Severe Atypical Bacterial & Parasitic Infections

Pertussis (Whooping Cough)

Acute Bacterial Toxin-Mediated Airway Infection

Primary risk age: Infants under 6 months (Highest risk for severe complications; unvaccinated children)

Urgency: Severe
Typical age: Infants under 6 months (Highest risk for severe complications; unvaccinated children)
Body system: Infectious & Parasitic

Typical course: Convalescent stage lasts weeks to months (often called the "100-day cough") as the respiratory cilia slowly regenerate.

Reviewed against AAP · CDC · WHO · NHS guidance Last reviewed 2026-06-13

1. Summary & Pathophysiology

Acute Bacterial Toxin-Mediated Airway Infection

Pathophysiology (Development Path)

The bacteria colonize the ciliated respiratory epithelium, producing toxins (pertussis toxin, tracheal cytotoxin) that paralyze the cilia and trigger localized inflammation. This leads to impaired mucus clearance, necrosis of epithelial cells, and severe, spasmodic coughing fits.

Primary Causes & Etiology

Bordetella pertussis (a Gram-negative, fastidious coccobacillus).

2. Symptom Continuum

Early Onset Signs
Catarrhal stage (lasts 1-2 weeks): mild upper respiratory symptoms including rhinorrhea, sneezing, low-grade fever, and a mild, occasional cough.
Progressive Phase
Paroxysmal stage (lasts 2-6 weeks): severe coughing fits (paroxysms) occurring 15-30 times a day. The child coughs repeatedly on a single expiration, followed by a forced inspiratory "whoop" sound as they gasp for air. Post-tussive vomiting (vomiting after coughing) is highly characteristic.
Severe Indicators
In infants: coughing fits may be absent; instead, they present with apnea, cyanosis (turning blue), bradycardia, seizures, and severe exhaustion.

3. Clinical Verification

Nasopharyngeal swab culture (gold standard but slow) or PCR assay for Bordetella pertussis DNA.

4. Care & Elements Plan

Primary Care Treatment Plan

Administer macrolide antibiotics early in the course (catarrhal stage) to shorten the disease. Prophylaxis is indicated for all household contacts. Hospitalize infants under 6 months for monitoring of apnea and airway support.

Home Support Elements

Use a cool-mist humidifier to help loosen secretions. Keep the home free of irritants (smoke, dust). Offer small, frequent meals to prevent vomiting after coughing fits.

Generic Active Ingredients (No Brands)

Azithromycin or Erythromycin (generic macrolide antibiotic active ingredients used to eradicate B. pertussis and reduce transmission). Cough suppressants are not recommended.

Lists active elements only. Never administer self-designed therapies.

5. Doctor Critical Lines

Critical Thresholds: When to See a Doctor

Any infant showing gasping, pauses in breathing (apnea), or turning blue during coughing fits requires immediate emergency medical evaluation.

6. Vaccine & Prevention

Routine Prophylaxis (Prevention)

Post-exposure antibiotic prophylaxis for all close contacts regardless of vaccination status.

Immunization Context

Prevented through the DTaP vaccine series in childhood (at 2, 4, 6, 15-18 months, and 4-6 years) and Tdap booster in adolescence. Maternal vaccination during pregnancy provides passive immunity to newborns.

7. Timelines & Outlook

Active Timeline

Convalescent stage lasts weeks to months (often called the "100-day cough") as the respiratory cilia slowly regenerate.

Expected Prognosis

Excellent for older children. It is a severe, high-mortality disease in young infants under 2 months who have not received their first vaccine dose.

Potential Untreated Complications

Pneumonia (most common), hypoxic encephalopathy, seizures, subconjunctival hemorrhages, rib fractures, and death in young infants.

Severe

Congenital Toxoplasmosis

Perinatal Protozoan Opportunistic Infection

Neonates (Infection acquired in utero)

Moderate

Scarlet Fever (Scarlatina)

Toxin-Mediated Streptococcal Exanthem

5 to 15 Years