- Bordetella pertussis, a highly communicable gram-negative coccobacillus, causes pertussis (whooping cough).
- B. pertussis is an exclusively human pathogen that is transmitted via airborne droplets and highly contagious.
- The incubation period is typically approximately one week but may be three weeks or longer.
The clinical dx definition
- a cough illness lasting two weeks without clear cause and one of the following symptoms:
- paroxysms of coughing,
- inspiratory whoop, or
- posttussive emesis,
- apnea (infant <1yr)
- In the setting of an outbreak or known close contact to a confirmed case of pertussis, the presence of a cough lasting ≥2 weeks is sufficient for clinical diagnosis (even in the absence of other symptoms).
Confirmed dx definition
- Patient’s illness meets criteria for “clinical case” plus one of the following: positive PCR assay, epidemiologic linkage to a laboratory- confirmed (PCR assay or culture) case or
- Acute cough illness of any duration and positive Bordetella pertussis culture
Probable dx definition
Patient’s illness meets criteria for “clinical case” plus all of the following: negative PCR assay, negative B. pertussis culture, no epidemiologic linkage to a laboratory-confirmed (PCR assay or culture) case
Ix:
- Patients with suspected early pertussis should be tested with nasopharyngeal culture and PCR.
- For patients with more than four weeks of cough, only serology is useful but the lack of a widely available, standardized test limits its use
Tx:
- Antihistamines, steroids, beta agonists, and immunoglobulins are not routinely recommended for pertussis treatment.
- Azithromycin (Zithromax) and clarithromycin (Biaxin) are recommended therapies for eradicating B. pertussis that are as effective as erythromycin but with better adherence to therapy.
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Clarithromycin (Biaxin) |
15 mg per kg divided into two doses per day for seven days (maximum dosage: 1 g per day) |
B. pertussis eradication rate similar to that of a 14-day erythromycin regimen with fewer side effects and better adherence; not FDA approved for pertussis |
Prevention:
- Close household contacts of patients with pertussis should be treated with antibiotics to prevent disease.
- Adolescents should receive Tdap vaccination instead of a Td booster to reduce the incidence of pertussis.
- Adults should receive a one-time Tdap booster instead of a Td booster to reduce the incidence of pertussis.
Pertussis infection in individuals w/o immunity (no prev vaccine) is characterized by 3 phases:
The total duration of all three phases is typically about three months.
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Catarrhal |
1-2 week |
xs Lacrimation, low-grade fever, malaise, mild conjunctival inflammation/injection, rhinorrhea, late-phase nonproductive cough Dx test more accurate during this phase |
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Paroxysmal |
1-6 week |
Paroxysms (bursts of vigorous coughing during a single exhalation) followed by an inspiratory “whooping” sound, post-tussive cyanosis, and emesis – pt often feel well between cough paroxysms – triggered by respiratory irritants (steam, mist, laughing, stretching yawning, exercise) & worse at night |
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In infants younger than six months (especially those younger than four weeks): apnea, bradycardia, prolonged cough, poor feeding, no paroxysms |
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Convalescent |
2-12 week |
Paroxysms gradually improve but recur with respiratory infections usually last 1-2 weeks |
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In adolescents or adults with history of prior infection or vaccine-induced immunity, classic manifestations often do not occur. The only symptom may be prolonged cough.
References:
- http://www.aafp.org/afp/2006/0801/p420.html
- UpToDate Jan 2015
Preparing for the CCFP Exam 2015 
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