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Pertussis (whooping cough)
Abd El-Salam Dawood MD
Interventional Pediatric Cardiologist
FIBMS-Ped FIBMS-PedCard
Essentials of diagnosis & typical features:
Prodromal catarrhal stage (1–3 weeks)
characterized by mild cough, coryza, and fever.
Persistent staccato, paroxysmal cough ending
with a high-pitched inspiratory “whoop.”
Leukocytosis with absolute lymphocytosis.
Diagnosis confirmed by fluorescent stain or
culture of nasopharyngeal secretions.
General consideration:
Pertussis is an acute respiratory tract infection that was
well described initially in the 1500s. Sydenham first
used the term pertussis, meaning "intense cough", in
1670; it is preferable to whooping cough because most
infected individuals do not “whoop.”
Pertussis is an acute, highly communicable infection of
the respiratory tract caused by Bordetella pertussis
(gram
negative
fastidious
coccobacillus)
and
characterized by severe bronchitis. Transmission
occurs by close contact with cases via aerosolized
droplets. Children usually acquire the disease from
symptomatic family contacts. Adults who have mild
respiratory illness, not recognized as pertussis,
frequently are the source of infection. Asymptomatic
carriage of B. pertussis is not recognized. Infectivity is
greatest during the catarrhal and early paroxysmal
cough stage (for about 4 weeks after onset).
B. pertussis organisms attach to the ciliated respiratory
epithelium and multiply there; deeper invasion does
not occur. Disease is due to several bacterial toxins,
the most potent of which is "pertussis toxin", which is
responsible for lymphocytosis and many of the
symptoms of pertussis.
Bordetella parapertussis causes a similar but milder
syndrome.
Pertussis is extremely contagious, with attack rates as
high as 100% in susceptible individuals exposed to
aerosol droplets at close range.
Neither natural disease nor vaccination provides
complete or lifelong immunity against pertussis re-
infection or disease. Protection against typical disease
begins to wane 3-5 yr after vaccination.
Coughing adolescents and adults (usually not
recognized as having pertussis) are the major
reservoir for B. pertussis and are the usual sources of
infection for infants and children. The incubation period
is 7 to 10 days.
Symptoms and signs:
The onset of pertussis is insidious, with catarrhal upper
respiratory tract symptoms (rhinitis, sneezing, and an
irritating cough). Slight
fever may be present;
temperature greater than 38.3°C suggests bacterial
superinfection or another cause of respiratory tract
infection. After about 2 weeks, cough becomes
paroxysmal, characterized by 10–30 forceful coughs
ending with a loud inspiration (the whoop). Infants and
adults with otherwise typical severe pertussis often
lack characteristic whooping. Vomiting commonly
follows
a
paroxysm
(post-tussive
vomiting).
Coughing is accompanied by cyanosis, sweating,
prostration, and exhaustion. This stage lasts for 2–4
weeks, with gradual improvement. Cough suggestive
of chronic bronchitis lasts for another 2–3 weeks.
Paroxysmal coughing may continue for some months
and may worsen with intercurrent viral respiratory
infection. In adults, older children, and partially
immunized individuals, symptoms may consist only of
irritating cough lasting 1–2 weeks. In the younger
unimmunized child, symptoms of pertussis last about
8 weeks or longer. Clinical pertussis is milder in
immunized children.
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Laboratory findings:
White blood cell counts of 20,000–30,000/µL with 70–
80% lymphocytes typically appear near the end of the
catarrhal stage.
Culture is considered the “gold standard” for laboratory
diagnosis of pertussis.
Identification of B pertussis by culture or polymerase
chain reaction (PCR) from nasopharyngeal swabs or
nasal wash specimens proves the diagnosis. After 4–
5 weeks of symptoms, cultures and fluorescent
antibody tests are almost always negative. Charcoal
agar containing an antimicrobial should be inoculated
as soon as possible; B pertussis does not tolerate
drying or prolonged transport. PCR detection is
replacing culture in some hospitals because of
improved sensitivity, decreased time to diagnosis and
cost.
Enzyme-linked immunosorbent assays (ELISA) for
detection of antibody to pertussis toxin or filamentous
hemagglutinin may be useful for diagnosis but are
currently not widely available, and interpretation of
antibody titers may be difficult in previously immunized
patients.
The chest x-ray reveals thickened bronchi and
sometimes shows a “shaggy” heart border, indicating
bronchopneumonia and patchy atelectasis.
Complications:
1. Bronchopneumonia: due to superinfection is
the most common serious complication. It is
characterized by abrupt clinical deterioration
during the paroxysmal stage, accompanied by
high fever and sometimes a striking leukemoid
reaction with a shift to predominantly
polymorphonuclear neutrophils.
2. Atelectasis: is a second common pulmonary
complication. Atelectasis may be patchy or
extensive and may shift rapidly to involve
different areas of lung.
3. Intercurrent viral respiratory infection: is
also a common complication and may provoke
worsening or recurrence of
paroxysmal
coughing.
4. Otitis media: is common.
5. Residual chronic bronchiectasis is infrequent
despite the severity of the illness.
6. Apnea and sudden death may occur during a
particularly severe paroxysm.
7. Seizures complicate 1.5% of cases and
encephalopathy
occurs
in
0.1%.
The
encephalopathy frequently is fatal. Anoxic brain
damage, cerebral hemorrhage, or pertussis
neurotoxins are hypothesized, but anoxia is
most likely the cause.
8. Epistaxis
and
subconjunctival
hemorrhages are common.
9. Increased intrathoracic and intraabdominal
pressure
may
lead
to
rib
fractures,
pneumothorax, incontinence, and hernias.
Differential diagnosis of sporadic "prolonged cough":
1. Bordetella
parapertussis
and
Bordetella
bronchiseptica.
2. Mycoplasma pneumonia
3. Chlamydia trachomatis and Chlamydophila
pneumonia
4. Respiratory
tract
viruses,
particularly
adenoviruses and respiratory syncytial viruses.
Prevention:
Pre-exposure prophylaxis: Active immunization with
DTP vaccine should be given in early infancy. Acellular
pertussis (DTaP) vaccines cause less fever and fewer
local and febrile systemic reactions and have replaced
the former whole cell vaccines.
Post-exposure prophylaxis:
Care of Exposed People: Household and Other
Close
Contacts
who
are
unimmunized
or
underimmunized should have pertussis immunization
initiated or continued using age-appropriate products
according to the recommended schedule as soon as
possible ( tetanus toxoid, reduced-content diphtheria,
and acellular pertussis vaccine (Tdap) in children 7
through 10 years and classic DTaP series for others).
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Chemoprophylaxis should be given to exposed family,
close and hospital contacts whatever their age or
vaccination status. The agents, doses, and duration of
prophylaxis are the same as for treatment of pertussis
Hospitalized children with pertussis should be isolated
because of the great risk of transmission to patients
and staff. In addition to standard precautions, droplet
precautions are recommended for 5 days after
initiation of effective therapy, or if appropriate
antimicrobial therapy is not given, until 3 weeks after
onset of cough.
Child
Care:
Pertussis
immunization
and
chemoprophylaxis should be given as recommended
for household and other close contacts.
Students and staff members: with pertussis should
be excluded from school until they have completed 5
days of the recommended course of antimicrobial
therapy. People who do not receive appropriate
antimicrobial therapy should be excluded from school
for 21 days after onset of symptoms.
Treatment:
A. Specific measures:
Antibiotics may "ameliorate" early infections but have
no effect on clinical symptoms in the paroxysmal stage.
A macrolide group is the drug of choice because it
promptly terminates respiratory tract carriage of B
pertussis. Patients should be given erythromycin
estolate (40 mg/kg/24 h in four divided doses for 14
days). Clarithromycin for 7 days and azithromycin for 5
days were equal to erythromycin for 14 days in one
small study.
Until additional information is available, azithromycin
is the drug of choice for treatment or prophylaxis of
pertussis in infants, in whom the risk of developing
severe pertussis and life-threatening complications
outweighs the potential risk of infantile hypertrophic
pyloric stenosis (IHPS) with azithromycin.
Trimethoprim-sulfamethoxazole is an alternative for
patients older than 2 months of age who cannot
tolerate macrolides or who are infected with a
macrolide-resistant strain.
Penicillins
and
first-
and
second-generation
cephalosporins are not effective against B pertussis.
Corticosteroids reduce the severity of disease but
may mask signs of bacterial superinfection.
Albuterol (0.3–0.5 mg/kg/d in four doses) has reduced
the severity of illness, but tachycardia is common when
the drug is given orally, and aerosol administration
may precipitate paroxysms.
B. General measures:
Nutritional support during the paroxysmal phase is
important. Frequent small feedings, tube feeding, or
parenteral fluid supplementation may be needed.
Minimizing stimuli that trigger paroxysms is probably
the best way of controlling cough. In general, cough
suppressants are of little benefit.
C. Treatment of complications:
Respiratory insufficiency due to pneumonia or other
pulmonary complications should be treated with
oxygen and assisted ventilation if necessary.
Convulsions
are
treated
with
oxygen
and
anticonvulsants.
Bacterial pneumonia or otitis media requires
additional antibiotics.
Prognosis:
The prognosis for patients with pertussis has improved
in recent years because of excellent nursing care,
treatment of complications, attention to nutrition, and
modern intensive care. However, the disease is still
very serious in infants under age 1 year (esp <3 mo);
most deaths occur in this age group. Children with
encephalopathy have a poor prognosis. Case-fatality
rates are approximately 1% in infants younger than 2
months of age.