Measles Pathogenesis and Clinical Features Respiratory transmission of virus



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Measles, Mumps and Rubella Ch 10, 11 & 12




Measles Pathogenesis and Clinical Features

  • Respiratory transmission of virus

  • Replication in nasopharynx and regional lymph nodes

  • Primary viremia 2-3 days after exposure

  • Secondary viremia 5-7 days after exposure with spread to tissues

  • Incubation period 10-12 days

  • Stepwise increase in fever to 103°F or higher

  • Cough, coryza, conjunctivitis

  • Koplik spots

  • 2-4 days after prodrome, 14 days after exposure

  • Maculopapular, becomes confluent

  • Begins on face and head

  • Persists 5-6 days

  • Fades in order of appearance







Measles Complications

  • Condition

  • Diarrhea

  • Otitis media

  • Pneumonia

  • Encephalitis

  • Hospitalization

  • Death



Measles Epidemiology

  • Reservoir Human

  • Transmission Respiratory Airborne

  • Temporal pattern Peak in late winter–spring

  • Communicability 4 days before to 4 days after rash onset



Measles Vaccine

  • Composition Live virus

  • Efficacy 95% (range, 90%-98%)

  • Duration of Immunity Lifelong

  • Schedule 2 doses

  • Should be administered with mumps and rubella as MMR, or with mumps, rubella and varicella as MMRV

  • 1941 - 894,134 U.S. cases

  • 1995 - 288 U.S. cases





Measles Vaccine Indications for Revaccination

  • Vaccinated before the first birthday

  • Vaccinated with killed measles vaccine

  • Vaccinated prior to 1968 with an unknown type of vaccine

  • Vaccinated with IG in addition to a further attenuated strain or vaccine of unknown type



Mumps

  • Acute viral illness

  • Parotitis and orchitis described by Hippocrates in 5th century BC

  • Viral etiology described by Johnson and Goodpasture in 1934

  • Frequent cause of outbreaks among military personnel in prevaccine era



Mumps Virus

  • Paramyxovirus

  • RNA virus

  • One antigenic type

  • Rapidly inactivated by chemical agents, heat, and ultraviolet light



Mumps Pathogenesis

  • Respiratory transmission of virus

  • Replication in nasopharynx and regional lymph nodes

  • Viremia 12-25 days after exposure with spread to tissues

  • Multiple tissues infected during viremia



Mumps Clinical Features

  • Incubation period 14-18 days

  • Nonspecific prodrome of myalgia, malaise, headache, low-grade fever

  • Parotitis in 30%-40%

  • Up to 20% of infections asymptomatic





Mumps Complications



Mumps Epidemiology

  • Reservoir Human Asymptomatic infections may transmit

  • Transmission Respiratory drop nuclei

  • Temporal pattern Peak in late winter and spring

  • Communicability Three days before to four days after onset of active disease



Mumps Outbreak, 2006

  • Source of the initial cases unknown

  • Outbreak peaked in mid-April

  • Median age of persons reported with mumps was 22 years

  • Highest incidence was among young adults 18-24 years of age, many of whom were college students

  • Transmission of mumps virus occurred in many settings, including college dormitories and healthcare facilities



Factors Contributing To Mumps Outbreak, 2006

  • College campus environment

  • Lack of a 2-dose MMR college entry requirement or lack of enforcement of a requirement

  • Delayed recognition and diagnosis of mumps

  • Mumps vaccine failure

  • Vaccine might be less effective in preventing asymptomatic infection or atypical mumps than in preventing parotitis

  • Waning immunity





Mumps Vaccine

  • Composition Live virus (Jeryl Lynn strain)

  • Efficacy 95% (Range, 90%-97%)

  • Duration of Immunity Lifelong

  • Schedule >1 Dose

  • Should be administered with measles and rubella (MMR) or with measles, rubella and varicella (MMRV)



Rubella

  • From Latin meaning "little red"

  • Discovered in 18th century - thought to be variant of measles

  • First described as distinct clinical entity in German literature

  • Congenital rubella syndrome (CRS) described by Gregg in 1941



Rubella Virus

  • Togavirus

  • RNA virus

  • One antigenic type

  • Rapidly inactivated by chemical agents, ultraviolet light, low pH, and heat



Rubella Pathogenesis

  • Respiratory transmission of virus

  • Replication in nasopharynx and regional lymph nodes

  • Viremia 5-7 days after exposure with spread to tissues

  • Placenta and fetus infected during viremia



Rubella Clinical Features

  • Incubation period 14 days

  • (range 12-23 days)

  • Prodrome of low-grade fever

  • Maculopapular rash 14-17 days after exposure

  • Usually quite mild







Epidemic Rubella – United States, 1964-1965

  • 12.5 million rubella cases

  • 2,000 encephalitis cases

  • 11,250 abortions (surgical/spontaneous)

  • 2,100 neonatal deaths

  • 20,000 CRS cases

    • deaf - 11,600
    • blind - 3,580
    • mentally retarded - 1,800


Congenital Rubella Syndrome

  • Infection may affect all organs

  • May lead to fetal death or premature delivery

  • Severity of damage to fetus depends on gestational age

  • Up to 85% of infants affected if infected during first trimester



Congenital Rubella Syndrome

  • Deafness

  • Cataracts

  • Heart defects

  • Microcephaly

  • Mental retardation

  • Bone alterations

  • Liver and spleen damage







Rubella Epidemiology

  • Reservoir Human

  • Transmission Respiratory Subclinical cases may transmit

  • Temporal pattern Peak in late winter and spring

  • Communicability 7 days before to 5-7 days

  • after rash onset Infants with CRS may shed virus for a year or more



Rubella - United States, 1966-2005

  • Rubella - United States, 1966-2005



Rubella Vaccine

  • Composition Live virus (RA 27/3 strain)

  • Efficacy 95% (Range, 90%-97%)

  • Duration of Immunity Lifelong

  • Schedule At least 1 dose

  • Should be administered with measles and mumps as MMR or with measles, mumps and varicella as MMRV



Rubella Vaccine Arthropathy

  • Acute arthralgia in about 25% of vaccinated, susceptible adult women

  • Acute arthritis-like signs and symptoms occurs in about 10% of recipients

  • Rare reports of chronic or persistent symptoms

  • Population-based studies have not confirmed an association with rubella vaccine



Vaccination of Women of Childbearing Age

  • Ask if pregnant or likely to become so in next 4 weeks

  • Exclude those who say "yes"

  • For others

    • explain theoretical risks
    • vaccinate


Vaccination in Pregnancy Study 1971-1989

  • 321 women vaccinated

  • 324 live births

  • No observed CRS

  • 95% confidence limits 0%-1.2%



Measles Mumps Rubella Vaccine

  • 12 -15 months is the recommended and minimum age (more effective at 15 months)

  • MMR given before 12 months should not be counted as a valid dose

  • 2nd dose at 4-6 years



MMR Adverse Reactions

  • Fever 5%-15%

  • Rash 5%

  • Joint symptoms 25%

  • Thrombocytopenia <1/30,000 doses

  • Parotitis rare

  • Deafness rare

  • Encephalopathy <1/1,000,000 doses



MMR Vaccine and Autism

  • Measles vaccine connection first suggested by British gastroenterologist

  • Diagnosis of autism often made in second year of life

  • Multiple studies have shown NO association



MMR Vaccine Contraindications and Precautions

  • Severe allergic reaction to vaccine component or following prior dose

  • Pregnancy

  • Immunosuppression

  • Moderate or severe acute illness

  • Recent blood product



Measles and Mumps Vaccines and Egg Allergy

  • Measles and mumps viruses grown in chick embryo fibroblast culture

  • Studies have demonstrated safety of MMR in egg allergic children

  • Vaccinate without testing



Measles Vaccine and HIV Infection

  • MMR recommended for persons with asymptomatic and mildly symptomatic HIV infection

  • NOT recommended for those with evidence of severe immuno- suppression



MMR Vaccines



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