Pertussis
Pertussis should be suspected in a child who has severe
paroxysmal coughing with posttussive emesis that occurs after mild symptoms of
an upper respiratory tract infection. Pertussis occurs in
three phases. The first phase is
a catarrhal stage that is characterized by mild
upper respiratory tract infection symptoms of nasal congestion, rhinorrhea,
conjunctival injection, and low-grade fever. The second phase is the
paroxysmal stage, which occurs between 2 and 4
weeks of illness and is characterized by increasingly frequent and severe
coughing paroxysms with posttussive emesis.
Subconjunctival hemorrhage may occur due to the severity of the coughing
spells. The classic whoop sound, which may or may not be
present, occurs from the deep inspiratory effort after a coughing paroxysm.
The third phase is the convalescent stage, which
usually lasts 1 to 2 weeks and is associated with slowly improving cough.
However, in some patients the cough may persist for weeks
to months. The total duration of
classic pertussis
usually is 6 to 8 weeks, although symptoms may only last 3 weeks.
Complications of pertussis include
seizures,
pneumonia,
encephalopathy, and
rarely death.
Pertussis is caused by Bordetella pertussis, a fastidious,
gram-negative, pleomorphic bacillus. Humans are the only known hosts of B
pertussis. Transmission occurs via close contact with
respiratory tract secretions of infected patients. Almost
50% of the cases are reported in adolescents and adults, but
24% of cases in the United States occur in infants younger
than 6 months of age and 43% in children younger
than 5 years of age. Patients are
most contagious during the catarrhal stage before the onset of coughing
paroxysms.
Culture of B pertussis is the diagnostic test of choice and requires inoculation
of nasopharyngeal mucus onto special medium with incubation for 10 to 14 days. A
positive culture is diagnostic, but cultures may be negative late in the course
of disease. A direct
immunofluorescent
assay of nasopharyngeal secretions for
pertussis
is available, but it has variable sensitivity and low specificity,
suggesting the need for culture confirmation in all suspected cases. No single
serologic test is diagnostic of pertussis. (Addendum,
Pertussis
PCR
is now the diagnostic test of choice - JS)
Antibiotics provided in the catarrhal
stage limit disease duration, but have no effect on disease once the paroxysmal
stage has begun. However, antibiotics are recommended to limit the spread of
disease. The drug of choice for treatment of pertussis is
oral erythromycin 40 to 50 mg/kg per day
qid
for 14 days. Azithromycin and clarithromycin may be effective in shorter
courses of 5 to 7 days. Supportive management is necessary in some patients.
Pertussis immunization is recommended for routine prevention of the infection.
The acellular vaccine usually is administered in combination with
diphtheria and tetanus toxoid. Incompletei mmunization and failure to provide
repeated booster vaccination can lead to an increased risk of disease.
Complications of immunizations
include local and febrile reactions, allergic reactions, seizures, and other
rare problems.
An aspirated foreign body may cause a cough and is most common in children 9
months to 2 years of age. Usually there is a history of foreign body aspiration.
Asymmetric breath sounds may indicate a foreign body. Persistent paroxysmal
coughing is not typical, and a prodrome of nasal congestion and rhinorrhea
followed by paroxysmal coughing suggests an infectious etiology. Viral illnesses
typically are associated with cough, but not with severe paroxysms and deep
whooping. Gastroesophageal reflux may cause chronic cough in some individuals,
but intermittent spasms and nighttime cough are more typical than paroxysmal
coughing. Finally, allergic rhinitis can be associated with nasal
congestion, rhinorrhea, wheezing, and cough, but paroxysmal coughing is unusual.
References:
American Academy of Pediatrics. Pertussis. In: Pickering LK, ed. 2000
Red Book: Report of the Committee on Infectious Diseases. 25th ed. Elk
Grove Village, Ill: American Academy of Pediatrics; 2000:435-448
Long SS. Pertussis (Bordetella pertussis and B. parapertussis). In:
Behrman RE, Kliegman RM, Jenson HB, eds. Nelson Textbook of
Pediatrics. 16th ed. Philadelphia, Pa: WB Saunders Co; 2000:838-842
Smith PK, Cowie H. Understanding Children's Development. 2nd ed.
Cambridge, Mass: Blackwell Publishers; 1991