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id.pertussis.v1PRODUCTION
id.pertussis.v1

Pertussis (whooping cough) — Bordetella pertussis — catarrhal + paroxysmal + convalescent phases + infant pertussis (apnea, pneumonia, pulmonary hypertension) + adult atypical + post-exposure prophylaxis + maternal Tdap at 27-36 wk every pregnancy + DTaP/Tdap vaccination schedule + cocooning

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Canonical 12-phase frame with authored status for this dossier.

Current phase

Frame

Detailed

Pertussis spectrum: catarrhal phase 1-2 wk (URI-like; MOST CONTAGIOUS) + paroxysmal phase 2-6 wk (paroxysms + whoop + post-tussive emesis + apnea infants) + convalescent phase weeks-months ("100-day cough") + infant pertussis high-mortality phenotype (apnea + pneumonia + pulmonary hypertension from WBC > 100,000 leukostasis + seizures + encephalopathy + death) + adult atypical pertussis (chronic cough > 2 wk + paroxysms in waning-immunity host) + post-exposure prophylaxis (azithromycin within 21 d of cough onset) + maternal Tdap (27-36 wk every pregnancy regardless of prior status) + DTaP routine pediatric series + Tdap adolescent + adult every 10 yr + cocooning (Cherry Pediatrics 2005 PMID 15876920; CDC pertussis; AAP Red Book 2024; Liang MMWR 2018 PMID 29702631)

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Pertussis phenotype framed (catarrhal / paroxysmal / convalescent / infant / adult atypical / post-exposure / vaccination-eligible) and public-health-emergency posture activated

Patient inputs (18)

Age stratifies macrolide selection (azithromycin preferred in < 1 mo per AAP — erythromycin pyloric stenosis ~ 7× background risk per Honein Lancet 1999 PMID 10609814 + Eberly Pediatrics 2015 PMID 25687145; TMP/SMX > 2 mo only), admission threshold (low for < 6 mo), phenotype prediction (infant = apnea + pneumonia + pulmonary hypertension; adult = atypical chronic cough + paroxysms), and DTaP/Tdap schedule eligibility (pediatric 2/4/6/15-18 mo + 4-6 yr; adolescent 11-12 yr; adult every 10 yr)

DTaP / Tdap dose history determines susceptibility status, waning immunity (5-10 yr post-completion per Klein NEJM 2012 PMID 22970945), maternal Tdap need (27-36 wk every pregnancy per ACIP every pregnancy regardless of prior status), adolescent booster need (11-12 yr), adult every 10 yr need, cocooning need for close contacts of newborns (Liang MMWR 2018 PMID 29702631)

Index case + exposure timing (within 21 d of cough onset → PEP azithromycin); secondary attack rate ~ 80-100% in unvaccinated household contacts; outbreak context (community pertussis outbreak underway → multiplies pre-test probability 5-20× for any prolonged paroxysmal cough); cohort isolation if institutional outbreak (CDC pertussis)

Pregnancy at 27-36 wk gestation → Tdap every pregnancy regardless of prior Tdap status per ACIP (most powerful upstream prevention of neonatal pertussis); active pertussis in pregnancy → azithromycin within 21 d of cough onset + maternal-fetal medicine consult + PEP for household contacts; Tdap is Category B safe in pregnancy (Skoff CID 2017 PMID 29028938; ACOG; ACIP)

Continuous cardiopulmonary monitoring in infants < 6 mo with pertussis — apnea may be the only feature; cyanosis during paroxysm + post-paroxysm exhaustion; SpO2 + respiratory rate + apnea alarms (AAP Red Book 2024)

Paroxysmal cough lasting > 2 wk + (post-tussive emesis OR inspiratory whoop) + inter-paroxysm well-appearance → near-pathognomonic clinical diagnosis; inspiratory whoop more reliable in children; absent in many adults + infants where apnea may be only feature (Cherry Pediatrics 2005 PMID 15876920; AAP Red Book 2024)

Cough onset time defines phase (catarrhal 0-2 wk + paroxysmal 2-6 wk + convalescent > 6 wk) + treatment window (within 21 d of cough onset for treatment + PEP) + contagious window (catarrhal phase most contagious + droplet isolation until 5 d of effective antibiotic or 21 d of cough if untreated) (CDC pertussis; AAP Red Book 2024)

CBC with differential — lymphocytosis (WBC 20,000-50,000 with marked lymphocyte predominance) is characteristic of pertussis especially in young children; **WBC > 100,000 with lymphocyte predominance** signals leukostasis + pulmonary hypertension risk → ICU + exchange transfusion or leukapheresis considered; adolescents + adults often without prominent lymphocytosis (Cherry Pediatrics 2005; AAP Red Book 2024)

PCR (preferred 1st 3 wk of cough; sens 90-95% / spec 95-99%) — nasopharyngeal swab (deep — not anterior nares); specific Bordetella pertussis primer panel preferred over multiplex respiratory panel; consider both species-specific PCR for B. pertussis and B. parapertussis (CDC pertussis; AAP Red Book 2024)

Apnea + cyanosis without preceding paroxysm in infant < 6 mo = potentially pertussis-driven; life-threatening; cardiopulmonary monitoring + ICU consideration; cross-route to peds.brue.v1 for BRUE / ALTE differential framework; mortality 1-2% in infants < 6 mo (AAP Red Book 2024; CDC pertussis)

SpO2 < 94% in pertussis + cough / dyspnea / new infiltrates → pertussis pneumonia (primary B. pertussis pneumonia OR bacterial superinfection); empiric ceftriaxone ± vancomycin per IDSA HAP/CAP + continue azithromycin (AAP Red Book 2024; IDSA/ATS CAP 2019)

HIV (CD4 < 200), transplant (within 1 yr OR ongoing immunosuppression), chemo (cycle nadir), high-dose chronic steroid (≥ 20 mg prednisone-equivalent × ≥ 1 mo), autoimmune on biologic — raise atypical-presentation + prolonged-shedding risk; lower admission threshold; cross-route to id.opportunistic-infection.hiv-transplant.v1 in some cases (AAP Red Book 2024)

Baseline + serial in immunocompromised or pregnant; for azithromycin QT-prolongation risk (baseline QT) + for TMP/SMX hyperkalemia / AKI monitoring; for IV hydration adequacy (FDA labels)

Procalcitonin > 0.25 ng/mL in pertussis + new fever spike / focal consolidation → bacterial superinfection — empiric ceftriaxone ± vancomycin (IDSA/ATS CAP 2019)

CXR if respiratory features — pertussis pneumonia (primary B. pertussis pneumonia = diffuse interstitial infiltrates; bacterial superinfection = focal consolidation); guides empiric antibiotic decision (AAP Red Book 2024; IDSA/ATS CAP 2019)

LP + CSF cell count + protein + glucose + bacterial culture + Gram stain if encephalopathy / seizures; usually nonspecific in pertussis encephalopathy (rule out bacterial meningitis + viral encephalitis); empiric IV acyclovir for HSV differential per institutional protocol if clinical concern (AAP Red Book 2024)

IgG-PT (IgG to pertussis toxin) serology — acute + convalescent samples; sens ~ 75-90% in late phase ≥ 2 wk of cough; use IgG-PT specifically not anti-FHA which cross-reacts with other Bordetella + parapertussis; consistent with vaccination response so interpret in context (CDC pertussis)

Culture (gold standard but slow 7-10 d + insensitive after 2 wk of cough); usually deferred to PCR + serology; reserved for outbreak surveillance + antimicrobial susceptibility testing (CDC pertussis)

* = hard-required. Engine cannot meaningfully run until these are filled.

Severity triggers (10)

10 need judgement
  • informationallife_threateninginfant_under_6mo_with_pertussis
    Infant < 6 mo with confirmed/suspected pertussis (any phase: catarrhal, paroxysmal, convalescent) — life-threatening; admit (cardiopulmonary monitoring for apnea — apnea may be the only feature; whoop and post-tussive emesis often absent in infants); supportive (O2, NIV, ICU as needed); azithromycin first-line (10 mg/kg/d PO × 5 d; NEVER erythromycin < 1 mo per AAP — hypertrophic pyloric stenosis ~ 7× background risk per Honein Lancet 1999 PMID 10609814 + Eberly Pediatrics 2015 PMID 25687145); ID consult; STAT public health notification (CDC pertussis; AAP Red Book 2024)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationallife_threateningapnea_in_pertussis_infant
    Apnea episodes in infant pertussis (may precede or replace classic paroxysms; whoop and post-tussive emesis often absent) — life-threatening; ICU + continuous cardiopulmonary monitoring + apnea alarms; supplemental O2 + NIV / mechanical ventilation if severe; mortality 1-2% in infants < 6 mo developed-world (up to 5-10% developing world); cross-route to peds.brue.v1 for BRUE / ALTE differential framework — pertussis must be ruled out before BRUE diagnosis (AAP Red Book 2024; CDC pertussis)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationallife_threateningencephalopathy_or_seizures
    Pertussis encephalopathy (~ 0.3-1%) or seizures (~ 2%) — life-threatening; admit ICU + supportive + neurology + EEG + MRI + LP + CSF studies (rule out bacterial meningitis + viral encephalitis); anoxic + hypoxic + direct-toxin etiologies; substantial mortality + permanent neurologic sequelae; continue azithromycin for pertussis; cross-route to id.bacterial-meningitis.core.v1 / .peds.v1 via workup.first_seizure for differential framework (AAP Red Book 2024; CDC pertussis)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverepneumonia_complication
    Pertussis pneumonia (primary B. pertussis pneumonia OR bacterial superinfection — MRSA, S. pneumoniae, S. aureus, H influenzae) — severe; admit (ICU if respiratory failure); supportive O2 ± ventilation; **continue azithromycin** for pertussis + **add empiric ceftriaxone ± vancomycin** per IDSA HAP/CAP if bacterial superinfection features (focal consolidation, procalcitonin > 0.25, leukocytosis with neutrophil predominance, clinical deterioration); cross-route to pulm.cap.core.v1 (AAP Red Book 2024; IDSA/ATS CAP 2019; IDSA HAP/VAP 2016)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalseverepublic_health_notification
    ANY suspected/confirmed pertussis case → IMMEDIATE notification of state/local public health (do NOT wait for laboratory confirmation) + droplet isolation + outbreak investigation + contact tracing (close contacts within 21 d of cough onset of index case); every pertussis case is a notifiable disease per CDC + state law; cohort isolation if institutional outbreak (school, childcare, healthcare) (CDC pertussis; state notifiable-disease law)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereunvaccinated_or_partially_vaccinated_child_outbreak
    Unvaccinated or partially vaccinated child (< 5 DTaP doses) in pertussis outbreak context (community, school, childcare, healthcare) → severe; **catch-up DTaP per ACIP catch-up schedule** + cocooning strategy for household contacts + close-contact monitoring + cohort isolation if school / childcare outbreak; STAT public health notification (CDC pertussis; AAP Red Book 2024; ACIP)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereerythromycin_neonatal_pyloric_stenosis_risk
    Infant < 1 mo with pertussis → AVOID ERYTHROMYCIN per AAP — hypertrophic pyloric stenosis ~ 7× background risk per Honein Lancet 1999 PMID 10609814 + Eberly Pediatrics 2015 PMID 25687145 + subsequent cohorts; **USE AZITHROMYCIN** (10 mg/kg/d × 5 d) — lower but still elevated pyloric stenosis risk than erythromycin (~ 2-3× background); monitor for vomiting post-azithromycin in neonates (CDC pertussis; AAP Red Book 2024; Tiwari MMWR 2005 PMID 16340941)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatehousehold_close_contact_prophylaxis
    Household / school / healthcare / childcare close contact within 21 d of cough onset of confirmed/suspected pertussis index case → **azithromycin same dose as treatment** (10 mg/kg/d × 5 d infant; 10 mg/kg day 1 then 5 mg/kg × 4 d child/adolescent; 500 mg day 1 then 250 mg × 4 d adult) for all close contacts regardless of vaccination status; especially urgent for high-risk contacts (infants < 12 mo, pregnant 3rd trimester, immunocompromised, HCW caring for infants); cocooning concept for close contacts of newborns (Tiwari MMWR 2005 PMID 16340941; CDC pertussis; AAP Red Book 2024)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderateolder_child_atypical_presentation
    Adolescent or adult with chronic cough > 2 wk + paroxysms + post-tussive emesis + inter-paroxysm well-appearance + waning DTaP / Tdap immunity at 5-10 yr post-completion → atypical pertussis often missed; **PCR (preferred 1st 3 wk; sens 90-95%) + IgG-PT serology (acute + convalescent — late phase ≥ 2 wk; sens 75-90%) + culture optional** (gold standard but slow + insensitive after 2 wk); **azithromycin within 21 d of symptom onset** reduces transmission with limited symptom benefit in paroxysmal phase; reinforces need for adult Tdap every 10 yr (Cherry Pediatrics 2005 PMID 15876920; Klein NEJM 2012 PMID 22970945; CDC pertussis)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmildmaternal_tdap_vaccination_at_27_36wk
    Pregnancy at 27-36 weeks gestation → **Tdap 0.5 mL IM regardless of prior Tdap status per ACIP every pregnancy**; most powerful upstream prevention of neonatal pertussis — protective antibodies transfer placentally to neonate before primary DTaP series completes; reduces infant pertussis hospitalization ~ 78-91%; Category B safe in pregnancy; cocooning Tdap for close contacts of newborn synergistic (Skoff CID 2017 PMID 29028938; Skoff CID 2017 PMID 29028938; Liang MMWR 2018 PMID 29702631; ACOG; ACIP)
    Trigger could not be auto-evaluated — needs clinician judgement.

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Recommended regimen

Pertussis azithromycin treatment (first-line all ages incl. < 1 mo) + erythromycin alternative > 1 mo + TMP/SMX alternative > 2 mo + PEP azithromycin for close contacts within 21 d + empiric bacterial co-empirics for superinfection + supportive care + maternal Tdap at 27-36 wk every pregnancy + DTaP routine pediatric series + Tdap adolescent + adult every 10 yr + cocooning
axis: pertussis_treatment_and_pep_and_vaccinationstep azithromycin_first_line_treatment_all_ages - Azithromycin first-line for pertussis treatment all ages including < 1 mo (per AAP — preferred over erythromycin due to pyloric stenosis risk)
Selected step "Azithromycin first-line for pertussis treatment all ages including < 1 mo (per AAP — preferred over erythromycin due to pyloric stenosis risk)" — Confirmed or suspected pertussis case within 21 d of cough onset (catarrhal or paroxysmal phase); any age including < 1 mo
  • azithromycin
    first line
    macrolide
    Infant < 6 mo: 10 mg/kg PO daily × 5 d; Infant 6 mo+ / child / adolescent: 10 mg/kg day 1 (max 500 mg) then 5 mg/kg × 4 d (max 250 mg); Adult: 500 mg day 1 then 250 mg PO daily × 4 d • PO • daily × 5 d
    triggers: pertussis_within_21d_cough_onset, pep_close_contact_within_21d_cough_onset
    First-line per CDC pertussis + AAP Red Book 2024 + Tiwari MMWR 2005 PMID 16340941; short 5-d course; better tolerated than 14-d erythromycin per Altunaiji Cochrane 2007 PMID 17636756; preferred in < 1 mo per AAP — hypertrophic pyloric stenosis ~ 2-3× background risk (lower than erythromycin ~ 7×); monitor for vomiting in neonates post-azithromycin
    rxcui 18631

outpatient playbook — drug actions (8)

  1. 1. azithromycin (first-line all ages)
    Infant < 6 mo: 10 mg/kg PO daily × 5 d; Infant 6 mo+ / child / adolescent: 10 mg/kg day 1 (max 500 mg) then 5 mg/kg × 4 d; Adult: 500 mg day 1 then 250 mg × 4 d • PO • daily × 5 d
    trigger: Confirmed/suspected pertussis within 21 d of cough onset
    First-line per CDC pertussis + AAP Red Book 2024
  2. 2. erythromycin (alternative > 1 mo)
    Pediatric > 1 mo: 40-50 mg/kg/d PO divided q6h × 14 d; Adult: 500 mg PO q6h × 14 d • PO • q6h × 14 d
    trigger: Age > 1 mo + azithromycin unavailable or contraindicated
    Erythromycin alternative > 1 mo per CDC; CONTRAINDICATED < 1 mo per pyloric stenosis risk
  3. 3. TMP/SMX (alternative > 2 mo if macrolide-intolerant)
    Pediatric > 2 mo: 8 mg/kg/d TMP component PO divided q12h × 14 d; Adult: TMP 160 mg / SMX 800 mg PO q12h × 14 d • PO • q12h × 14 d
    trigger: Age > 2 mo + macrolide intolerance / contraindication; NOT in late pregnancy
    TMP/SMX alternative > 2 mo per CDC; CONTRAINDICATED late pregnancy + < 2 mo per kernicterus / hyperbilirubinemia
  4. 4. acetaminophen (fever / pain)
    Pediatric 10-15 mg/kg/dose q4-6h PRN (max 75 mg/kg/d); adult 500-1000 mg q6h PRN (max 4 g/d) • PO • q4-6h PRN
    trigger: Fever or pain
    Antipyretic + analgesic
  5. 5. PEP azithromycin (close contact within 21 d)
    Same dose as treatment per age • PO • daily × 5 d
    trigger: Close contact (household, school, healthcare, childcare) within 21 d of cough onset of index case
    PEP same dose as treatment per Tiwari MMWR 2005 PMID 16340941 + CDC pertussis
  6. 6. Tdap (maternal at 27-36 wk gestation)
    0.5 mL IM • IM • single dose at 27-36 wk gestation
    trigger: Pregnancy at 27-36 wk regardless of prior Tdap status
    Most powerful upstream prevention of neonatal pertussis per Skoff CID 2017 PMID 29028938 + Skoff CID 2017 PMID 29028938; every pregnancy per ACIP regardless of prior Tdap
  7. 7. DTaP (routine pediatric 5-dose)
    0.5 mL IM × 5 doses • IM • 2, 4, 6, 15-18 mo + 4-6 yr
    trigger: Routine pediatric immunization
    Liang MMWR 2018 PMID 29702631 + ACIP
  8. 8. Tdap (adolescent booster + adult every 10 yr + cocooning)
    0.5 mL IM • IM • Adolescent 11-12 yr; adult Tdap once + Td or Tdap every 10 yr; cocooning single dose for close contact of newborn
    trigger: Adolescent booster + adult catch-up + cocooning for close contacts of newborns
    Liang MMWR 2018 PMID 29702631 + ACIP; cocooning synergistic with maternal Tdap per Skoff CID 2017 PMID 29028938

Auto-drafted A&P note

outpatient

Subjective

- Possible entry pathways: Paroxysmal cough lasting > 2 wk + inspiratory whoop OR post-tussive emesis + inter-paroxysm well-appearance — pathognomonic pertussis paroxysmal phase (Cherry Pediatrics 2005 PMID 15876920; AAP Red Book 2024); Catarrhal phase (1-2 wk) URI-like (coryza, mild cough, low-grade fever) + outbreak / exposure context — MOST CONTAGIOUS phase; treatment within this window dramatically reduces transmission (Cherry Pediatrics 2005; CDC pertussis); Apnea / cyanosis in infant < 6 mo (paroxysmal cough may be absent or minimal) — high mortality infant phenotype; cardiopulmonary monitoring + azithromycin + ICU consideration (AAP Red Book 2024; CDC pertussis).

Objective

- No vitals, labs, or imaging entered for this encounter.

Assessment

**Pertussis (whooping cough) — Bordetella pertussis — catarrhal + paroxysmal + convalescent phases + infant pertussis (apnea, pneumonia, pulmonary hypertension) + adult atypical + post-exposure prophylaxis + maternal Tdap at 27-36 wk every pregnancy + DTaP/Tdap vaccination schedule + cocooning** (id.pertussis.v1).
Phenotype framing: Pertussis vs viral URI / common cold (pertussis paroxysms + whoop + post-tussive emesis + inter-paroxysm well-appearance distinguish; URI more uniform + shorter); RSV bronchiolitis in infants (RSV wheeze + tachypnea + retractions + diffuse crackles; pertussis paroxysms + apnea + cyanosis + lymphocytosis; RSV PCR distinguishes; can co-exist); other Bordetella (B. parapertussis milder; B. holmesii adolescent / young-adult; PCR species-specific primers distinguish); adenovirus (conjunctivitis + pharyngitis + fever + lymphadenopathy); Mycoplasma pneumonia (interstitial infiltrate + low-grade fever + extra-pulmonary features); Chlamydia pneumoniae (subacute pneumonia + sore throat + hoarseness); tuberculosis (weight loss + cavitary infiltrate + AFB / GeneXpert); asthma / cough-variant asthma (wheeze + reversibility on spirometry); GERD in infants (post-prandial regurgitation + arching); foreign body aspiration in toddlers (sudden choking + asymmetric breath sounds); infant pertussis with apnea vs RSV / sepsis / BRUE (pertussis paroxysmal cough phase + lymphocytosis + exposure; RSV wheeze + URI; sepsis fever + toxic + neutrophilic leukocytosis; BRUE excludes diagnosable etiology — pertussis must be ruled out before BRUE diagnosis) (Cherry Pediatrics 2005; AAP Red Book 2024)
Scope: Pertussis spectrum: catarrhal phase 1-2 wk (URI-like; MOST CONTAGIOUS) + paroxysmal phase 2-6 wk (paroxysms + whoop + post-tussive emesis + apnea infants) + convalescent phase weeks-months ("100-day cough") + infant pertussis high-mortality phenotype (apnea + pneumonia + pulmonary hypertension from WBC > 100,000 leukostasis + seizures + encephalopathy + death) + adult atypical pertussis (chronic cough > 2 wk + paroxysms in waning-immunity host) + post-exposure prophylaxis (azithromycin within 21 d of cough onset) + maternal Tdap (27-36 wk every pregnancy regardless of prior status) + DTaP routine pediatric series + Tdap adolescent + adult every 10 yr + cocooning (Cherry Pediatrics 2005 PMID 15876920; CDC pertussis; AAP Red Book 2024; Liang MMWR 2018 PMID 29702631)

No severity triggers fired against current inputs.

Plan

Regimen axis: **Pertussis azithromycin treatment (first-line all ages incl. < 1 mo) + erythromycin alternative > 1 mo + TMP/SMX alternative > 2 mo + PEP azithromycin for close contacts within 21 d + empiric bacterial co-empirics for superinfection + supportive care + maternal Tdap at 27-36 wk every pregnancy + DTaP routine pediatric series + Tdap adolescent + adult every 10 yr + cocooning** — step "Azithromycin first-line for pertussis treatment all ages including < 1 mo (per AAP — preferred over erythromycin due to pyloric stenosis risk)".
1. azithromycin Infant < 6 mo: 10 mg/kg PO daily × 5 d; Infant 6 mo+ / child / adolescent: 10 mg/kg day 1 (max 500 mg) then 5 mg/kg × 4 d (max 250 mg); Adult: 500 mg day 1 then 250 mg PO daily × 4 d PO daily × 5 d (macrolide, first line) — First-line per CDC pertussis + AAP Red Book 2024 + Tiwari MMWR 2005 PMID 16340941; short 5-d course; better tolerated than 14-d erythromycin per Altunaiji Cochrane 2007 PMID 17636756; preferred in < 1 mo per AAP — hypertrophic pyloric stenosis ~ 2-3× background risk (lower than erythromycin ~ 7×); monitor for vomiting in neonates post-azithromycin

Setting playbook (outpatient) — Manage uncomplicated immunocompetent pertussis in older child / adolescent / adult on azithromycin + droplet isolation at home until 5 d of effective antibiotic; PEP for susceptible close contacts within 21 d (azithromycin same dose as treatment); vaccination reconciliation (DTaP routine pediatric 5-dose; Tdap adolescent at 11-12 yr; adult Tdap once + Td or Tdap every 10 yr; maternal Tdap at 27-36 wk every pregnancy regardless of prior status; cocooning Tdap for close contacts of newborns); "100-day cough" persistence counseling (CDC pertussis; AAP Red Book 2024; Liang MMWR 2018)
2. azithromycin (first-line all ages) Infant < 6 mo: 10 mg/kg PO daily × 5 d; Infant 6 mo+ / child / adolescent: 10 mg/kg day 1 (max 500 mg) then 5 mg/kg × 4 d; Adult: 500 mg day 1 then 250 mg × 4 d PO daily × 5 d — Confirmed/suspected pertussis within 21 d of cough onset (First-line per CDC pertussis + AAP Red Book 2024)
3. erythromycin (alternative > 1 mo) Pediatric > 1 mo: 40-50 mg/kg/d PO divided q6h × 14 d; Adult: 500 mg PO q6h × 14 d PO q6h × 14 d — Age > 1 mo + azithromycin unavailable or contraindicated (Erythromycin alternative > 1 mo per CDC; CONTRAINDICATED < 1 mo per pyloric stenosis risk)
4. TMP/SMX (alternative > 2 mo if macrolide-intolerant) Pediatric > 2 mo: 8 mg/kg/d TMP component PO divided q12h × 14 d; Adult: TMP 160 mg / SMX 800 mg PO q12h × 14 d PO q12h × 14 d — Age > 2 mo + macrolide intolerance / contraindication; NOT in late pregnancy (TMP/SMX alternative > 2 mo per CDC; CONTRAINDICATED late pregnancy + < 2 mo per kernicterus / hyperbilirubinemia)
5. acetaminophen (fever / pain) Pediatric 10-15 mg/kg/dose q4-6h PRN (max 75 mg/kg/d); adult 500-1000 mg q6h PRN (max 4 g/d) PO q4-6h PRN — Fever or pain (Antipyretic + analgesic)
6. PEP azithromycin (close contact within 21 d) Same dose as treatment per age PO daily × 5 d — Close contact (household, school, healthcare, childcare) within 21 d of cough onset of index case (PEP same dose as treatment per Tiwari MMWR 2005 PMID 16340941 + CDC pertussis)
7. Tdap (maternal at 27-36 wk gestation) 0.5 mL IM IM single dose at 27-36 wk gestation — Pregnancy at 27-36 wk regardless of prior Tdap status (Most powerful upstream prevention of neonatal pertussis per Skoff CID 2017 PMID 29028938 + Skoff CID 2017 PMID 29028938; every pregnancy per ACIP regardless of prior Tdap)
8. DTaP (routine pediatric 5-dose) 0.5 mL IM × 5 doses IM 2, 4, 6, 15-18 mo + 4-6 yr — Routine pediatric immunization (Liang MMWR 2018 PMID 29702631 + ACIP)
9. Tdap (adolescent booster + adult every 10 yr + cocooning) 0.5 mL IM IM Adolescent 11-12 yr; adult Tdap once + Td or Tdap every 10 yr; cocooning single dose for close contact of newborn — Adolescent booster + adult catch-up + cocooning for close contacts of newborns (Liang MMWR 2018 PMID 29702631 + ACIP; cocooning synergistic with maternal Tdap per Skoff CID 2017 PMID 29028938)

Non-pharmacologic actions:
- Home droplet isolation until 5 d of effective antibiotic (or 21 d of cough if untreated)
- STAT public health notification (state/local public health department) on clinical suspicion — outbreak investigation + contact tracing
- Family + household exposure assessment + PEP azithromycin for all close contacts within 21 d of cough onset of index case
- School / workplace / childcare exclusion until 5 d of effective antibiotic
- Hydration counseling + return precautions for dehydration, new respiratory symptoms (especially apnea in infant siblings), new neuro features
- "100-day cough" persistence counseling — paroxysms may persist 2-3 mo in convalescent phase; inter-current viral URIs can trigger return of paroxysms
- Vaccination reconciliation at every visit until DTaP 5-dose series complete (pediatric) + adolescent Tdap at 11-12 yr complete + adult Tdap once + every 10 yr complete + maternal Tdap at 27-36 wk every pregnancy complete + cocooning Tdap for close contacts of newborns complete
- Outpatient peds-ID + ID + OB follow-up if applicable
- Public health reporting through outbreak resolution; cross-state coordination if travel-associated case

AVOID / contraindication checks:
- Erythromycin contraindicated under 1mo hypertrophic pyloric stenosis 7x background risk (Honein Lancet 1999 PMID 10609814; Eberly Pediatrics 2015 PMID 25687145; AAP Red Book 2024)
- Azithromycin elevated pyloric stenosis risk 2 to 3x background in neonates monitor vomiting (Eberly Pediatrics 2015 + subsequent cohorts; AAP Red Book 2024)
- Azithromycin qt prolongation caution with qt risk factors (FDA label)
- Azithromycin cardiovascular death warning FDA 2012 (FDA label)
- Erythromycin cyp3a4 interactions significant (FDA label)
- Tmp smx stevens johnson warning (FDA label)
- Tmp smx hyperkalemia aki warning elderly renal (FDA label)
- Tmp smx contraindicated late pregnancy kernicterus risk (FDA label)
- Tmp smx contraindicated under 2mo hyperbilirubinemia risk (FDA label)
- Tdap pregnancy category B safe at 27 36wk every pregnancy (ACOG; ACIP)
- Tdap injection site reactions common self limited (FDA label)
- Dtap febrile seizure 1 in 1500 doses generally benign counsel (CDC; FDA label)
- Droplet isolation until 5d effective antibiotic or 21d cough untreated (CDC)
- Immediate public health notification on clinical suspicion do not wait for labs (CDC; state notifiable disease law)
- Nasopharyngeal swab technique deep pertussis pcr not anterior nares (CDC)
- Wbc gt 100000 with pulmonary hypertension consider exchange transfusion leukapheresis institutional protocol (AAP Red Book 2024; case series)
- Bacterial superinfection empirics ceftriaxone plus vancomycin cross route pulm cap core v1 (IDSA/ATS CAP 2019)
- Antibiotic after 21d cough not recommended organism cleared cough post infectious (CDC pertussis)
- Cocooning tdap for all close contacts of newborns (ACIP; CDC)
- Maternal tdap at 27 36wk every pregnancy regardless of prior tdap status (ACIP; Skoff CID 2017)
- Vancomycin AUC target not trough (IDSA 2020 vancomycin consensus — AUC/MIC 400 600)

Monitoring

Regimen monitoring:
- STAT public health notification + droplet isolation + outbreak investigation (contact tracing for close contacts within 21 d of cough onset of index case) — TIME-CRITICAL, do NOT wait for lab confirmation
- Continuous cardiopulmonary monitoring in infants < 6 mo with pertussis — apnea may be the only feature; SpO2 + respiratory rate + apnea alarms
- Daily reassessment of respiratory + neuro + dehydration + cough-paroxysm frequency status
- PCR (nasopharyngeal swab) + IgG-PT serology confirmation (PCR preferred 1st 3 wk; serology in late phase ≥ 2 wk)
- CBC with differential — lymphocytosis trend; WBC > 100,000 with lymphocyte predominance → ICU + exchange transfusion / leukapheresis consideration
- Procalcitonin trend if antibiotics started — bacterial superinfection differential
- Serial creatinine + UOP during IV hydration and TMP/SMX (hyperkalemia / AKI monitoring per FDA label)
- ECG / QT monitoring if azithromycin in patient with QT-risk factors (cardiovascular history, drug interactions, electrolyte abnormalities per FDA label)
- Vomiting surveillance in neonates post-azithromycin (pyloric stenosis ~ 2-3× background risk per Eberly Pediatrics 2015)
- Vaccination tracking: pediatric DTaP 5-dose schedule audit (2/4/6/15-18 mo + 4-6 yr); adolescent Tdap at 11-12 yr; adult Tdap once + Td or Tdap every 10 yr; maternal Tdap at 27-36 wk every pregnancy; cocooning Tdap for close contacts of newborns
- Droplet isolation expiry: 5 d of effective antibiotic for home isolation outpatient (or 21 d of cough if untreated); hospital droplet isolation duration per institutional policy
- Family + caregiver education on return precautions + "100-day cough" persistence + close-contact PEP audit + cocooning Tdap plan
- School / workplace / childcare exclusion until 5 d of effective antibiotic; reporting to school health authorities if institutional cluster
- Public health follow-up through outbreak resolution; cross-state coordination if travel-associated case

Setting (outpatient) monitoring:
- Cough-paroxysm frequency trend (decreasing in convalescent phase; "100-day cough" can persist 2-3 mo)
- Fever resolution
- Hydration + nutrition + post-tussive emesis status
- Vaccination tracking: DTaP routine + adolescent Tdap + adult every 10 yr + maternal Tdap + cocooning Tdap audit
- Close-contact PEP audit (azithromycin within 21 d of cough onset of index case for all close contacts)

Follow-up plan: Post-pertussis: paroxysm-free convalescence; counsel on "100-day cough" persistence; return precautions for new respiratory features; vaccination reconciliation (DTaP routine pediatric audit; Tdap adolescent at 11-12 yr; adult every 10 yr; maternal at 27-36 wk every pregnancy; cocooning for close contacts of newborns). Post-pertussis pneumonia: respiratory recovery + lung function; ID follow-up if immunocompromised. Post-encephalopathy: neurology + neuropsychology + rehabilitation; serial imaging + functional assessment. Family education + contact tracing if institutional outbreak; public health reporting through resolution; close-contact PEP audit (azithromycin within 21 d of cough onset of index case).
- Close-out criterion: Follow-up + vaccination plan + family education + close-contact PEP audit delivered

Monitoring phase: Outpatient: paroxysm frequency + severity (decreasing trend in convalescent phase; may persist 2-3 mo "100-day cough"); fever resolution; return precautions for new respiratory / neuro / dehydration features; droplet isolation until 5 d of effective antibiotic. Inpatient / ICU: continuous cardiopulmonary monitoring for apnea in infants < 6 mo; daily reassessment of respiratory + neuro + dehydration status; serial WBC trend (WBC > 100,000 with pulmonary hypertension → ICU + exchange transfusion / leukapheresis consideration); serial creatinine for TMP/SMX hyperkalemia / AKI monitoring; procalcitonin trend if antibiotics started; ECG / QT monitoring if azithromycin in patient with QT-risk factors. Vaccination tracking: pediatric DTaP 5-dose schedule audit (2/4/6/15-18 mo + 4-6 yr); adolescent Tdap at 11-12 yr; adult Tdap once + Td or Tdap every 10 yr; maternal Tdap at 27-36 wk every pregnancy; cocooning for close contacts of newborns.

Disposition

Current setting: outpatient — Manage uncomplicated immunocompetent pertussis in older child / adolescent / adult on azithromycin + droplet isolation at home until 5 d of effective antibiotic; PEP for susceptible close contacts within 21 d (azithromycin same dose as treatment); vaccination reconciliation (DTaP routine pediatric 5-dose; Tdap adolescent at 11-12 yr; adult Tdap once + Td or Tdap every 10 yr; maternal Tdap at 27-36 wk every pregnancy regardless of prior status; cocooning Tdap for close contacts of newborns); "100-day cough" persistence counseling (CDC pertussis; AAP Red Book 2024; Liang MMWR 2018)

Disposition criteria:
- Sustained recovery — cough-paroxysm frequency decreasing + droplet isolation expired (5 d of effective antibiotic) + vaccination plan in progress + family education delivered + cocooning Tdap plan + close-contact PEP audit + outpatient follow-up scheduled with sub-specialty as indicated

Escalation triggers (move to higher acuity):
- New respiratory distress / SpO2 < 94% / apnea / cyanosis → urgent ED + CXR + IV antibiotics if bacterial superinfection features
- New neuro signs / seizures → urgent ED + MRI + LP
- Dehydration with inability to maintain oral intake → urgent ED + IV fluids
- Persistent fever > 48-72 h or new fever spike post-rash → suspect bacterial superinfection → re-evaluate
- WBC > 100,000 with lymphocyte predominance → urgent ED + ICU + exchange transfusion / leukapheresis consideration
- Infant sibling with apnea / cyanosis in household with index pertussis → urgent ED + cardiopulmonary monitoring

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [LIFE_THREATENING] Infant < 6 mo with confirmed/suspected pertussis (any phase: catarrhal, paroxysmal, convalescent) — life-threatening; admit (cardiopulmonary monitoring for apnea — apnea may be the only feature; whoop and post-tussive emesis often absent in infants); supportive (O2, NIV, ICU as needed); azithromycin first-line (10 mg/kg/d PO × 5 d; NEVER erythromycin < 1 mo per AAP — hypertrophic pyloric stenosis ~ 7× background risk per Honein Lancet 1999 PMID 10609814 + Eberly Pediatrics 2015 PMID 25687145); ID consult; STAT public health notification (CDC pertussis; AAP Red Book 2024)
- [LIFE_THREATENING] Apnea episodes in infant pertussis (may precede or replace classic paroxysms; whoop and post-tussive emesis often absent) — life-threatening; ICU + continuous cardiopulmonary monitoring + apnea alarms; supplemental O2 + NIV / mechanical ventilation if severe; mortality 1-2% in infants < 6 mo developed-world (up to 5-10% developing world); cross-route to peds.brue.v1 for BRUE / ALTE differential framework — pertussis must be ruled out before BRUE diagnosis (AAP Red Book 2024; CDC pertussis)
- [LIFE_THREATENING] Pertussis encephalopathy (~ 0.3-1%) or seizures (~ 2%) — life-threatening; admit ICU + supportive + neurology + EEG + MRI + LP + CSF studies (rule out bacterial meningitis + viral encephalitis); anoxic + hypoxic + direct-toxin etiologies; substantial mortality + permanent neurologic sequelae; continue azithromycin for pertussis; cross-route to id.bacterial-meningitis.core.v1 / .peds.v1 via workup.first_seizure for differential framework (AAP Red Book 2024; CDC pertussis)

Citations

- CDC Pertussis Treatment + Prevention Guidance (current 2024-2025) + AAP Red Book current edition (2024 + 2026 floor) Pertussis chapter + ACIP Pertussis / Tdap recommendations (maternal Tdap at 27-36 wk every pregnancy regardless of prior status) + Liang MMWR 2018 ACIP Tdap/DTaP comprehensive recommendation + Tiwari MMWR 2005 CDC pertussis treatment + PEP + Cherry Pediatrics 2005 adult / adolescent atypical pertussis review + Honein Lancet 1999 erythromycin neonatal pyloric stenosis + Eberly Pediatrics 2015 azithromycin neonatal pyloric stenosis + Skoff CID 2017 maternal Tdap timing 27-36 wk antibody transfer + Skoff CID 2017 maternal Tdap effectiveness 78-91% infant hospitalization reduction + Klein NEJM 2012 post-DTaP-era resurgence epidemiology + Klein NEJM 2012 DTaP waning immunity 5-10 yr + Altunaiji Cochrane 2007 antibiotics for pertussis meta-analysis + WHO Pertussis Guidelines 2024 + IDSA/ATS CAP 2019 bacterial superinfection + ACOG Practice Advisory Tdap in Pregnancy [PMID:29702631](https://pubmed.ncbi.nlm.nih.gov/29702631/)
- Cited evidence (PMID 16340941) [PMID:16340941](https://pubmed.ncbi.nlm.nih.gov/16340941/)
- Cited evidence (PMID 15876920) [PMID:15876920](https://pubmed.ncbi.nlm.nih.gov/15876920/)
- Cited evidence (PMID 10609814) [PMID:10609814](https://pubmed.ncbi.nlm.nih.gov/10609814/)
- Cited evidence (PMID 25687145) [PMID:25687145](https://pubmed.ncbi.nlm.nih.gov/25687145/)

Last reconciled with current guidelines: 2026-05-22.
References
  • CDC Pertussis Treatment + Prevention Guidance (current 2024-2025) + AAP Red Book current edition (2024 + 2026 floor) Pertussis chapter + ACIP Pertussis / Tdap recommendations (maternal Tdap at 27-36 wk every pregnancy regardless of prior status) + Liang MMWR 2018 ACIP Tdap/DTaP comprehensive recommendation + Tiwari MMWR 2005 CDC pertussis treatment + PEP + Cherry Pediatrics 2005 adult / adolescent atypical pertussis review + Honein Lancet 1999 erythromycin neonatal pyloric stenosis + Eberly Pediatrics 2015 azithromycin neonatal pyloric stenosis + Skoff CID 2017 maternal Tdap timing 27-36 wk antibody transfer + Skoff CID 2017 maternal Tdap effectiveness 78-91% infant hospitalization reduction + Klein NEJM 2012 post-DTaP-era resurgence epidemiology + Klein NEJM 2012 DTaP waning immunity 5-10 yr + Altunaiji Cochrane 2007 antibiotics for pertussis meta-analysis + WHO Pertussis Guidelines 2024 + IDSA/ATS CAP 2019 bacterial superinfection + ACOG Practice Advisory Tdap in Pregnancy — PMID:29702631
  • Cited evidence (PMID 16340941) — PMID:16340941
  • Cited evidence (PMID 15876920) — PMID:15876920
  • Cited evidence (PMID 10609814) — PMID:10609814
  • Cited evidence (PMID 25687145) — PMID:25687145