Epidemiology of MeaslesEpidemiology of Measles
Prof. Ashry Gad MohamedProf. Ashry Gad Mohamed
Prof. of EpidemiologyProf. of Epidemiology
Highly contagious viral illnessHighly contagious viral illness First described in 7th centuryFirst described in 7th century Near universal infection of childhood in Near universal infection of childhood in
prevaccination eraprevaccination era Common and often fatal in developing Common and often fatal in developing
areasareas
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 WHERE . . .We know WHERE . . . 0
50,000100,000150,000200,000250,000300,000350,000400,000450,000500,000
AFR SEAR EMR WPR EUR AMR
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 million From 2000 to 2005, more than 360 million children globally received measles vaccine.children globally received measles vaccine.
Global ProgressGlobal ProgressMeasles Mortality Reduction by 50% by 2005 Measles Mortality Reduction by 50% by 2005
(compared to 1999 : 875,000 deaths)(compared to 1999 : 875,000 deaths)
0
100000
200000
300000
400000
500000
600000
700000
800000
900000
1999 2000 2001 2002 2003 2004 2005
Estimated Measles Mortality by YearEstimated Measles Mortality by Year
Deaths from MeaslesDeaths from Measles
Africa 126 000 [93 000 - 164 000] Africa 126 000 [93 000 - 164 000] Americas <1 000 [-] Americas <1 000 [-] Eastern Mediterranean 39 000 [26 000 - 53 000] Eastern Mediterranean 39 000 [26 000 - 53 000] European <1 000 [-] European <1 000 [-] South-East Asia 174 000 [126 000 - 233 000] South-East Asia 174 000 [126 000 - 233 000] Western Pacific 5000 [3000 - 8000] Western Pacific 5000 [3000 - 8000] TOTAL 345 000 [247 000 - 458 000]TOTAL 345 000 [247 000 - 458 000]
Measles Mortality Reduction in EMRO Region, 1999-2004 EMRO
0
20,000
40,000
60,000
80,000
100,000
120,000
1999 2000 2001 2002 2003 2004
Year
Esti
mate
d D
eath
s
LibyaEgypt
Sudan
Morocco
Tunisia
Somalia
Saudi Arabia
Yemen
Oman
Djibouti
Pakistan
AfghanistanIranIraq
Syria
Jordan
LebanonPalestine
QatarUAE Bahrain
Kuwait
Percent reduction in estimated measles Percent reduction in estimated measles deaths by WHO region between 1999 and deaths by WHO region between 1999 and
20022002
-40
-35
-30
-25
-20
-15
-10
-5
0
AFR SEAR WPR EMR EUR Global
Region
% r
edu
ctio
n
Measles Case Counts and Measles Case Counts and Coverage Saudi Arabia 1983-2004Coverage Saudi Arabia 1983-2004
0100020003000400050006000700080009000
100001100012000
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
Year
Cas
es
828486889092949698100
Per
cent
cov
erag
e
There was a marked reduction in the epidemic There was a marked reduction in the epidemic peak from 500/100 000 in the 1970s to < 80/100 peak from 500/100 000 in the 1970s to < 80/100 000 in the 1990s. 000 in the 1990s.
Incidence among children 6–8 months of age fell Incidence among children 6–8 months of age fell from > 400/100 000 before the implementation of from > 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 9–11 months, the Similarly, among children aged 9–11 months, the number of cases fell from > 200/100 000 before number of cases fell from > 200/100 000 before the implementation of the new policy to <100/100 the implementation of the new policy to <100/100 000 in 1997. 000 in 1997.
2005 373cases2005 373cases
Measles PathogenesisMeasles Pathogenesis
Respiratory transmission of virusRespiratory transmission of virus Replication in nasopharynx and regional Replication in nasopharynx and regional
lymph nodeslymph nodes Primary viremia 2-3 days after exposurePrimary viremia 2-3 days after exposure Secondary viremia 5-7 days after exposure Secondary viremia 5-7 days after exposure
with spread to tissueswith spread to tissues
Measles Clinical FeaturesMeasles Clinical Features
Incubation period 10-12 daysIncubation period 10-12 days
Stepwise increase in fever to Stepwise increase in fever to 103°F or higher103°F or higher
Cough, coryza, conjunctivitis Cough, coryza, conjunctivitis , malaise, , malaise, sneezing, rhinitis, congestionsneezing, rhinitis, congestion
Koplik spotsKoplik spots
Prodrome
Koplik's spots, are pathognomonic in measles, appear on the buccal and lower labial mucosa opposite the lower molars as White spots inside the mouth
Measles Clinical FeaturesMeasles Clinical Features
2-4 days after prodrome, 14 days after 2-4 days after prodrome, 14 days after exposureexposure
Maculopapular, becomes confluentMaculopapular, becomes confluent Begins on face and headBegins on face and head Persists 5-6 daysPersists 5-6 days Fades in order of appearanceFades in order of appearance
Rash
Child has a rash caused by measles
Measles rash covering child's arms and stomach
ConditionConditionDiarrheaDiarrheaOtitis mediaOtitis mediaPneumoniaPneumoniaEncephalitisEncephalitisHospitalizationHospitalizationDeathDeath
Percent reported876
0.1180.2
Measles ComplicationsMeasles Complications
Based on 1985-1992 surveillance data
0
5
10
15
20
25
30
<5 5-19 20+
Age group (yrs)
Perc
en
t
Pneumonia Hospitalization
Measles Complications by Age GroupMeasles Complications by Age Group
Measles Clinical Case DefinitionMeasles Clinical Case Definition
Generalized rash lasting >3 days, Generalized rash lasting >3 days, andand
Temperature 101°F (>38.3°C), andTemperature 101°F (>38.3°C), and Cough or coryza or conjunctivitisCough or coryza or conjunctivitis
Measles Laboratory DiagnosisMeasles Laboratory Diagnosis
Isolation of measles virus from a clinical Isolation of measles virus from a clinical specimen (e.g., nasopharynx, urine)specimen (e.g., nasopharynx, urine)
Significant rise in measles IgG by any Significant rise in measles IgG by any standard serologic assay (e.g., EIA, HA)standard serologic assay (e.g., EIA, HA)
Positive serologic test for measles IgM Positive serologic test for measles IgM antibodyantibody
Measles VirusMeasles Virus
Paramyxovirus (RNA)Paramyxovirus (RNA) One antigenic typeOne antigenic type Rapidly inactivated by heat and lightRapidly inactivated by heat and light
ReservoirReservoir
HumanHuman Incubation period. Incubation period.
Clinical caseClinical case
No animal reservoirNo animal reservoir
TransmissionTransmission The virus spreads by the respiratory The virus spreads by the respiratory
route via aerosol droplets and route via aerosol droplets and respiratory secretions which can remain respiratory secretions which can remain infectious for several hours.infectious for several hours.
The infection is acquired through the The infection is acquired through the upper respiratory tract or conjunctivaupper respiratory tract or conjunctiva
In the pre-vaccination era, the maximum In the pre-vaccination era, the maximum incidence was seen in children aged 5 - 9 incidence was seen in children aged 5 - 9 years. By the age of 20, approximately years. By the age of 20, approximately 99% of subjects have been exposed to 99% of subjects have been exposed to the virus. the virus.
With the introduction of vaccine, measles With the introduction of vaccine, measles infection has shifted to the teens in infection has shifted to the teens in countries with an efficient programmecountries with an efficient programme..
In contrast, in third world countries, measles In contrast, in third world countries, measles infection has its greatest incidence in infection 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 high the disease is a serious problem with a high mortality (10%) with malnutrition being an mortality (10%) with malnutrition being an important factorimportant factor in developing countries in developing countries
In general measles mortality is highest in In general measles mortality is highest in children < 2 years and in adultschildren < 2 years and in adults
Temporal patternTemporal pattern Peak in late Peak in late winter–springwinter–spring
CommunicabilityCommunicability 4 days before 4 days before to 4 days after rash onset.to 4 days after rash onset.
Strategy for sustainable Strategy for sustainable measles mortality reductionmeasles mortality reduction
1. Strong routine immunization 1. Strong routine immunization > > 90%90%• Reaching Every District StrategyReaching Every District Strategy
3. Surveillance3. Surveillance
2. Provide second opportunity for 2. Provide second opportunity for measles immunizationmeasles immunization• One time onlyOne time only “catch-up” campaign ( < 15 ) “catch-up” campaign ( < 15 )• “ “Follow-up” campaigns every 3-4 years ( < 5 ) Follow-up” campaigns every 3-4 years ( < 5 ) • Routine scheduled second dose / opportunity Routine scheduled second dose / opportunity
4. Improved case management4. Improved case management
Palestine
Bahrain
Measles Campaigns in EMRO through 2005
Preschool and school age (13)School age (5)Preschool age (1)
Not done (1)
Ongoing (2)
1963 Live attenuated and killed vaccines
1965 Live further attenuated vaccine
1967 Killed vaccine withdrawn
1968 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
Measles VaccineMeasles Vaccine CompositionComposition Live virusLive virus EfficacyEfficacy 95% (range, 90%-98%)95% (range, 90%-98%) Duration ofDuration of
ImmunityImmunity LifelongLifelong ScheduleSchedule 2 doses2 doses Should be administered with mumps and rubella as Should be administered with mumps and rubella as
MMR MMR
The seroconversion rate is 95% and the The seroconversion rate is 95% and the immunity lasts for at least 10 years or immunity lasts for at least 10 years or more, possibly lifelongmore, possibly lifelong
MMRV (ProQuad)MMRV (ProQuad)
Combination measles, mumps, rubella Combination measles, mumps, rubella and varicella vaccineand varicella vaccine
Approved children 12 months through 12 Approved children 12 months through 12 years of age (up to age 13 years)years of age (up to age 13 years)
Titer of varicella vaccine virus in MMRV Titer of varicella vaccine virus in MMRV is more than 7 times higher than is more than 7 times higher than standard varicella vaccinestandard varicella vaccine
MMR Vaccine FailureMMR Vaccine Failure
Measles, mumps, or rubella disease (or lack of Measles, mumps, or rubella disease (or lack of immunity) in a previously vaccinated personimmunity) in a previously vaccinated person
2%-5% of recipients do not respond to the first 2%-5% of recipients do not respond to the first dosedose
Caused by antibody, damaged vaccine, record Caused by antibody, damaged vaccine, record errorserrors
Most persons with vaccine failure will respond Most persons with vaccine failure will respond to second doseto second dose
Measles (MMR) Vaccine IndicationsMeasles (MMR) Vaccine Indications
All infants All infants >>12 months of age12 months of age Susceptible adolescents and adults Susceptible adolescents and adults
without documented evidence of immunitywithout documented evidence of immunity
Measles Mumps Rubella VaccineMeasles Mumps Rubella Vaccine
12 months is the recommended and 12 months is the recommended and minimum ageminimum age
MMR given before 12 months should not MMR given before 12 months should not be counted as a valid dosebe counted as a valid dose
Revaccinate at Revaccinate at >>12 months of age12 months of age
Second Dose of Measles VaccineSecond Dose of Measles Vaccine
Intended to produce measles immunity in Intended to produce measles immunity in persons who failed to respond to the first persons 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
Second Dose RecommendationSecond Dose Recommendation
First dose of MMR at 12-15 monthsFirst dose of MMR at 12-15 months Second dose of MMR at 4-6 yearsSecond dose of MMR at 4-6 years Second dose may be given any time Second dose may be given any time >>4 4
weeks after the first doseweeks after the first dose
MMR Adverse ReactionsMMR Adverse Reactions FeverFever 5%-15%5%-15%
RashRash 5%5%
Joint symptomsJoint symptoms 25%25% ThrombocytopeniaThrombocytopenia <1/30,000 <1/30,000 dosesdoses
ParotitisParotitis rarerare
DeafnessDeafness rarerare EncephalopathyEncephalopathy <1/1,000,000 <1/1,000,000 dosesdoses
MMR Vaccine and AutismMMR Vaccine and Autism
Measles vaccine connection first suggested Measles vaccine connection first suggested by British gastroenterologistby British gastroenterologist
Diagnosis of autism often made in second Diagnosis of autism often made in second year of lifeyear of life
Multiple studies have shown no associationMultiple studies have shown no association
MMR Vaccine and AutismMMR Vaccine and Autism
““The evidence favors a rejection of a causal The evidence favors a rejection of a causal relationship at the population level between relationship at the population level between MMR vaccine and autism spectrum MMR vaccine and autism spectrum disorders (ASD).”disorders (ASD).”
- Institute of Medicine, April 2001- Institute of Medicine, April 2001
MMR VaccineMMR VaccineContraindications and PrecautionsContraindications and Precautions
Severe allergic reaction to vaccine Severe 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
The use of live-attenuated vaccine for post-The use of live-attenuated vaccine for post-exposure prophylaxis is contraindicated.exposure prophylaxis is contraindicated.