Pertussis (whooping cough)

Last updated: December 2024

 

Pertussis is a highly contagious infection of the respiratory tract caused by the bacterium Bordetella pertussis.
It is transmitted via airborne droplets spread by infected people (by coughing and/or sneezing), particularly within 3 weeks of the onset of cough [1] Citation 1. Pertussis vaccines: WHO position paper – August 2015. Wkly Epidemiol Rec. 2015;(35):433-458. https://iris.who.int/bitstream/handle/10665/242413/WER9035_433-458.PDF [Accessed May 17, 2024]. . Despite the development of effective vaccines, it remains an important cause of morbidity and mortality, particularly in infants.

 

This disease is endemic worldwide and outbreaks are common.  It most commonly affects children < 5 years, but can affect any age group. Reported incidence in adolescents and adults has been increasing in some regions [2] Citation 2. Güris D, Strebel PM, Bardenheier B, et al. Changing Epidemiology of Pertussis in the United States: Increasing Reported Incidence Among Adolescents and Adults, 1990‐1996. Clin Infect Dis. 1999;28(6):1230-1237.
https://doi.org/10.1086/514776 [Accessed September 10, 2024]. .

 

Pertussis is a notifiable disease in many countries, and cases should be reported to local or national public health authorities. Pertussis immunization is part of all vaccination schedules and is included in the Expanded Programme on Immunization (EPI).

Clinical features

After an incubation period of 7 to 10 days (up to 21 days), the illness evolves in 3 stages [3] Citation 3. Daniels HL, Sabella C. Bordetella pertussis (Pertussis). Pediatr Rev. 2018;39(5):247-257.
https://doi.org/10.1542/pir.2017-0229 [Accessed September 11, 2024]. :

 

• Catarrhal stage (1 to 2 weeks, but may be shorter in infants < 6 months):
  • Runny nose, mild cough, no or low-grade fever.
  • During this stage, the disease is indistinguishable from other non-specific respiratory infections.

 

• Paroxysmal stage (1 to 6 weeks):
  • Cough of increasing severity, occuring in characteristic bouts (paroxysms) of a series of coughs during one exhalation, followed by a laboured inspiration causing a distinctive gasping sound (whoop), and/or post-tussive vomiting. 
  • No or low-grade fever. 
  • Apnoea and cyanosis (in infants).
  • Prolonged cough, sometimes without paroxysms or whoop (particularly in older children and adults).

 

Complications may include secondary bacterial pneumonia (new-onset fever can be an indicator), dehydration and malnutrition triggered by feeding difficulty due to cough and vomiting, seizures, encephalopathy, sudden death, intracranial bleeding, petechiae, rib fracture, hernia, rectal prolapse.

 

• Convalescent stage (weeks to months):
  • Paroxysms of cough gradually decrease in frequency and severity.

 

The disease is most severe, with a high risk of death, in infants. Adolescents and adults commonly have milder symptoms, but older adults, immunocompromised persons, and people with underlying respiratory conditions are at risk of severe disease and hospitalisation [4] Citation 4. Mbayei SA, Faulkner A, Miner C, et al. Severe Pertussis Infections in the United States, 2011–2015. Clin Infect Dis. 2019;69(2):218-226.
https://doi.org/10.1093/cid/ciy889 [Accessed September 13, 2024] .

 

Pertussis is most contagious and antibiotic treatment is most beneficial during the catarrhal stage of the illness. Since this is also the period during which clinical symptoms and signs are non-specific, it is necessary to maintain a high index of suspicion with clues from the context. These include patients with any compatible symptoms and close contact with a suspected case or in a pertussis outbreak setting.

Antibiotic treatment

Antibiotic treatment is indicated for the following patients [5] Citation 5. Centers for Disease Control and Prevention. For Clinicians: Pertussis Treatment. Published online August 4, 2022.
https://www.cdc.gov/pertussis/clinical/treatment.html [Accessed April 28, 2024]. and should be started as soon as pertussis is suspected:

• All patients 1 year of age and older, within 3 weeks of the onset of cough.
• Infants and pregnant women, within 6 weeks of the onset of cough.

 

First line
azithromycin PO for 5 days	Children < 6 months: 10 mg/kg once daily Children ≥ 6 months: 10 mg/kg (max. 500 mg) on D1 then 5 mg/kg (max. 250 mg) once daily from D2 to D5 Adults: 500 mg on D1 then 250 mg once daily from D2 to D5
Alternatives
erythromycin PO (a) Citation a. Erythromycin is an alternative, but azithromycin is better tolerated and simpler to administer (shorter treatment duration, fewer daily doses). for 7 days	Children: 15 mg/kg 3 times daily Adults: 1 g 3 times daily
co-trimoxazole PO (b) Citation b. Use co-trimoxazole only if macrolides are contra-indicated, not tolerated, or not available. Avoid: - during the first trimester of pregnancy (risk of congenital malformations), - after 36 weeks of pregnancy and in women breastfeeding neonates (0 to 4 weeks), or breastfeeding infants that are premature, low birth weight, jaundiced, or ill (risk of haemolysis and jaundice in the child). Advise patients to seek immediate medical attention if there are signs of anaemia or jaundice, especially in regions with high prevalence of G6PD deficiency. for 14 days	Children ≥ 6 weeks: 20 mg SMX/4 mg TMP/kg (max. 800 mg SMX/160 mg TMP) 2 times daily Adults: 800 mg SMX/160 mg TMP 2 times daily

 

Admit the following patients to hospital

• Patients with severe illness (e.g. respiratory distress, apnoea, cyanosis, pneumonia, seizures or impaired consciousness)
• Infants up to 3 months of age (with monitoring 24 hours per day due to the risk of apnoea)
• Patients with difficulty in feeding or drinking

 

Infection prevention and control measures

Patients with pertussis are considered infectious until they have completed 5 days of appropriate antibiotics, or if not treated, until 21 days after the start of the paroxysmal cough [1] Citation 1. Pertussis vaccines: WHO position paper – August 2015. Wkly Epidemiol Rec. 2015;(35):433-458. https://iris.who.int/bitstream/handle/10665/242413/WER9035_433-458.PDF [Accessed May 17, 2024]. . During this infectious period, these measures should be followed:

• In hospital: single room if possible, or grouping pertussis cases together away from other patients (cohorting); standard precautions and droplet precautions (including, for the patient, cough etiquette and wearing a surgical mask if outside the room) [6] Citation 6. Siegel J, Rhinehart E, Jackson M, Chiarello L, and the Healthcare Infection Control Practices Advisory Committee. 2007 Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings. Published online July 2023.
  https://www.cdc.gov/infection-control/media/pdfs/Guideline-Isolation-H.pdf [Accessed April 28,2024].
• All patients: avoid contact with young children and pregnant women; avoid congregate settings including childcare, school, and work

 

Supportive care
Hydration and nutrition: if child is breastfeeding, continue; ensure adequate fluid and calorie intake, give frequent small feedings including after coughing bouts and post-tussive vomiting; some patients may require nasogastric tube feeding or IV maintenance fluids; be aware that NG tube placement might provoke paroxysmal coughing, so it should be inserted by experienced medical staff with minimal manipulation. If weight loss occurred during illness, consider food supplements for several weeks during convalescent stage when child is able to eat comfortably.

 

Respiratory measures

• Place the patient in a semi-reclining position (± 30°).
• In case of apnoea, stimulate the patient, but be prepared to ventilate if necessary (keep bag and mask accessible).
• Administer oxygen if SpO₂ < 92%, for severe respiratory distress, or for recurrent apnoea. Perform gentle oropharyngeal suctioning if required but avoid deep suctioning (may provoke paroxysmal coughing).

 

For children treated as outpatients, teach the parents about signs that require immediate medical attention (e.g. respiratory difficulty, apnoea, cyanosis, increasing fever, seizures or impaired consciousness, dehydration, feeding difficulty).

Contacts 

Prevention

• Pertussis vaccination provides substantial immunity that wanes over time [1] Citation 1. Pertussis vaccines: WHO position paper – August 2015. Wkly Epidemiol Rec. 2015;(35):433-458. https://iris.who.int/bitstream/handle/10665/242413/WER9035_433-458.PDF [Accessed May 17, 2024]. .
• In all cases (suspected cases and contacts) who are not up-to-date with pertussis vaccination, begin or refer for vaccination.
• Routine vaccination with a 3-dose primary series of polyvalent vaccine containing pertussis antigen(s) from the age of 6 weeks or according to national protocol. A booster dose is recommended, preferably during the second year of life [1] Citation 1. Pertussis vaccines: WHO position paper – August 2015. Wkly Epidemiol Rec. 2015;(35):433-458. https://iris.who.int/bitstream/handle/10665/242413/WER9035_433-458.PDF [Accessed May 17, 2024]. . Based on local epidemiology, further booster doses may be required later in life to reinforce immunity and reduce the risk of developing pertussis.
• If the pertussis primary vaccination series has been interrupted, it should be completed rather than restarted from the beginning.
• In general, vaccinations are deferred for patients with moderate to severe illness, but the vaccine should be administered as soon as the patient's condition has improved. 
• Vaccination will probably not prevent disease in a person who is already infected by B. pertussis. It is not a substitute for post-exposure prophylaxis [7] Citation 7. World Health Organization. Pertussis: Vaccine-Preventable Diseases Surveillance Standards. Published online September 5, 2018.
  https://www.who.int/publications/m/item/vaccine-preventable-diseases-surveillance-standards-pertussis [Accessed May 19, 2024]. [9] Citation 9. Blain A, Skoff T, Cassiday P, Tondella ML, Acosta A. Pertussis. In: Manual for the Surveillance of Vaccine-Preventable Diseases. Centers for Disease Control and Prevention; 2020:Chapter 10.
  https://www.cdc.gov/surv-manual/php/table-of-contents/chapter-10-pertussis.html [Accessed May 19, 2024]. .