What is the diagnosis and treatment for a 3-year-old boy with recurrent coughing episodes followed by a high-pitched noise, suggestive of a whoop, and incomplete immunizations?

Diagnosis: Pertussis (Whooping Cough)

This 3-year-old with recurrent paroxysmal coughing episodes followed by a high-pitched inspiratory noise (whoop) and incomplete immunizations has pertussis and should be treated immediately with azithromycin. 1, 2

Clinical Diagnosis

The diagnosis of pertussis in this child is based on the following key clinical features:

• Paroxysmal cough: Recurrent prolonged coughing episodes lasting two weeks meet the clinical case definition 1
• Inspiratory whooping: The high-pitched noise after coughing episodes is the classic "whoop" sound, which is highly specific (77.7%) for pertussis in children 1
• Incomplete immunizations: This significantly increases risk for pertussis infection and more severe disease 1, 2
• Normal vital signs and physical exam: Typical for pertussis, as the disease is primarily diagnosed clinically rather than by physical findings 1

In children with acute cough (<4 weeks), the presence of paroxysmal cough or inspiratory whooping should prompt consideration of pertussis as the diagnosis. 1

Treatment Approach

Antibiotic Therapy

• Azithromycin is the preferred first-line agent for treating pertussis in children 2, 3
• Treatment should be initiated immediately based on clinical diagnosis without waiting for laboratory confirmation 1
• Early antibiotic administration can reduce symptom duration and severity and decrease the period of communicability to others 2
• Macrolide antibiotics are the treatment of choice regardless of disease stage 3

Expected Clinical Course

• The paroxysmal phase typically persists for 2-6 weeks, with coughing episodes increasing in frequency and severity initially 2
• Coughing episodes occur more frequently at night 2
• Post-tussive vomiting is common in children with pertussis 1, 2
• The cough may persist for much longer during the convalescent phase, sometimes earning the nickname "hundred day cough" 1

Infection Control and Prevention

Household and Close Contacts

• All close contacts should receive post-exposure prophylaxis with macrolide antibiotics within 21 days of exposure 3
• This is particularly critical for household contacts and those at high risk of severe disease (infants, pregnant women, immunocompromised individuals) 3

Isolation Precautions

• Respiratory droplet precautions should be maintained until 5 days of appropriate antibiotic treatment are completed 3
• The organism is highly contagious, with one active case potentially infecting 70-100% of household contacts 1

Vaccination

• Complete the DTaP vaccination series as this child's immunizations are not up-to-date 2, 3
• DTaP is recommended at ages 2,4,6,15-18 months, and 4-6 years 2
• Vaccination is the most effective preventive strategy against pertussis 2, 3

Laboratory Confirmation (Optional but Recommended)

While treatment should not be delayed for laboratory results, confirmation is useful for:

• PCR testing from nasopharyngeal secretions: Rapid, highly specific, with sensitivity of 80-100% 1
• Culture: Requires enriched media, sensitivity only 25-50%, but highly specific 1
• Reporting to public health authorities: Both probable and confirmed cases should be reported 1

Critical Pitfalls to Avoid

• Do not delay treatment waiting for laboratory confirmation - pertussis is a clinical diagnosis and early treatment is essential 1, 2
• Do not assume antibiotics are ineffective - while they may not dramatically shorten symptoms if given late, they are critical for reducing transmission 2, 3
• Do not forget to treat close contacts - adults are the main reservoir for pertussis today and often transmit to children 1, 4
• Do not overlook the need for respiratory isolation - pertussis is highly contagious via respiratory droplets 3