PCR: Best ≤3 weeks from cough onset; sensitivity ↓ after antibiotics or >3 weeks
Serology: Optimal after 2 weeks, up to 12 weeks (ideal <8 weeks)

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Effective Treatment: ≤3 weeks of cough onset; reduces transmission but not disease if delayed
Cough Duration: Up to 3 months, with prolonged convalescence

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First-Line:
- Azithromycin: 500 mg OD (Day 1), 250 mg OD (Days 2–5)
- Clarithromycin: 500 mg BD for 7 days
Alternative:
- TMP-SMX: Adults: 160+800 mg BD; Kids >1 month: 4+20 mg/kg BD (max 160+800 mg) for 7 days
- Neonates: Azithromycin 10 mg/kg OD for 5 days
Notes: Avoid roxithromycin; erythromycin poorly tolerated

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Prophylaxis:
- Who: Infants <6 months, pregnant women, high-risk contacts
- Antibiotics: Same as treatment, start ≤14 days post-exposure
Vaccination:
- Maternal: 20–32 weeks gestation
- dTpa boosters for adolescents/adults in close contact with infants
Public Health:
- Isolate ≥5 days after starting antibiotics
- Untreated: Infectious for 21 days post-cough onset

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Pertussis (Whooping Cough)

Diagnosis

Causative Organism: Bordetella pertussis
Symptoms: Cough >2 weeks with paroxysms, characteristic “whoop,” or post-tussive vomiting.
In Adults/Kids: May present as a persistent, non-specific cough.
Notification: Pertussis is a notifiable disease in Australia; report to public health authorities.

Testing

PCR
- Best if done ≤3 weeks from cough onset.
- Sensitivity falls after starting antibiotics or >3 weeks of cough.
Serology
- Ideal >2 weeks and <8–12 weeks from cough onset.
- May help confirm infection in subacute/chronic presentation.

Timing & Treatment

Effective Antibiotics: Start within 3 weeks of cough onset to reduce transmission, though may not alter the individual’s disease course if delayed.
Cough Duration: Can last up to 3 months, often called the “100-day cough.” Prolonged convalescence is common.

Antibiotics

First-Line

Azithromycin
- Adult: 500 mg orally Day 1, then 250 mg daily on Days 2–5
- Neonates (<1 month): 10 mg/kg daily for 5 days
Clarithromycin
- Adult: 500 mg BD for 7 days

Alternative

Trimethoprim-Sulfamethoxazole (TMP-SMX)
- Adult: 160+800 mg BD for 7 days
- Children >1 month: 4+20 mg/kg BD (max 160+800 mg) for 7 days

Notes

Prevention

Prophylaxis

Who needs prophylaxis?
- Infants <6 months, pregnant women, or high-risk close contacts
Same antibiotic regimens as for treatment, ideally started ≤14 days post-exposure

Vaccination

Public Health Measures

Notes

Emphasise hand hygiene and cough etiquette in preventing transmission
Suspect pertussis in prolonged cough especially if vaccination status incomplete or uncertain

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