Ashry_Epidemiology of Measles

8/8/2019 Ashry_Epidemiology of Measles

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Epidemiology of MeaslesEpidemiology of Measles

Prof. Ashry Gad MohamedProf. Ashry Gad Mohamed

Prof. of EpidemiologyProf. of Epidemiology


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Highly contagious viral illnessHighly contagious viral illness

First described in 7th centuryFirst described in 7th century

Near universal infection of childhood inNear universal infection of childhood in

prevaccination eraprevaccination era

Common and often fatal in developingCommon and often fatal in developing

areasareas


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No second opportunity for measles immunization ( 45 )No second opportunity for measles immunization ( 45 )

94 % of all measles deaths in 200094 % of all measles deaths in 2000

Leading killer of childrenLeading killer of children

We know WH

ERE . . .We know WH

ERE . . .0

50,000

100,000

150,000

200,000

250,000

300,000

350,000

400,000

450,000

500,000

A

R SEAR E R WPR EUR A R


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Cases 2005Cases 2005

. An estimated 345 000 people, the majority. An estimated 345 000 people, the majority

of them children, died from measles in 2005.of them children, died from measles in 2005.

From 2000 to 2005, more than 360 millionFrom 2000 to 2005, more than 360 millionchildren globally received measles vaccine.children globally received measles vaccine.


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Global rogressGlobal rogressMeasles Mortality Reduction by 50% by 2005Measles Mortality Reduction by 50% by 2005

(compared to 999 : 875 000 deaths)(compared to 999 : 875 000 deaths)

0

00000200000

00000

00000

500000

600000

700000

800000

900000

999 2000 200 2002 200 200 2005

Estimated Measles Mortality by YearEstimated Measles Mortality by Year


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Deaths from MeaslesDeaths from Measles

Africa 2 000 [9 000Africa 2 000 [9 000 -- 4 000]4 000]

Americas < 000 [Americas < 000 [--]]

Eastern Mediterranean 9 000 [2 000Eastern Mediterranean 9 000 [2 000 -- 5 000]5 000] European < 000 [European < 000 [--]]

outhouth--East Asia 74 000 [ 2 000East Asia 74 000 [ 2 000 -- 2 000]2 000]

Western acific 5000 [ 000Western acific 5000 [ 000 -- 8000]8000]

TOTAL 45 000 [247 000TOTAL 45 000 [247 000 -- 458 000]458 000]


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Measles Mortality Reduction in EMRO Region

999-2004 EMRO

0

20 000

40 000

0 000

0 000

00 000

20 000

999 2000 200 2002 200 2004

ear

Esti

atedD

eat

s


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LibyaEgypt

Sudan

Morocco

Tunisia

Somalia

Saudi Arabia

Yemen

Oman

Djibouti

Pakistan

Afghanistan

IranIraq

Syria

Jordan

Lebanon

Palestine

QatarUAE Bahrain

Kuwait


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Percent reduction in estimated measlesPercent reduction in estimated measles

deaths by WHO region between 999 anddeaths by WHO region between 999 and

20022002

0

0

2

20

0

0

WPR EMR EUR lobal

Region

reduction


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Measles Case Counts andMeasles Case Counts and

Coverage audiA

rabia 98Coverage audiA

rabia 98 --20042004

010002000

3000400050006000700080009000

100001100012000

990

99

992

99

994

99

99

99

998

999

2000

200

2002

200

2004

ear

Cases

82

8486

88

90

92

9496

98

100

er

ent

overage


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There was a marked reduction in the epidemicThere was a marked reduction in the epidemic

peak from 500/100 000 in the 1970s to < 80/100peak from 500/100 000 in the 1970s to < 80/100000 in the 1990s.000 in the 1990s.

Incidence among children 6Incidence among children 68 months of age fell8 months of age fell

from > 400/100 000 before the implementation offrom > 400/100 000 before the implementation of

the new policy to < 100/ 100 000 in 1997.the new policy to < 100/ 100 000 in 1997.Similarly, among children aged 9Similarly, among children aged 911 months, the11 months, the

number of cases fell from > 200/100 000 beforenumber of cases fell from > 200/100 000 before

the implementation of the new policy to


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Measles PathogenesisMeasles Pathogenesis

Respiratory transmission of virusRespiratory transmission of virus

Replication in nasopharynx and regionalReplication in nasopharynx and regional

lymph nodeslymph nodes Primary viremia 2Primary viremia 2--3 days after exposure3 days after exposure

Secondary viremia 5Secondary viremia 5--7 days after exposure7 days after exposure

with spread to tissueswith spread to tissues


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Measles Clinical FeaturesMeasles Clinical Features

Incubation period 10Incubation period 10--12 days12 days

Stepwise increase in fever toStepwise increase in fever to103103F or higherF or higher

Cough, coryza, conjunctivitisCough, coryza, conjunctivitis , malaise,, malaise,

sneezing, rhinitis, congestionsneezing, rhinitis, congestion Koplik spotsKoplik spots

Prodrome


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Koplik's spots arepathognomonic in

measles appear on

the buccal andlower labial

mucosa opposite

the lower molars

as White spots

inside the mouth


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Measles Clinical FeaturesMeasles Clinical Features

22--4 days after prodrome, 14 days after4 days after prodrome, 14 days after

exposureexposure

Maculopapular, becomes confluentMaculopapular, becomes confluent Begins on face and headBegins on face and head

Persists 5Persists 5--6 days6 days

Fades in order of appearanceFades in order of appearance

Rash


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Child has a

rash causedby measles


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Measles

rash

coveringchild's

arms and

stomach


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ConditionCondition

DiarrheaDiarrhea

Otitis mediaOtitis mediaPneumoniaPneumonia

EncephalitisEncephalitis

HospitalizationHospitalization

DeathDeath

Percent reported

8

7

0.

8

0.2

Measles ComplicationsMeasles Complications

Based on 985- 992 surveillance data


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0

5

10

15

20

25

30


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Measles Laboratory iagnosisMeasles Laboratory iagnosis

Isolation of measles virus from a clinicalIsolation of measles virus from a clinical

specimen (e.g., nasopharynx, urine)specimen (e.g., nasopharynx, urine)

Significant rise in measles IgG by anySignificant rise in measles IgG by anystandard serologic assay (e.g., EIA, HA)standard serologic assay (e.g., EIA, HA)

Positive serologic test for measles IgMPositive serologic test for measles IgM

antibodyantibody


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Measles VirusMeasles Virus

Paramyxovirus (RNA)Paramyxovirus (RNA)

One antigenic typeOne antigenic type

Rapidly inactivated by heat and lightRapidly inactivated by heat and light


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ReservoirReservoir

HumanHuman

Incubation period.Incubation period.

Clinical caseClinical case

No animal reservoirNo animal reservoir


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TransmissionTransmission

The virus spreads by the respiratoryThe virus spreads by the respiratory

route via aerosol droplets androute via aerosol droplets and

respiratory secretions which can remainrespiratory secretions which can remaininfectious for several hours.infectious for several hours.

The infection is acquired through theThe infection is acquired through theupper respiratory tract or conjunctivaupper respiratory tract or conjunctiva


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In the preIn the pre--vaccination era the maximumvaccination era the maximum

incidence was seen in children aged 5incidence was seen in children aged 5 -- 99

years. By the age of 20 approximatelyyears. By the age of 20 approximately99% of subjects have been exposed to99% of subjects have been exposed to

the virus.the virus.

With the introduction of vaccine measlesWith the introduction of vaccine measles

infection has shifted to the teens ininfection has shifted to the teens incountries with an efficient programmecountries with an efficient programme..


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In contrast, in third world countries, measlesIn contrast, in third world countries, measles

infection has its greatest incidence ininfection has its greatest incidence in

children under 2 years of age.children under 2 years of age.

the disease is a serious problem with a highthe disease is a serious problem with a high

mortality (10%) with malnutrition being anmortality (10%) with malnutrition being an

important factorimportant factor in developing countriesin developing countries

In general measles mortality is highest inIn general measles mortality is highest in

children < 2 years and in adultschildren < 2 years and in adults


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Temporal patternTemporal pattern Peak in latePeak in late

winterwinterspringspring

CommunicabilityCommunicability 4 days before4 days beforeto 4 days after rash onset.to 4 days after rash onset.


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Strategy for sustainableStrategy for sustainable

measles mortality reductionmeasles mortality reduction

. Strong routine immunization. Strong routine immunization >> 90%90%

Reaching Every istrict StrategyReaching Every istrict Strategy

. Surveillance. Surveillance

2. Provide second opportunity for2. Provide second opportunity for

measles immunizationmeasles immunization One time onlyOne time onlycatchcatch--up campaign ( < 5 )up campaign ( < 5 )

FollowFollow--up campaigns every 3up campaigns every 3--4 years ( < 5 )4 years ( < 5 )

Routine scheduled second dose / opportunityRoutine scheduled second dose / opportunity

4. Improved case management4. Improved case management


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Palestine

Bahrain

Measles Campaigns in EMRO through 2005

Preschool and school age ( )

School age (5)

Preschool age ( )

Not done ( )

Ongoing (2)


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19 Live attenuated and killed vaccines

19 5 Live further attenuated vaccine

19 7 Killed vaccine withdrawn

19 8 Live further attenuated vaccine

(Edmonston-Enders strain)

1971 Licensure of combined measles-

mumps-rubella vaccine

1989 Two dose schedule

2005 Licensure of MMRV

Measles VaccinesMeasles Vaccines


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Measles VaccineMeasles Vaccine

CompositionComposition Live virusLive virus

EfficacyEfficacy 95% (range, 90%95% (range, 90%--98%)98%)

Duration ofDuration ofImmunityImmunity LifelongLifelong

ScheduleSchedule 2 doses2 doses Should be administered with mumps and rubella asShould be administered with mumps and rubella as

MMRMMR

The seroconversion rate is 95% and theThe seroconversion rate is 95% and the

immunity lasts for at least 10 years orimmunity lasts for at least 10 years ormore, possibly lifelongmore, possibly lifelong


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MMRV (ProQuad)MMRV (ProQuad)

Combination measles, mumps, rubellaCombination measles, mumps, rubella

and varicella vaccineand varicella vaccine

Approved children 12 months through 12Approved children 12 months through 12years of age (up to age 13 years)years of age (up to age 13 years)

Titer of varicella vaccine virus in MMRVTiter of varicella vaccine virus in MMRV

is more than 7 times higher thanis more than 7 times higher than

standard varicella vaccinestandard varicella vaccine


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MMR Vaccine FailureMMR Vaccine Failure

Measles, mumps, or rubella disease (or lack ofMeasles, mumps, or rubella disease (or lack of

immunity) in a previously vaccinated personimmunity) in a previously vaccinated person

2%2%--5% of recipients do not respond to the first5% of recipients do not respond to the firstdosedose

Caused by antibody, damaged vaccine, recordCaused by antibody, damaged vaccine, record

errorserrors

Most persons with vaccine failure will respondMost persons with vaccine failure will respond

to second doseto second dose


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Measles (MMR) Vaccine IndicationsMeasles (MMR) Vaccine Indications

All infantsAll infants >>12 months of age12 months of age

Susceptible adolescents and adultsSusceptible adolescents and adults

without documented evidence of immunitywithout documented evidence of immunity


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Measles Mumps Rubella VaccineMeasles Mumps Rubella Vaccine

12 months is the recommended and12 months is the recommended and

minimum ageminimum age

MMR given before 12 months should notMMR given before 12 months should notbe counted as a valid dosebe counted as a valid dose

Revaccinate atRevaccinate at >>12 months of age12 months of age


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Second Dose of Measles VaccineSecond Dose of Measles Vaccine

Intended to produce measles immunity inIntended to produce measles immunity in

persons who failed to respond to the firstpersons who failed to respond to the first

dose (primary vaccine failure)dose (primary vaccine failure) May boost antibody titers in some personsMay boost antibody titers in some persons


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Second Dose RecommendationSecond Dose Recommendation

First dose of MMR at 12First dose of MMR at 12--15 months15 months

Second dose of MMR at 4Second dose of MMR at 4--6 years6 years

Second dose may be given any timeSecond dose may be given any time >>44weeks after the first doseweeks after the first dose


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MMR Adverse ReactionsMMR Adverse Reactions

FeverFever 5%5%--15%15%

RashRash 5%5%

Joint symptomsJoint symptoms 25%25%

ThrombocytopeniaThrombocytopenia


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MMR Vaccine and AutismMMR Vaccine and Autism

Measles vaccine connection first suggestedMeasles vaccine connection first suggested

by British gastroenterologistby British gastroenterologist

Diagnosis of autism often made in secondDiagnosis of autism often made in secondyear of lifeyear of life

Multiple studies have shown no associationMultiple studies have shown no association


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MMR Vaccine and AutismMMR Vaccine and Autism

The evidence favors a rejection of a causalThe evidence favors a rejection of a causal

relationship at the population level betweenrelationship at the population level between

MMR vaccine and autism spectrumMMR vaccine and autism spectrum

disorders (ASD).disorders (ASD).

-- Institute of Medicine, April 2001Institute of Medicine, April 2001


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MMR VaccineMMR Vaccine

Contraindications and PrecautionsContraindications and Precautions

Severe allergic reaction to vaccineSevere allergic reaction to vaccine

component or following prior dosecomponent or following prior dose

PregnancyPregnancy ImmunosuppressionImmunosuppression

Moderate or severe acute illnessModerate or severe acute illness

Recent blood productRecent blood product


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The use of liveThe use of live--attenuated vaccine for postattenuated vaccine for post--

exposure prophylaxis is contraindicated.exposure prophylaxis is contraindicated.


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Ashry_Epidemiology of Measles