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PERTUSSIS
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PathogenesisClinical pictureLab treatment amp Prophylaxis By Syed Nafeez Pathogenesis BPertussis is an obligate human parasite surviving only for ID: 613908 Download Presentation

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Slide1

PERTUSSIS

Pathogenesis,Clinical picture,Lab ∆,treatment & Prophylaxis

By

Syed

NafeezSlide2

Pathogenesis:

B.Pertussis is an obligate human parasite, surviving only for brief

periods

outside

the host.

Source

:

Early

cases,particularly in catarrhal stage

Carriers

Fomites

Mode of transmission:

Inhalation of

infected

aerosols

(

droplet

infection)

Habit:

localized

in

cilia

of

resp.epitelium,doesn’t

invade

the

bloodstreamSlide3

Infected cilia by

B.pertussis bacilli

bacillus

ciliaSlide4

Mechanism:

Droplet nuclei containing B.pertussis are inhaledAdherence &

rapid

multiplication on

cilia

of

resp.epithelium

of

nasopharynx,trachea

&

bronchiLiberation of

toxins

(PT,TCT)&

other substances…(FHA,AC)Paralyse cilia causing insitu Θ of natural defences of resp.tract secondary infections Irritate cells excessive secretions cough & catarrhal sympt Necrosis with polymorphonuclear obstruction of bronchioles ATELECTASIS infiltration diminished oxygenationInterstitial pneumonia,bronchopneumonia contributes to↑frequency of convulsions in infantsSlide5

Title

ContentSlide6

Host response:

Humoral response by the production of IgA & pertussis toxin antibodies is effective.

These

prevent

attachment

of the

bacillus

.Slide7

Clinical picture:

Pertussis has an insidious onset after an IP of 1-2 weeks & a protracted course comprising of 3 stages:

Catarrhal stage

Paroxysmal stage

Convalescent stage

Each

lasting for an

approximate

of 2

weeksSlide8

Catarrhal stage:

There’s -low grade fever,malaise -catarrhal symptoms-sneezing,

rhinorrhoea

&

lacrimation

-

dry,irritating

cough

During

this

stage the person is highly infectious as large number of bacilli are sprayed in the dropletsThe disease can be arrested at this stage by antibiotic treatment but ∆

is very difficult ‘coz

of its resemblance to typical VIRAL URI wit

flu like symptoms. Slide9

Paroxysmal stage:

Characterised by distinctive bouts of ↑frequency & intensity of cough that’s explosive in natureDuring

each

bout,the

patient

experiences

violent

spasms

of continuous

coughing that almost

empties

the

lungs following which there’s deep inspiration that produces the characteristic ‘WHOOP’The patient’s exhausted at the end of each bout.Post tussive vomiting,cyanosis & convulsions may occur.Young infants become apnoeic.Slide10
Slide11

About 40-80 bouts

occur throughout the day,more severe at night,yielding thick

mucous

plugs

.

‘WHOOP’ & major complications

occur

predominantly

in children

The paroxysmal

coughing

predominates in older children & adults.Slide12

T

Blood changes are distinctive & aid in ∆.There’s marked Leucocytosis with an absolute lymphocytosis

.

TLC

-16,000-30,000/

μ

L with 60-80% being lymphocytes

lymphocytes in this blood smear from an 18-month-old  child with

the

infection have

lobulated nuclei.The cytology of the cells could be mistaken  for neoplastic lymphocytes.

Lymphocytes with lobulated nucleiSlide13

Convalescent stage:

There’s ↓frequency & severity of cough.The disease lasts for 6-8 weeks,though it

maybe

very

protracted

as in

premature

infants,the malnourished, immunocompromised,people with

genetic

susceptibility.Slide14

Complications:

Pulmonary-pneumonia -sc emphysema -atelectasis

Neurological

-epilepsy,paralysis

Miscellaneous

-

haemorrhage

(

sub-conjunctival,epistaxis

) -

otitis

media

-dehydration,malnutritionIn adults-rib fractures,back pain,hearing loss,urinary incontinence,hernias,rectal prolapse.

Directly by B.pertussis

Secondary infections

aspirationalSlide15

Lab ∆:

Specimens: nasopharyngeal secretions blood(serum) for serological testing

These

are

processed

through

:

Culture

Direct Fluorescent Ab

testing

Serological

techniques-Ab

titres,ELISAPCRSlide16

Culture:

Nasopharyngeal secretions required for culture are collected by following 4 methods:1)

Cough

plate

method

:

A culture plate of Bordet Gengou

Glycerine

Potato

Blood Agar is held

10-15 cm

infront

of patient’s mouth during a bout of spontaneous or induced cough,such that the resp. exudate impinges directly on the medium.The plate’s sealed & incubated for 48-72 hrs.Advantage is that the

specimen is innoculated

directly,at bedside.

Slide17

2)Pernasal

swab:A swab (dacron or calcium alginate) mounted on a flexible nichrome wire, is passed

along

the

floor

of nasal

cavity

&

material

collected from the pharyngeal

wall

.

Yields the highest % of isolation.Slide18

3)Nasopharyngeal aspiration:

Collected through a soft catheter attached to a syringeIs the ‘preferred’

specimen

.

4)

Postnasal

/

peroral

swab

:

A

cotton

swab(West’s post nasal swab) is passed through mouth & secretions from posterior pharyngeal wall,collected.There’s possibility of salivary contamination.Slide19

Specimens

should be innoculated immediately on BGGPB Agar or its modifications like Lacey’s

DFP medium

In case of

delay,transport

media are

used

:

0.25-0.5 ml of

Casamino

acid

solution,pH

-7.2

Modified Stuart’s mediumMischulow’s charcoal agarModified Regan-Lowe medium:Is a ½ strength charcoal agar supplemented with 10% horse blood & cephalexin(40mg/L)It Θ growth of nasopharyngeal flora.Is also the

medium of choice for culture.Culture plates are incubated for 7 days at high humidity & temperature of 35-36̊ C .

Should be checked for any growth after 48-72 hrs of innoculation & periodically thereafter.Slide20

A positive culture shows the

characteristic ‘bisected pearls’ or ‘mercury drop’ colonies.

Confluent

growth

shows aluminium

paint

appearance

Microscopy

shows a non

motile,gram

negative bacillus.Slide21

Direct FA

testing:Used to identify the bacillus either in direct smears of clinical

specimens

or

from

culture.

Is

inexpensive

.

Provides rapid

diagnosis

&

yields positive results when cultures are negative due to use of antibiotics.Lacks specificity & sensitivity due to cross-reactions with nasopharyngeal flora…..hence,unreliable & no longer recommended.Slide22

Serological techniques:

Focus on identifying significant variations in IgG & IgA titres(upto 4 fold ↑) against

relavant

B.pertussis

virulence

factors

in

both

acute & convalescent phases of the

disease

.Hence,for accurate

∆,

serum

samples in both phases of disease are to be collected.Rise in Ab titres is demonstrated by:Agglutination not helpful as the rise in agglutinating &Gel precipitation precipitating Abs doesn’t occur untill 3rd week

Complement fixation tests of illness

ELISA- highly specific

Proposed as diagnostic method in culture sensitive casesA

significant ↑ in titres(8E -2fold) between acute & convalescent phase is diagnostic of the

diseaseSlide23

PCR:

Most sensitive method to ∆ PertussisSpecimen used – nasopharyngeal aspiration

Primers

for

both

B.pertussis

&

B.parapertussis

should be included

Gives

positive

results even when the organism can’t be cultured.THE BOTTOM LINE:A major problem is the lack of access to diagnostic laboratory methods. Many routine laboratories are not equipped for the diagnosis of B. pertussis infection.

This is the result of a general medical misconception that B. pertussis infection does not frequently occur in the populationSlide24

Treatment:

B.Pertussis isn’t susceptible to penicillinsErythromycin is DOC adults

-250-500mg/6th

hr

14

days

children

-30-60mg/kg/

day

Clarithromycin

Azithromycin

Cotrimoxazole

Chloremphenicol Cough sedatives are not usefulCorticosteroids reserved in severe cases, reduce duration of paroxysmal stage.Adrenergic ᵦ2 stimulants,reduce severity of paroxysms, more useful in infants. Slide25

Prophylaxis:

Preventing the spread of disease by isolation isn’t preferred as max.infectivity is in early stage

when

is

difficult

.

Hence,prophylactic

measures mainly include:

immunoprophylaxis

Vaccines

currently used:DPT/DTwP/Triple antigen vaccineDTaPTdapChemoprophylaxisGeneral prophylaxisSlide26

Immunoprophylaxis:

1)DPT/DTwP/Triple antigen vaccine:Composed of

diphteria

&

tetanus

toxoids,killed

B.pertussis

(

smooth phase-1 strain)adsorbed on aluminium phosphate.thiomersol

as

preservative

Dosing schedule:3 Primary doses-at 6,10 & 14 weeks of life2 Booster doses-1st booster at 15-18 months -2nd at 5 years Dose & route:0.5 ml,IMSite: AL aspect of thigh in infants

or deltoid Slide27

Side

-effects:Minor reactions:Localized

to

site-soreness,swelling,redness

Systemic-fever,fussiness,drowsiness,anorexia

Moderate

reactions

:

Seen

in about 1:100/1000

shots

:

Crying non-stop for 3 hrs or moreFever of 105̊ F or moreLess often in about 1:1750 shots:Seizures(convulsions,spasms,staring spells)Collapse or fainting-child becomes blue,pale,limp & non-responsive

Severe reactions:rareProlonged

seizures,↓consciousness,coma,permanent brain damage &

death.!!!DPT vaccine is

contraindicated if moderate to

severe reactions

occur.Also contraindicated

below 6 weeks of life & above

6 yrs

Last for 1-2 days

Treat with analgesicsSlide28

2)

DTaP Vaccine: Is an acellular vaccine with pertussis

component

consisiting

of

inactivated

pertussis

toxin, filamentous

hemagglutinin

,

pertactin

, or

fimbriae

along with diphteria & tetanus toxoids in concentrations similar to DTwP vaccine.Indicated for children of 6 weeks-6 years of life.Dosing schedule is the same.Slide29

3)Tdap

vaccine: Is an acellular vaccine with concentrations of diphteria toxoid & pertussis component

reduced

to

1/10

of

DTaP

vaccine.

for adolescents between the ages of 10 and 18 years

preservative free (which means that, like most new vaccines, it doesn't contain

thimerosal

)

A similar

Tdap vaccine, Adacel, is being reviewed by the FDA & might be available for people between the ages of 11 and 64, which would be good news for adults who also want protection against pertussis.Slide30

Prevention and treatment prophylaxis of secondary cases

The CDC has defined a close contact as:someone having face-to-face exposure within 3 feet of a symptomatic patient someone who has had direct contact with respiratory, oral, or nasal secretions from a symptomatic patient someone who has shared the same confined space for more than 1 hour with a symptomatic person.

Chemoprophylaxis is given with recommended antibiotics and dosage

regimens,identical

to those used for treatment of active infection.

should be started in the

asympto-matic

person within 21 days of cough onset in the index patient.

highly recommended for all children younger than 12 months and women in the third trimester of pregnancy who have been exposed to

pertussis

Slide31

Epidemiology:

Predominantly a pediatric disease.Incidence & mortality highest in

1st

year

of life.

Common in

females

than

males

at all ages.

Worldwide

distribution

with most deaths occuring in Africa, Asia,central & latin America.Occurs endemically & epidemicallyIn recent years,there’s been resurgence of the disease in USA & eastern european countriesAlso,there’s

an ↑ in number of cases being reported in

Asia. Slide32

The Statistics:

According to WHO estimates,around 2.95 lakh persons died of whooping cough in 2002.

In

developing

countries,the

case

fatality

rates range

from

4-15% in infantsAbout 10% of cases & 50% of

deaths

occur in children <1yrIn India, there’s been marked decline in reported cases from 1987-2005 year cases reported 1987 1.63 lakh 2002 26700 2005 43955Slide33

THANK YOUSlide34

XCUSE me

if u have slept through!!

&

Shom More....
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