EPIDEMIOLOGY OF PERTUSSIS

1. EPIDEMIOLOGY
OF PERTUSSIS
DR. MAHESWARI JAIKUMAR.
maheswarijaikumar2103@gmail.com

2. PERTUSSIS
• It is also called as WHOOPING
COUGH.
• Is an acute infectious disease,
usually of young children caused
by Bordetella pertussis.

3. • It is clinically characterized by an
insidious onset with mild fever
and an irritating cough, gradually
becoming paroxysmal with
characteristic “whoop” (loud
crowing inspiration) often with
cyanosis and vomiting.

4. • The spectrum of the disease
varies from severe illness to
atypical and mild illness without
whoop.
• The Chinese call it a “Hundred
Day Cough”.

5. EPIDEMIOLOGICAL
DETERMINANTS

6. AGENT
• The causative
agent in large
proportion is
Bordetella
pertussis.
• In less than 5%
cases it is
B.parapertussis.

9. • Certain viruses such as
adenovirus, parainfluenza virus
are also implicated in the
whooping cough syndrome.
• Bordetella pertussis occurs in
smooth and rough phases,
capsulated and non capsulated
form.

10. • It elaborates an exo and
edotoxin.
• Clinical disease is associated
with encapsulated, phase I
strains.

11. SOURCE OF INFECTION
• B. pertussis infects only man.
• The source of infection is a case of
pertussis.
• A chronic carrier state does not
exist.

12. INFECTIVE MATERIAL
• The bacilli occurs abundantly in
the nasopharyngeal and
bronchial secretions, which are
infective.
• Objects freshly contaminated by
such discharges are also infective.

13. INFECTIVE PERIOD
• Whooping cough is most
infectious during the catarrhal
stage.

14. • The infective period may be
considered to extend from one
week after exposure to about 3
weeks after the onset of the
paroxysmal stage although
communicability diminishes.
rapidly after the catarrhal stage.

15. SECONDARY ATTACK
• Averages 90% in unimmunized
household contacts.

16. HOST FACTORS

17. • AGE : Whooping cough is
primarily a disease of infants and
preschool children.
• The highest incidence is found
below the age of 5 years.

18. • In adults pertussis is often
unrecognized because of it’s
atypical course.
• However the older age groups
represent an important source of
infection for susceptible infants.

19. GENDER
• Incidence and fatality are
observed to be more among
female than male children.

20. IMMUNITY
• Adequate immunization ensures
a good immunity to the disease.
• Also recovery from pertussis also
confers immunity.

21. ENVIRONMENTAL FACTORS
• Pertussis occurs throughout the
year, but the disease shows a
seasonal trend with more cases
occurring during winter and
spring months, due to
overcrowding.

22. • Socio economic conditions and
ways of life also play a role in the
epidemiology of the disease.
• Thus the exposure of risk is
greater in the lower social
classes living in overcrowded
conditions.

23. MODE OF TRANSMISSION
• Whooping cough is mainly spread
by droplet infections and direct
contact.
• Each time the patient coughs,
sneezes or talks the bacilli are
spread into the air.

24. • Most children contract infection
from their playmates who are in
the early stages of the disease.
• The role of fomites appears
small, unless they are freshly
contaminated.

25. INCUBATION PERIOD
• Usually 7 to 14 days, but not
more than 3 weeks.

26. CLINICAL COURSE
• B pertussis produces a local infection;
the organism is not invasive.
• It multiplies on the surface
epithelium of the respiratory tract
and causes inflammation and
necrosis of the mucosa leading to
secondary bacterial infection.

27. • Three stages can be seen in the
clinical course of the disease.
• 1.CATARRHAL STAGE.
• 2. PAROXYSMAL STAGE.
• 3. CONVALESCENT STAGE.

29. CATARRHAL STAGE
• Lasts for 10 days.
• It is characterized by its insidious
onset, lacrimation, sneezing and
coryza, anorexia, malaise and
general hacking night cough that
becomes diurnal.

31. PAROXYSMAL STAGE
• Lasts for 2-4 weeks.
• It is characterized by bursts of
rapid, consecutive coughs
followed by a deep, high pitched
inspiration (whoop).

32. • It is usually followed by
vomiting.
• In young infants it may cause
cyanosis and apnoea.

33. • In adults and adolescents,
uncharacteristic, persistent
cough may be the only
manifestation .

34. CONVALESCENT STAGE
• Lasts for 1-2 weeks.
• The illness generally lasts 6 – 8
weeks.

36. COMPLICATIONS
• Complications occur in 5-6 percent
cases, most frequently in infants
aged less than 6 months.
• The chief complications are;
bronchitis, bronchopneumonia and
bronchietasis.

37. • The violence of the paroxysms
may precipitate subconjunctival
haemorrhages, epistaxis,
haemoptysis and punctate
cerebral haemorrhages which
may cause convulsions and
coma.

38. • Bronchopneumonia occurs in
about 5.2 % cases.
• The incidence of pertussis
related encephalopathies is 0.9%
/100,000.

39. CONTROL OF
PERTUSSIS

40. CASES
• The general principles of control
includes early diagnosis,
isolation and treatment of cases,
and disinfection of discharges
from nose and throat.

41. • Early diagnosis is possible only
by bacteriological examination of
nose and throat secretions
(obtained from nasopharyngeal
secretions - swabs).
• Erythromycin is the drug of
choice.

42. • A dose of 30-50mg/kg of body
weight in 4 divided doses for 10
days has been recommended.
• Possible alternatives are
ampicillin, septran or
tetracycline.

43. • Antibiotics may prevent or
moderate clinical pertussis when
given during incubation period
or in early catarrhal stage.

44. • During paroxysmal phase of
disease, antimicrobial drugs will
not change the clinical course
but may eliminate the bacterium
from the nasopharynx and thus
reduce the transmission of the
disease.

45. CONTACTS
• Infants and young children should
be kept away from cases.
• Close contacts may be given
prophylactic antibiotics
(erythromycin or ampicillin) for 10
days to prevent the infecting
bacteria to become established.

46. • The best protection is to
administer a booster dose of
DPT/DT to his siblings.

47. ACTIVE IMMUNIZATION
• The vaccine is usually
administered in the national
immunization programme as
combined DPT.

49. • In India, the National Policy is to
immunize against diptheria,
pertussis and tetanus
simultaneously, by administering
3 doses (each dose about 0.5 ml)
of DPT vaccine intramuscularly-
at 1 month interval, starting at
the age of 6 weeks.

50. • A booster dose is given at 18-24
months.
• Children whose vaccination
series has been interrupted
should have their series
resumed, without repeating
previous doses.

52. UNTOWARD REACTIONS
• Pertussis vaccines may give rise
to local reactions at the site of
injection, mild fever, irritability.

53. • The rare vaccine reactions are
persistent (more than 3 hours)
include inconsolable screaming,
seizures, hypotonic hypo
responsive episodes,
anaphylactic reaction and very
rarely encephalopathy.

54. CONTRAINDICATIONS
• Pertussis vaccine is
contraindicated in anaphylactic
reaction, encephalopathy, a
personal or strong family history
of epilepsy, convulsions or
similar CNS disorders or reaction
to one of the previously given
triple antigen injection.

55. PASSIVE IMMUNIZATION
• Hyperimmune globulin is
administered.
• The merit of passive
immunization is yet to be
established.

56. THANK YOU