Pertussis / Whooping cough
A bacterial disease caused by the gram negative organism
Bordetella pertussis (1,2)
Bordetella parapertussis can also be responsible in some cases
and is not preventable with presently available vaccines (1,2).
It is an upper respiratory tract infection
with a characteristic, paroxysmal - whooping – cough.
The organism is found in the back of the throat of an infected person (3).
Transmission of the disease is from human to human by droplets (1).
It is a highly contagious disease with close direct contact with an infected person
resulting in transmission of the disease (1).
Up to 90% of household contacts develops the disease (2).
Traditionally, droplet transmission has been accepted
as occurring within 3 feet of the infected patient
but
recent studies have suggested that droplets can be dispersed
to a distance of 6 feet (1.9 metres) during coughing.
The Chinese refer to whooping cough as the 100 day cough;
this description gives the parents some idea of what to expect.
A positive history of pertussis vaccination
does not preclude the diagnosis
- the vaccination only confers 95% protection.
Also, maternal antibody
does not appear to confer any significant protection from infection.
In England and Wales, pertussis is a notifiable disease
(diagnosis made on clinical ground and laboratory confirmation is not required) (2,3).
References:
(1) Heininger U. Pertussis: what the pediatric infectious disease specialist should know. Pediatr Infect Dis J. 2012;31(1):78-9.
(2) Public Health England (PHE) 2018. Guidelines for the Public Health Management of Pertussis in England
(3) Public Health England (PHE). Pertussis brief for healthcare professionals
Clinical features
Incubation period is on average between 7–10 days (range 5–21 days)
Infectious period is for 21 days after the onset of symptoms (1).
Classic (severe) pertussis,
as defined by the World Health Organization (WHO),
consists of at least 21 days of cough illness with paroxysms,
associated whoops or post-tussis vomiting, and culture confirmation (1).
Clinical course of pertussis can be divided into 3 phases (2):
Catarrhal phase.
Lasts for 7-10 daysPertussis has an insidious onset with symptoms similar to mild respiratory infection
(coryza, low grade fever,
mild, occasional cough which gradually becomes more pronounced
and comes in bursts or short paroxyms).
and progresses to the paroxysmal coughing stage.
Paroxysmal phase.
During a paroxysm, each inspiration is followed by
a rapid succession of expiratory hacking coughs.
Paroxysms of cough:
often lasts for two to three months
("one-hundred-day cough") (1)
occur frequently at night,
with an average of 15 attacks per 24 hours
increase in frequency during the first 1- 2 weeks,
remain at the same frequency for 2-3 weeks,
and then gradually decrease (2)
Spasms of coughing may be followed by an inspiratory whoop,
particularly in older children,
and the child may become cyanosed or apnoeic.
The child may vomit thick mucus or food after a paroxysm,
and after a spasm the child may be exhausted.
Convalescent phase.
There is gradual recovery.
Lasts for 2-6 weeks (but can persist for months) (1,2).
Between coughing spasms, the child is usually perfectly well
which may obscure the diagnosis unless careful attention is paid to the history.
There are no added chest sounds.
The paroxysms of coughing may result in rise in intrathoracic pressure and reduction in venous return to the heart. The increased capillary pressure may then result in capillary rupture, particularly around the eyes causing petechiae and sometimes bruises.
Paroxysms often recur with subsequent respiratory infections for many months after the onset of pertussis (2).
References:
(1) Public Health England (PHE). Pertussis brief for healthcare professionals
(2) Centers for Disease Control and Prevention (CDC) 2013. Pertussis (Whooping Cough)
