- Clinical science
Pertussis, or whooping cough, is a highly infectious disease of the respiratory tract caused by the gram-negative bacteria Bordetella pertussis. The disease is mainly transmitted via airborne droplets and is most commonly occurs in children. Typically, pertussis manifests in three stages, with the second and third stage characterized by intense paroxysmal coughing that is followed by a distinctive whooping sound on inhalation and, in some cases, vomiting. Young infants may not develop the typical cough, and often present with apnea and cyanosis instead. The disease is most often diagnosed via laboratory tests, especially detection of B. pertussis in bacterial culture. However, as test results may take time to obtain, treatment should be initiated as soon as clinical suspicion of pertussis arises. Subsequent management includes hospitalization of high-risk patients (e.g., infants) and antibiotic therapy with macrolides. These may lessen the length and severity of the disease if administered early, while also reducing infectivity and further disease transmission. Macrolides are also the drug of choice for post-exposure prophylaxis (PEP), which is recommended for all people with a recent history of exposure to pertussis. PEP is administered regardless of the individual immunization status, as both vaccination and prior infection may shorten the disease course, but do not provide full immunity.
- Typically a childhood disease (particularly children aged < 1 year); however, older patients are increasingly affected. 
- High rate of infections in newborns: Tdap vaccine is recommended for pregnant women between weeks 27 and 36 of gestation. 
Epidemiological data refers to the US, unless otherwise specified.
- Pathogen: Bordetella pertussis is a gram‑negative, obligate aerobic coccobacillus.
- Transmission: airborne droplet (through coughing); direct contact with oral or nasal secretions
- Incubation period: on average 7–10 days (range 4–21 days)
- Proliferation of Bordetella pertussis on ciliated epithelial cells of the respiratory mucosa → production of virulence factors (e.g., tracheal cytotoxin) → paralysis of respiratory epithelium cilia and inflammation → secretion of inflammatory exudate into respiratory tract → compromise of small airways → cough, pneumonia, cyanosis 
- Bordetella pertussis produces pertussis toxin → ADP-ribosylation of the α subunit of Gi protein → inhibition of Gi protein → adenylate cyclase disinhibition → cAMP accumulation → impaired cell signaling pathways 
- Pertussis toxin is responsible for most of the systemic manifestations associated with whooping cough (e.g. hypoglycemia, lymphocytosis, modulation of host immune response).
- Neither vaccination nor actual infection confers complete or lifelong immunity.
Catarrhal stage (1–2 weeks)
- Nonspecific symptoms similar to an upper respiratory infection (mild cough, watery nasal discharge, rarely low-grade fever)
- Possibly conjunctivitis
Paroxysmal stage (2–6 weeks)
Intense paroxysmal coughing (often occurring at night)
- Followed by a deep and loud inhalation or high-pitched whooping sound
- Accompanied by tongue protrusion , gagging, and struggling for breath
- Possibly accompanied by cyanosis
- Increases in frequency and severity throughout the stage
- Followed by the expulsion of phlegm or posttussive vomiting (risk of dehydration)
- Potential bleeding of the conjunctiva, petechiae, and venous congestion
- Infants (< 6 months) may only develop apnea and not the characteristic cough.
Convalescent stage (weeks to months)
- Progressive reduction of symptoms
- Coughing attacks may persist over several weeks before resolving
Catarrhal stage manifests with Coryza, while the Paroxysmal stage manifests with Posttussive vomiting and whooPing cough.
A presumptive diagnosis of pertussis may be made based on clinical history and findings. However, if possible, laboratory tests should be performed to confirm the diagnosis.
- Clinical diagnosis possible in patients with a cough lasting ≥ 2 weeks and at least one of the following symptoms:
- Inquire about immunization history and possible contact with infectious persons.
Laboratory tests 
- Blood count: lymphocyte-predominant leukocytosis (50,000–60,000/μL) that corresponds with disease severity
- Pathogen detection (to confirm the diagnosis)
As B. pertussis only grows on respiratory epithelium, blood cultures are always negative.
General approach 
- Early initiation of treatment, especially in high-risk patients (e.g., infants), while confirmatory laboratory tests are pending
- Hospitalization and monitoring: infants < 4 months; severe cases (e.g., respiratory distress, cyanosis, apnea, inability to feed)
- Oxygen administration with humidification
- Increased fluid intake and nutritional support
- If necessary, sedation
Medical therapy 
- Macrolides (e.g., azithromycin, clarithromycin, erythromycin)
- Early administration may lessen symptoms of the catarrhal stage and early paroxysmal stage.
- Late antibiotic administration has little influence on disease severity but reduces infectivity.
- In children > 3 months: very good; lengthy convalescence, but full recovery
- In children < 3 months: mortality 1–3%, particularly due to apnea
- Increased risk for complications
- Premature infants
- Children < 6 months
- People with underlying cardiac, pulmonary, neurologic, or neuromuscular disease
- Routine immunization: DTaP vaccine (diphtheria, tetanus, and pertussis) at 2, 4, 6, and 15–18 months and at 4–6 years (see “ ”)
Booster vaccination: Tdap vaccine
- Single dose at 7–10 years of age if immunization is incomplete
- Single-dose boost at 11–18 years of age, at least 10 years following the last dose
- Contraindications: known anaphylactic reactions, encephalopathy following previous vaccination 
Post-exposure prophylaxis 
- Choice of antibiotics identical to treatment recommendations (see “Therapy” above)
- Administered to household and close contacts of infected people (especially people at risk of developing complications or close contacts of high-risk individuals; see “Complications” above)
- Administered regardless of immunization status
Pertussis is a notifiable disease.