Transcript EPIDEMIOLOGY AND CONTROL OF WHOOPING COUGH

DR. REEMA KUMARI
Associate professor
Department of community medicine and public health
K.G. Medical University, Lucknow
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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 respiratory
epithelial cells.
PT can then enter the
bloodstream.
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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 lacs cases
reported globally, with 95% occurring in developing
countries, and the DPT(3) Immunization rate was
85%.
In India yr.1987 incidence was 1.63 lacs cases, in
2011only 39,091 cases were reported (decline of
76%)
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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
Bordetella pertusis
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 immunization 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
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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.
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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
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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 highpitched 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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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.
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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 acitivity 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.
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Steroids may reduce the number and severity of
cough paroxysms, but are generally only
recommended for infants with serious disease.
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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
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Prevention of secondary spread of pertussis by
administering to:
Symptomatic patients (treatment) and interrupting
infectiousness and transmission by eliminating the
organism from the respiratory system.
Asymptomatic contacts (prophylaxis) and
interrupting transmission by eliminating any
organisms that may have been contracted
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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.
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