Download Epidemiology And Control Of Whooping Cough

DR. REEMA KUMARI
Associate professor
Department of community medicine and
public health
The earliest clear account of whooping
cough was described in 1640 by Baillow, an
epidemiologist
The name ‘pertussis’ means “violent cough”,
and was first used to describe the disease in
1679.
In China, the disease is known as “Hundred
Day Cough”
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An acute infectious disease, usually of young
children caused by B.pertussis.
Insidious onset with mild fever and an
irritating cough gradually becoming
paroxyamal with the characteristic “whoop”
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Pertussis toxin and
filamentous
hemagglutinin
(FHA) allow binding
of pertussis to
repsiratory
epithelial cells.
PT can then enter
the bloodstream.
Pertussis is a disease of worldwide
importance, with an estimated 285,000
deaths in 2001, with most occurring in Africa
and SE Asia
According to the WHO,2010 there are 1.29
lac cases reported globally, with 95%
occurring in developing countries,and the
DPT(3) Immunisation rate was 85%.
In India yr.1987 incidence was 1.63 lac
cases,in 2011only 39,091 cases were
reported (decline of 76%)
AGENT FACTORS
 B pertussis is very contagious, and attack
rates among susceptible groups range from
50-100% depending on the nature of the
exposure.
 B.pertusis occurs in smooth and rough
phases, capsulated and non-capsulated
form,elaborates an exotoxins and endotoxins
 B.pertusis is antigenically highly complex.it
carries 3 major agglutinogens-1,2,3 and
several minor ones
 Survives only for very short periods outside
the human body
AGE: disease of infants and pre-school
children; however, children under the age of
5 years are at the highest risk of developing
more serious symptoms.
Being in close contact with an infected person
for extended periods of time increases the
risk of becoming infected
IMMUNITY: recovery from whooping cough or
adequate immunisation is followed by
immunity.infants are susceptible to infection
from birth bec. Maternal antibody does not
appear to give them protection. no cross
immunity with B. Parapertussis
B. pertusis infects only man, source is a case
of pertusis
Transmission is felt to occur by aerosol
droplet, and exposure to a coughing patient.
There are no known animal reservoirs for B
pertussis, and the organism does not survive
for prolonged periods in the environment.
No long-term carrier state had been
identified, but asymptomatic culture positive
persons can be detected during known
exposures.
The bacilli occurs abundantly in the
nasopharyngeal and bronchial secretions,
which are infective
Objects freshly contaminated by such
discharges are also infective
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Whooping cough is most infectious during
catarrhal stage.
The infective period may be considered to
extend from a week after exposure to about 3
weeks after the onset of paroxysmal stage
Whole cell pertussis vaccine has been
responsible for a major reduction in disease
incidence, but has caused a shift in the peak
age of disease.
Stage 1 (Catarrhal):
• Cold, runny nose and irritating cough
Most infectious stage
Stage 2 (Paroxysmal):
• Severe series of coughs usually ending with a
high-pitched whoop
• The whoop starts 1 to 2 weeks after the cold
symptoms and lasts 1 to 2 months
• Thick, clear, sticky mucous may be coughed up
at the end of the coughing spasm
• Coughing spasms are more frequent at night
Stage 3 (Convalescent):
• Gradual disappearance of symptoms
occurring over 2 to 4 weeks, however,
coughing spells can last for weeks or months
• Cough may become louder and may sound
like it is getting worse as the person is
getting better
• Coughing may flare up again later in a cold
or upper respiratory illness. This does not
mean that the person has been re-infected
with pertussis
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•
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After an incubation period of 1-3 weeks,
signs and symptoms of the catarrhal phase
begin
Symptoms include rhinorrhea, lacrimation,
conjunctival injection, malaise, low grade
fever, and are indistinguishable from those of
many other URI’s.
After a few days and up to a week of these
symptoms, a dry nonproductive cough
develops, and this evolves into a
characteristic paroxysmal phase.
•
•
•
Patients are most contagious during the
catarrhal phase and during the first two
weeks after the onset of coughing.
Prodromal symptoms during this phase can
include complaints of pharyngeal discomfort.
During this phase, patients can develop a
marked leukocytosis, with WBC counts
greater than 50,000, with a relative
lymphocytosis (less common in adults).
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The cough paroxysm consists of a short
series of expiratory bursts, followed by an
inspiratory gasp, which results in the typical
“whoop”.
The paroxysmal phase usually lasts 1-6
weeks, but can last up to 10 weeks
Not all children with pertussis exhibit the
characteristic whoop, and it is fairly
uncommon in infants, who may have apneic
episodes
Child having Loud crowing inspiration
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In adults, whooping is variable, ranging from
20-40% in various studies. The disease is
generally milder, but the paroxysmal cough
may be just as prolonged.
Paroxysms can number more than 30 per 24
hours, and are more frequent at night, and
can be stimulated by external stimuli, such as
noises or cold air.
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•
•
Classically they may end with a vomiting
episode. They can be associated with
sweating, flushing and syncope. Patients may
cough up thick yellow plugs.
Pertussis is generally more severe in infants,
but presentation can be more atypical in
infants, as well as partially immunized
children and previously immunized
adolescents and adults.
In these groups the catarrhal phase can be
shortened, and the true whooping phase may
be absent.
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The convalescent phase begins with a
decrease in the intensity of the cough and
paroxysms, but can still last for weeks.
It is not clear if pertussis can cause long term
impairment of pulmonary function.
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Complications occurs in 5-6 percent of cases
The chief complications of pertussis are
bronchitis, bronchopneumonia and
bronchiactasis
secondary infections- otitis media or
pneumonia (either secondary to pertussis or
other organisms)
Aspiration can occur secondary to the
whooping and associated gasping
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Patients can develop subconjunctival
hemorrhages, epistaxis,haemoptysis and
punctate cerebral haemorrhages which may
cause convulsions and coma
CNS abnormalities can occur particularly in
children 6 months and younger.
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Direct fluorescent antibody tests (DFA) are
often used as well, but they can be less
sensitive and less specific, and may lead to
overdiagnosis and overtreatment (higher false
positives from cross reaction with normal
naso-pharyngeal flora).
With new PCR technology becoming available,
the ability to diagnose Bordetella infection
has been greatly enhanced
A clinical case is defined as a cough illness
lasting at least 2 weeks without other
apparent cause accompanied by one of the
following
 Paroxysms of coughing
 Inspiratory ‘whoop’
 Posttussive vomiting
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The newer macrolides (azithromycin and
clarithromycin) have good in vitro acitivty
against B pertussis, and Clarithromycin (500
mg bid) used for 10 – 14 days and
Azithromycin (500 mg/d) used for 5 – 7 days
have been used with good results.
Steroids may reduce the number and severity
of cough paroxysms, but are generally only
recommended for infants with serious
disease.
Antibiotics can be used for 2 purposes in the
control and prevention of pertussis:
1) Treatment to modify clinical symptoms of
pertussis by administering to symptomatic
patients
2) Prevention of secondary spread of
pertussis by administering to:
 a) Symptomatic patients (treatment) and
interrupting infectiousness and transmission
by eliminating the organism from the
respiratory system.
 b) Asymptomatic contacts (prophylaxis) and
interrupting transmission by eliminating any
organisms that may have been contracted
Other methods of preventing the spread of
Pertussis include:
• Washing hands with soap and warm water.
• Teaching children to cover mouth and nose if
coughing or sneezing and to wash hands after
doing so.
• Not sharing eating utensils and drinking
glasses.
• Minimizing the amount of contact you have with
someone you know is infected or if you are
infected, minimizing the amount of time you are
around others.
THANK YOU