…        Measles occurs throughout the world

…        Humans are only host / No animal reservoir

…        Transmission is person to person, via airborne aerosolized respiratory droplets

…        Occurs primarily in late winter and spring

…        Highly communicable, especially from 4 days prior to rash onset to 4 days after onset

 

National Trends:Ý

ÝÝÝÝÝÝÝÝÝÝÝ

…        Before 1963 ñ Approximately 500,000 reported cases and 500 deaths per year

ÝÝÝÝÝ Epidemics every 2-3 years

ÝÝÝÝÝ Estimated case load around 3-4 million per year

ÝÝÝÝÝ 90% of population had measles before age 15

ÝÝÝÝÝ Highest incidence in 5-9 year olds; 50% reported cases in thisÝÝ

ÝÝÝÝÝÝÝÝ group

ÝÝÝÝÝÝÝÝÝÝÝ ** 1963 ñ Vaccine Introduced

…        After 1963 --ÝÝ Incidence drops more than 98%

ÝÝÝÝÝ Epidemic cycle halts

ÝÝÝÝÝ Case load drops year by year; by 1983 only 1,497 cases

ÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝ ÝÝÝÝÝÝÝÝ reportedÝÝÝ

ÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝ ÝÝÝÝÝ Incidence increases 1983-1986, to 6,282 cases reported in 1986

ÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝÝ ÝÝÝÝÝÝÝÝÝ -- drops again 1987-1988 to approx. 3,500 cases/yr. reported

ÝÝÝÝÝÝÝÝÝÝÝ ** 68% of cases in school children 1985-86 among vaccinated children ñ

ÝÝÝÝ leads to recommendation of second dose upon school entry

…        1989 ñ 1991 ñ Dramatic resurgence of cases; total of 55,622 reported in 3 yrs.

ÝÝÝÝÝ 45% in children < 5 yrs.

ÝÝÝÝÝ Incidence highest for Hispanics and Blacks, lowest for non-Ý

ÝÝÝÝÝÝÝÝ Hispanic Whites

ÝÝÝÝÝ Total of 123 Measles associated deaths reported in this period;

ÝÝÝÝÝÝÝÝ 90% of fatal cases had no history of vaccination

ÝÝÝÝÝ Primary cause of resurgence determined to be low vaccine

ÝÝÝÝÝÝÝÝ coverage

…        1993 ñ 1999 ñ Extensive vaccination efforts lead to rapid decline in incidence

ÝÝÝÝÝ Fewer than 500 cases/yr. reported most years since 1993

ÝÝÝÝÝ Most cases due to importation

ÝÝÝÝÝ Transmission in U.S. seems to have been interrupted

ÝÝÝÝÝ Small outbreaks in unvaccinated preschool populations, among

ÝÝÝÝÝÝÝÝ vaccinated children, and among college students

ÝÝÝÝÝÝ Larger outbreaks only in populations that refuse vaccinationÝ

ÝÝÝÝÝÝÝÝÝ (Christian Scientists, some populations in Utah and Nevada)

 

ÝÝÝÝÝÝÝÝÝÝÝ * Reported Cases of Measles in Rhode Island, 1989-1997