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Pertussis
No longer just a children's disease
BY Ibrahim MomenKhan, MD and Natasha
Press, MD
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Ms. C., a 26-year-old teacher, presents
to her doctor with a 3-week history of dry cough. Her bursts of coughing
occur mainly at night and are disturbing her sleep. After one episode,
she vomited. She doesn't smoke and has a history of childhood asthma.
Ms. C. has tried antihistamines, cough syrup and salbutamol, but her
symptoms haven't improved. The patient is otherwise healthy, and has
never had a cough like this before.
Presentation
Physical examination
- vital signs normal
- head and neck: subconjunctival hemorrhage
- oropharynx unremarkable
- no palpable cervical lymphadenopathy
- no respiratory distress, crackles
or wheezing
- cardiac and abdominal exam normal
Differential diagnosis
- bacterial infection (Mycoplasma
pneumoniae, Chlamydia pneumoniae, Bordetella pertussis,
Mycobacterium tuberculosis)
- viral upper respiratory tract infection
with reactive airways disease
- asthma
- post-nasal drip
- gastroesophageal reflux
Investigations
- complete blood count and differential:
normal
- chest x-ray: peribronchial cuffing
- nasopharyngeal aspirate: negative
Diagnosis
and treatment
Ms. C. has pertussis. Her symptoms are mild, as they often
are in adults. The subconjunctival hemorrhage is secondary
to paroxysms of coughing. The nasopharyngeal aspirate gives
a false-negative result because of the prolonged time that's
passed since the onset of symptoms. She receives clarithromycin
for 7 days. Her paroxysms of coughing last for another week
and then gradually improve. Ms. C. lives with her 6-month-old
daughter, who's put on antibiotic prophylaxis.
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Making the case
Pertussis (whooping cough) is a highly communicable infection of
the respiratory tract caused by Bordetella pertussis. Although
it's most severe in infants, it can affect people at any age, and
the number of cases in adolescents and adults has been steadily
rising -- in Canada, adolescents and adults accounted for < 10%
of pertussis cases in 1995, but this number has gone up to >
30% in 2004. Part of this increase may be due to waning immunity,
especially in people who received their childhood pertussis vaccination
with the whole-cell formulation, which had a low efficacy.1
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