Pertussis is now more common in older children and adults with waning immunity. The greatest risk of the disease is in those with small airways, especially < 6 months age (hence the rationale for a “cocooning” strategy to protect newborns), related to thick inspissated mucus and apnoea, severe pneumonia, and encephalopathy.
Clinical manifestations include:
- often no clinical signs – well between coughing spasms
- can present as non-specific, persistent cough
- vomiting often follows a coughing spasm
- infants may have apnoea / cyanosis with coughing spasms
- any contacts: infectious just before and for 21 days after onset of cough
- > 70% household contacts also infected
- fever is uncommon
- can occur in immunised, but illness generally less severe
- nasopharyngeal PCR usually negative after 21 days (or 5-7 days of antibiotics)
Management of a pertussis case:
Neonate
- azithromycin 10 mg / kg PO daily x 5 days
Child
- clarithromycin liquid 7.5 mg / kg / dose PO twice daily x 7 days
OR
- azithromycin 10 mg / kg PO Day 1
- then 5 mg / kg PO daily x Days 2 – 5
OR, if macrolide contraindicated
- trimethoprim-sulphamethoxazole [8 mg ¦ 40 mg per mL]
- 0.5 mL/ kg (max. 20 mL) PO twice daily x 7 days
Exclude the child from school and the presence of others outside the home (especially infants, young children) until they have received 5 days of treatment, or have been coughing for > 21 days. Antibiotic prophylaxis should be given to household contacts.