Measles Pathogenesis and Clinical Features Respiratory transmission of virus

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