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Toronto Notes 2019 Infectious Diseases Pertussis
Definition
• prolongedrespiratoryillnesscharacterizedbyparoxysmalcoughingandinspiratory“whoop”
Epidemiology
• ~10millionchildren<1yroldaffectedworldwide,causesupto400,000deaths/yr
• greatestincidenceamongchildren<1yr(notfullyimmunized)andadolescents(waningimmunity)
Etiology
• Bordetellapertussis:Gramnegativepleomorphicrod
• highlycontagious;transmittedviarespiratorydropletsreleasedduringintensecoughing
• incubationperiod:6-20d;mostcontagiousduringcatarrhalphasebutmayremaincontagiousfor
weeks after
History
• prodromalcatarrhalstage
■ lasts 1-7 d; URTI symptoms (coryza, mild cough, sneezing) with NO or LOW-GRADE fever
• paroxysmalstage
■ lasts 4-6 wk; characterized by paroxysms of cough (“100 day cough”), sometimes followed by
inspiratory whoop (“whooping cough”)
■ infants <6 mo may present with post-tussive apnea, whoop is often absent
■ onset of attacks precipitated by yawning, sneezing, eating, physical exertion
■ ± post-tussive emesis, may become cyanotic before whoop ■ vomiting after whooping episodes
• convalescentstage
■ lasts 1-2 wk; characterized by occasional paroxysms of cough, but decreased frequency and severity ■ non-infectious but cough may last up to 6 mo
Investigations
• NPspecimenusingaspirateorNPswab
■ gold standard: culture using special media (Regan-Lowe agar) ■ PCR to detect pertussis antigens
• bloodwork:CBC(lymphocytosis)andserology(antibodiesagainstB.pertussis)
Management
• admitifparoxysmsofcoughareassociatedwithcyanosisand/orapneaandgiveO2
• supportivecare
• antimicrobialtherapyindicatedifB.pertussisisolated,orsymptomspresentfor<21d
■ use macrolide antibiotics (azithromycin, erythromycin, or clarithromycin) • dropletisolationuntil5doftreatmentandreporttoPublicHealth
• prophylaxis
■ macrolide antibiotics for all household contacts
■ prevention with vaccination in infants and children (Pentacel®), and booster in adolescents
(Adacel®) (see Routine Immunization, P4)
Complications
• pressure-relatedfromparoxysms:subconjunctivalhemorrhage,rectalprolapse,hernias,epistaxis
• respiratory: sinusitis, pneumonia, aspiration, atelectasis, pneumomediastinum, pneumothorax, alveolar
rupture
• neurological:seizures(~3%),encephalopathy,ICH
• mortality:~0.3%;highestriskininfants<6moold
Pneumonia
• seeRespirology,P69
Periorbital (Preseptal) and Orbital Cellulitis
• seeOphthalmology,OP9
Sexually Transmitted Infections
• seeFamilyMedicine,FM42andGynecology,GY26
Pediatrics P57
Cardinal Signs of Orbital Cellulitis
• Ophthalmoplegia/diplopia
• Decreased visual acuity
• Pain with extraocular eye movement