Infectious Disease - Whooping Cough

Question 1

Diagnosis

Answer 1

also known as pertussis , is an infectious disease caused by the gram-negative coccobacillus, Bordetella pertussis . It is spread by airborne droplets

Question 2

Disease progression

Answer 2

The incubation period of whooping cough is ~ 7 days.
The patient is infectious for 3 weeks after the onset of symptoms.

The disease usually follows three stages:
- Catarrhal
- Paroxysmal
- Convalescent

Question 3

Risk factors

Answer 3

Close contact with an infected individual
Lack of immunisation
Young children and infants

Question 4

Pathophysiology

Answer 4

B.pertussis adheres to the ciliated respiratory epithelium . It induces local inflammatory changes in the respiratory tract causing the characteristic cough. Bacteraemia does not occur, explaining why it is almost never found in blood cultures

Question 5

Symptoms

Answer 5

Catarrhal stage (1-2 weeks):
- dry, unproductive cough
- low grade fever
- conjunctivitis
- coryzal symptoms
Paroxysmal stage (1 week after catarrhal stage and lasts up to 6 weeks):
- coughing fits: typically consist of a short expiratory burst followed by an inspiratory gasp causing the whoop sound
- post-tussive vomiting
- children: gasping, cyanosis, apnoea, apparent life threatening event
Convalescent stage (lasts 1-2 weeks):
- gradual improvement of symptoms

Question 6

Diagnosis

Answer 6

• Nasopharyngeal swab/aspirate: sent for PCR = most appropriate test if cough is of 2-3 weeks or less
• Anti-pertussis toxin immunoglobulin G (IgG) serology: If Px over 17 years with Sx for more than 2 weeks.
  = Anti-pertussis toxin IgG detection in oral fluid can be used in children aged 5 to 16 years

Question 7

Treatment

Answer 7

FIRST LINE =
- Notify the local health protection team
- Hospital admission:
= < 6-months and acutely unwell
= Significant breathing problems, e.g. cyanosis
= Significant complication, e.g. seizure
- Abx:
= Onset of the cough is within 21 days = macrolide antibiotic = AZITHROMYCIN or CLARITHROMYCIN
- School/work absence until 48 hours of appropriate antibiotic treatment has been completed or 21 days after the onset of symptoms if antibiotics have not been given

Question 8

Contacts treatment

Answer 8

• Prophylactic antibiotic therapy: should be offered to certain close contacts of infected patients if the symptoms were experienced by the contact within the previous 21 days
• Immunisation: should be offered to all people who have been offered antibiotic prophylaxis

Question 9

Complications

Answer 9

Pneumonia
Encephalopathy
Otitis media
Injuries from coughing - pneumothorax, rib fractures or herniation of bowel (umbilical or inguinal)
Seizures from cerebral hypoxia during severe coughing episodes