Pertussis

FAQs for Health Care Providers

Pertussis Risk, Diagnosis, and Treatment in Afghan Evacuees

Pertussis is a highly contagious respiratory bacterial infection (Bordetella pertussis) that causes persistent, violent coughing that can impair the ability to breathe.

Have there been confirmed cases in the Afghan evacuees? At risk, but no confirmed cases

Epidemiology

Pertussis has been on the rise since the 1980’s due to a decrease in vaccination rates. Pertussis is responsible for 20-40 million deaths worldwide, most of whom are infants < 6 mo and adults with co-morbidities. Most pertussis infections around the world occur in Africa and Southeast Asia. The most commonly presenting age group is under 5 years. In Afghanistan, cases have been sporadic – in 2018, almost 500 cases were reported after only 1 case was reported between 2016-2017. This is likely very under-reported.

When should I consider pertussis?

Clinical Presentation

The classic sign/symptom of pertussis is often termed the “whooping cough”, which sometimes is followed by emesis (post-tussive emesis). The “whoop” is a high-pitched sound that occurs on inspiration after the spells of coughing. Of note, this whoop is typically absent in adolescents, adults, and those who are vaccinated. In infants, they may not be able to generate the “whoop” and they may have apnea alone as a presenting symptom. Vaccination does not preclude someone from being infected, though it tends to be milder.

There are 3 classic stages to pertussis:

  • Stage 1 – Catarrhal

    • Coryza (URI symptoms)

    • Low-grade fever

    • Mild cough

  • Stage 2 – Paroxysmal

    • Episodes of numerous rapid coughing

      • Often at night, average 15 attacks/24 hours

      • Increase in frequency for first 1-2 weeks, then plateaus for 2-3 weeks, then gradually decreases in frequency

    • Long inspiratory effort with “whoop” at the end of coughing episodes

    • Cyanosis

    • Vomiting

  • Stage 3 – Convalescent

    • Less persistent coughing over 2-3 weeks

Symptoms can present up to 3 weeks after exposure. The patients at highest risk are those who are unvaccinated or partially vaccinated and under 12 months of age.

Is pertussis contagious? Yes, extremely.

The R0 of pertussis (number of cases per index case) is about 16, which is similar to that of measles (much more than COVID19, which is under 3). It is spread through respiratory contact. Those infected after contagious up to 2 weeks after the cough begins. A fully vaccinated person can still be infected.

Are there special infectious disease precautions for someone with pertussis?

A person with suspected pertussis should be placed in contact (gloves, hand washing) and droplet (face mask) precautions. It is strongly encouraged to provide post-exposure prophylaxis (PEP) to people who may have been in contact with someone infected with pertussis. The dosing for PEP is the same as that for treatment. This specifically includes the following:

  • All household contacts of a case

  • High risk people within 21 days of exposure to a case

      • High risk people include infants, women in their third trimester of pregnancy, people with moderate to severe asthma, the immunocompromised, those in contact with the above

Please notify on-call Infectious Diseases for any suspect cases in Afghan evacuees, and pertussis is a reportable disease and all confirmed cases should be reported to the Minnesota Department of Health.

How do I diagnose pertussis?

Culture growing Bordetella pertussis is the gold standard, obtained with a nasopharyngeal specimen during the first 2 weeks of the cough. After the first 2 weeks, sensitivity of the test decreases. PCR testing is faster than culture, though can vary in specificity. Therefore, positive tests could be false and should therefore be confirmed with a culture. PCR testing can be done with a nasopharyngeal specimen during the first 4 weeks of infection.

Serology testing is also available and is best used during weeks 2-8 of illness. This form of testing is often used to assess for outbreaks and the accuracy in the clinical setting is currently unknown. See CDC for more information on testing.

What is the treatment for pertussis?

Treatment varies by age:

  • <1 month

        • Azithromycin 10mg/kg daily for 5 days

  • 1 – 5 months

        • Azithromycin 10mg/kg daily for 5 days

        • Erythromycin 40-50mg/kg/day in 4 divided doses for 14 days

        • Clarithromycin 15mg/kg/day in 2 divided doses for 7 days

  • Older children

        • Azithromycin 10mg/kg x1 on day 1, then 5mg/kg daily on days 2-5

        • Erythromycin 40-50mg/kg/day in 4 divided doses for 14 days

        • Clarithromycin 15mg/kg/day in 2 divided doses for 7 days

  • Adults

        • Azithromycin 500mg on day 1, then 250mg daily on days 2-5

        • Erythromycin 2g/day in 4 divided doses for 14 days

        • Clarithromycin 1g/day in 2 divided doses for 7 days

After an infection with pertussis, immunity is may wane and vaccination is still suggested.

Information on managing contacts, including post-exposure prophylaxis, can be found here.

Resources and References

Contributors

Andrew Wu, MD

Cindy Howard, MD

William Stauffer MD

FAQs pertussis.pdf