Whooping cough/pertussis Flashcards
(14 cards)
Key points for whooping cough
Pertussis is a notifiable disease in Australia
Antibiotics reduce the severity of illness and risk of transmission if prescribed within the first 14 days of paroxysmal cough or 21 days of symptoms
Children are no longer infectious to others after 21 days into the illness, or after treatment with antibiotics for 5 days
Infants ≤6 months of age are at greatest risk of severe disease and complications
cause of whooping cough
Bordetella pertussis
What age group in pertussis is at the greatest risk of complications
less than or equal to 6 mo
incubation and infectious period whooping cough
Incubation period
Ranges from 4-21 days, usually 7-10 days
Infectious period
From onset of symptoms until the earliest of:
21 days after onset of symptoms,
14 days after onset of paroxysmal cough, or
completion of 5 days of appropriate antibiotics
Hx - whooping cough
Catarrhal phase (1-2 weeks): coryza and non-productive cough
Paroxysmal phase (1-2 weeks): episodes of paroxysmal coughing which peak after about a week
Classic paroxysms of coughing with inspiratory whoop and post-tussive vomiting are more commonly seen in unvaccinated children
Infants may develop apnoea, bradycardia or cyanosis with coughing spasms
Convalescent phase (2-6 weeks, may last up to 3 months): cough tapers off
During recovery, superimposed viral infections can trigger a recurrence of paroxysms
Can present as a non-specific persistent cough
Poor feeding, weight loss, sleep disturbance
Other family members frequently have a cough (>70% of household contacts are also infected)
Examination findings - whooping cough
Fever is uncommon
Clinical signs usually absent
Ix - suspected whooping cough
Laboratory confirmation is not necessary for diagnosis but may be helpful for infection control
A nasopharyngeal flocked swab for PCR is the investigation of choice (more sensitive than culture). The test is usually negative after 21 days, or 5-7 days after effective antibiotic therapy has been commenced
Culture (nasopharyngeal aspirate or swab) is the most specific test, and susceptibility testing can be done
Culture is recommended for:
catarrhal phase
early paroxysmal phase
severe cases requiring admission
suspected treatment failure
request by public health unit
Pertussis serology is not clinically useful
Supporting laboratory testing:
blood tests should not be routinely performed
degree of lymphocytosis correlates with severity of disease
thrombocytosis is common and correlates with poorer prognosis in infants
CXR is only indicated in unwell infants <6 months old (rare risk of B pertussis pneumonia with associated pulmonary hypertension)
When are cultures of nasopharygneal aspirate or swab recommended for in pertussis
catarrhal phase
early paroxysmal phase
severe cases requiring admission
suspected treatment failure
request by public health unit
When is CXR indicated in whooping cough
in unwell infants <6 months old (rare risk of B pertussis pneumonia with associated pulmonary hypertension)
Indications for tx of whooping cough
Indications include
diagnosis in catarrhal or early paroxysmal phase (may reduce severity)
cough for <14 days or symptoms for <21 days (may reduce spread and school exclusion period)
hospital admission
severe symptoms or complications as above
Tx of whoooping cough
Azithromycin
<6 months old: 10 mg/kg oral daily for 5 days
≥6 months old: 10 mg/kg (max 500 mg) oral daily on day 1, then 5 mg/kg (max 250 mg) daily on days 2-5
or
Clarithromycin
≥1 month old: 7.5 mg/kg (max 500 mg) oral bd for 7 days
If macrolides are contraindicated, or B pertussis is resistant to macrolides: Trimethoprim/sulfamethoxazole (8/40 mg/mL)
> 2 months old: 0.5 mL/kg (max 20 mL) oral bd for 7 days
Erythromycin is not recommended due to the risk of pyloric stenosis in infants
admission criteria whooping cough
Consider admission for:
all infants <6 months given risk for rapid deterioration
respiratory distress
inability to feed
evidence of pneumonia
cyanosis or apnoea, with or without coughing
seizures
Droplet precautions are required
Isolation and school/childcare exclusion whooping coug
21 days after onset of symptoms
14 days after onset of paroxysmal cough
completion of 5 days of appropriate antibiotics
Mng of contacts - whooping cough
https://www.rch.org.au/clinicalguide/guideline_index/Whooping_Cough_Pertussis/#management-of-contacts
