Pertussis
Azithromycin is indicated for pertussis primarily to prevent transmission. When given early in illness it may reduce severity and shorten the course of illness.
Pertussis is described in three phases:
- Catarrhal - Upper respiratory infection like symptoms.
- Paroxysmal - Paroxysms of cough followed by an inspiratory whoop and frequently post-tussive emesis.
- Convalescent - Slow improvement of symptom over months.
In young infants the catarrhal phase may be brief. The characteristic whoop may be absents and gagging and apnea may be more prominent symptoms during the paroxysmal phase.
Antimicrobial therapy administered during the catarrhal stage may be effective in reducing severity while treatment in the paroxysmal phase will not modify disease process but remains indicated for prevention of spread.
Treatment is with a five day course of azithromycin which is less likely to cause pyloric stenosis than erythromycin. Clarithromycin and erythromycin are alternatives for children over one month of age and TMP/SMX is an alternative after two months of age.
Post exposure prophylaxis is indicated for household and other close contacts including other children in childcare even if vaccinated.
References:
Snyder J, Fisher D. Pertussis in childhood. Pediatr Rev. 2012 Sep;33(9):412-20; PMID: 2294236
American Academy of Pediatrics. Pertussis (Whooping Cough). In: Kimberlin DW, Brady MT, Jackson MA, Long SS, eds. Red Book: 2018 Report of the Committee on Infectious Diseases. American Academy of Pediatrics; 2018;