fever, and an occasional cough that gradually worsens over one to two weeks. This is the stage where antibiotics can still shorten the illness and reduce how contagious you are. Once started later, antibiotics won’t change the course of the disease.
The second stage is what gives the illness its name. Coughing fits become intense and rapid, sometimes followed by a high-pitched “whoop” as the person gasps for air. These paroxysms average about 15 episodes per day, are worse at night, and can cause vomiting, exhaustion, and even brief periods where the skin turns blue from lack of oxygen. This phase typically lasts two to three weeks at peak intensity before slowly tapering off.
The third stage is a gradual recovery. The coughing fits become less frequent and less severe, usually fading over two to three weeks. Even after recovery, though, coughing episodes can flare up again with subsequent colds or respiratory infections for months.
Infants are at the highest risk for serious complications, including pneumonia and breathing pauses (apnea). Adults generally tolerate the infection better but can still experience weeks of debilitating coughing.
Recent Trends in Pertussis Cases
Pertussis cases dropped sharply during the COVID-19 pandemic, likely because of masking and social distancing. That changed dramatically in 2024, when reported cases in the United States surged to more than six times the 2023 numbers, exceeding even pre-pandemic levels from 2019. Cases have been trending down since a peak in November 2024, but 2025 numbers remain elevated compared to the years immediately before the pandemic.
One key factor behind the resurgence is waning immunity. Protection from acellular pertussis vaccines fades over time, meaning even vaccinated people can become infected. The CDC expects pertussis to continue occurring in both vaccinated and unvaccinated populations as typical infection patterns return.
Vaccination for Humans
The pertussis vaccine is bundled with diphtheria and tetanus protection. Children receive a five-dose series called DTaP, starting at 2 months of age with additional doses at 4 months, 6 months, 15 to 18 months, and 4 to 6 years. Adolescents and adults get a booster called Tdap, which contains a lower dose of the pertussis component. Pregnant women are also recommended to receive Tdap during each pregnancy to pass protective antibodies to the newborn before birth.
Diagnosing Pertussis
The standard test is a PCR swab of the back of the nose, which detects bacterial DNA. PCR works best during the first three weeks of coughing. After the fourth week, bacterial DNA drops off quickly, increasing the chance of a false negative. If you’ve already been on antibiotics for five or more days, testing is generally not useful either, since the medication clears enough bacteria to make results unreliable.
Kennel Cough in Dogs
Bordetella bronchiseptica is one of the most common causes of kennel cough, formally known as infectious tracheobronchitis. The name comes from how easily it spreads in places where dogs congregate: boarding facilities, dog parks, grooming salons, and shelters. The incubation period is roughly six days, though it can range from two to ten.
The hallmark symptom is a loud, persistent “honking” cough that sounds like the dog is trying to clear something from its throat. After a coughing episode, dogs often cough up mucus. Activity tends to make the coughing worse. Other signs include sneezing, nasal or eye discharge, mild fever, lethargy, and decreased appetite. Most healthy adult dogs recover on their own within a couple of weeks, but puppies are more vulnerable to developing pneumonia, which can involve labored breathing and requires veterinary attention.
Bordetella Vaccine for Dogs
A Bordetella vaccine is available in three forms: oral, intranasal, and injectable. The oral and intranasal versions use live but weakened bacteria and require only a single dose for puppies or previously unvaccinated dogs. The injectable version is an inactivated form and typically requires two initial doses. Annual boosters are considered sufficient for ongoing protection.
Most boarding facilities, doggy daycares, and groomers require proof of Bordetella vaccination. If your dog will be in any group setting within six months, vaccination beforehand is the standard recommendation. The mucosal vaccines (oral or intranasal) tend to provide faster local immunity in the airways compared to the injectable form, which is why many veterinarians prefer them for dogs heading into high-exposure situations.