[1] Following a fit of coughing, a high-pitched whoop sound or gasp may occur as the person breathes in.

[13] Protection from pertussis decreases over time, so additional doses of vaccine are often recommended for older children and adults.

[14] Vaccination during pregnancy is highly effective at protecting the infant from pertussis during their vulnerable early months of life, and is recommended in many countries.

[16] In those with the disease, antibiotics are useful if started within three weeks of the initial symptoms, but otherwise have little effect in most people.

[7] In pregnant women and children less than one year old, antibiotics are recommended within six weeks of symptom onset.

[19] The cough from pertussis has been documented to cause subconjunctival hemorrhages, rib fractures, urinary incontinence, hernias, and vertebral artery dissection.

After one or two weeks, the coughing classically develops into uncontrollable fits, sometimes followed by a high-pitched "whoop" sound, as the person tries to inhale.

About 50% of children and adults "whoop" at some point in diagnosed pertussis cases during the paroxysmal stage.

Immunized people can present with a milder infection; they may only have the paroxysmal cough for a couple of weeks and may lack the "whooping" characteristic.

It is an airborne disease (through droplets) that spreads easily through the coughs and sneezes of an infected person.

[24] Outbreaks of whooping cough have been observed among chimpanzees in a zoo and wild gorillas; in both cases, it is considered likely that the infection was acquired as a result of close contact with humans.

Surface proteins of B. pertussis, including filamentous hemagglutinin and pertactin, mediate attachment to the epithelium.

The elevated number of white blood cells leads to pulmonary hypertension, a major cause of death by pertussis.

[30][29] In infants who develop encephalopathy, cerebral hemorrhage and cortical atrophy occur, likely due to hypoxia.

[33] Methods used in laboratory diagnosis include culturing of nasopharyngeal swabs on a nutrient medium (Bordet–Gengou medium), polymerase chain reaction (PCR), direct fluorescent antibody (DFA), and serological methods (e.g. complement fixation test).

[34] The bacteria can be recovered from the person only during the first three weeks of illness, rendering culturing and DFA useless after this period.

[38] Preventive antibiotics, however, are still frequently used in those who have been exposed and are at high risk of severe disease (such as infants).

[42] The 21st-century resurgence in pertussis infections is attributed to a combination of waning immunity and bacterial mutations that elude vaccines.

[19][44] An effect of widespread immunization on society has been the shift of reported infections from children aged 1–9 years to infants, adolescents, and adults, with adolescents and adults acting as reservoirs for B. pertussis and infecting infants who have had fewer than three doses of vaccine.

[38] Newer macrolides are frequently recommended due to lower rates of side effects.

[6] Trimethoprim-sulfamethoxazole (TMP/SMX) may be used in those with allergies to first-line agents or in infants who have a risk of pyloric stenosis from macrolides.

[21] While most healthy older children and adults fully recover, infection in newborns is particularly severe.

According to the 2024[update] CDC, reports that cases of whooping cough have reached their highest levels since 2014.

[citation needed] The United States is seeing a return to pre-pandemic trends, where annual cases typically exceed 10,000.[66]B.

In 1925 Danish physician Thorvald Madsen was the first to test a whole-cell vaccine on a wide scale.

[67][68][69] In 1932, an outbreak of whooping cough hit Atlanta, Georgia, prompting pediatrician Leila Denmark to begin her study of the disease.

Over the next six years, her work was published in the Journal of the American Medical Association, and in partnership with Emory University and Eli Lilly & Company, she developed the first safe and effective pertussis vaccine.

[71] To minimize the frequent side effects caused by the pertussis component, Japanese scientist Yuji Sato developed an acellular vaccine consisting of purified haemagglutinins (HAs: filamentous strep throat and leukocytosis-promoting-factor HA), which are secreted by B. pertussis.