brief introduction to epidemiology, epidemiological triad and prevention of measles, mumps & rubella.

1.  Izatty Lim
0308188
13 June 2014
EPIDEMIOLOGICAL
TRIAD
DISTRIBUTION PREVENTION

2.  Occurrence
o Worldwide
o interruption of transmission achieved in the United States & other parts of the
Western Hemisphere.
 Reservoir
o human disease
o no known animal reservoir
o asymptomatic carrier state has not been documented.
 Transmission
o primarily person to person via large respiratory droplets
o Airborne transmission via aerosolized droplet nuclei has been documented in closed
areas for up to 2 hours after a person with measles occupied the area.
 Incubation Period
o 7 – 18 days
 Communicability
o highly communicable, >90% secondary attack rates among susceptible persons.
o Infectious period: from 4 days before to 4 days after rash onset
o Maximum communicability during prodromal phase

3.  Agent
o Measles virus.
• only one antigenic type of measles
virus.
• rapidly inactivated by heat, light,
acidic pH, ether, and trypsin
• short survival time (<2 hours) in the
air or on objects and surfaces
 Host
o Human
• Unvaccinated young children &
pregnant women
• Poorly nourish
• insufficient vitamin A
• Weakened immune systems
 Environment
o Developing countries – Africa & Asia
o Countries with low per capita incomes and
weak health infrastructures
o Countries experiencing or recovering from a
natural disaster or conflict
o dry seasons in tropical zones
o Overcrowded places

4.  In developed countries during the pre-vaccine era,
o >90% of children acquired measles by age 15.
o Following implementation of routine childhood vaccination at age 12 to 15 months, the age
of peak measles incidence in the United States shifted to six months of age.
 Measles as a significant cause of morbidity and mortality
o In 2000, measles was estimated to cause approximately 31 - 39.9 million illnesses
worldwide with an estimated 733,000 - 777,000 deaths, making it the 5th most common
cause of death in children under five years of age.

6. Worldwide reported measles incidence rate per 100 000 population, 2004

7.  Occurrence
o worldwide.
 Reservoir
o human disease
o persons with asymptomatic infection can transmit the virus, but no
carrier state is known to exist.
 Transmission
o airborne transmission
o direct contact with infected droplet nuclei or saliva.
 Incubation Period
o 16 - 18 days
 Communicability
o Contagiousness similar to that of influenza & rubella
• less than that for measles & varicella
o Infectious period: from 3 days before to the 4th day of onset of
symptoms

8.  Agent
o Mumps virus
• One antigenic type
• rapidly inactivated by formalin,
ether, chloroform, heat, and
ultraviolet light
 Host
o Human
• Failure to be immunized
completely
• children between 2-12 years of
age
• Weakened immune system
 Environment
o Africa, general Indian subcontinent region, and
Southeast Asia- very low rate of vaccination
o Late winter & spring
o Small, enclosed room
o Crowded places

9.  Occurrence
o worldwide.
 Reservoir
o human disease
o Infants with congenital rubella syndrome(CRS) may shed rubella virus for an
extended period,
• But a true carrier state has not been describe.
 Transmission
o person to person via airborne transmission
o droplets shed from the respiratory secretions of infected persons
• asymptomatic cases
o no evidence of insect transmission
 Incubation Period
o 14 – 21 days
 Communicability
o only moderately contagious.
o most contagious when the rash first appears
o Infectious period: from 7 days before to 5–7 days or more after rash onset.
o Infants with CRS shed virus from body secretions for up to 1 year
• may transmit rubella to persons caring

10.  Agent
o rubella virus
• Do not require vector
• relatively unstable
• inactivated by lipid solvents, trypsin,
formalin, ultraviolet light, low pH, heat
 Host
o Human
• infants and young toddlers who have
not received the vaccine
• women of childbearing age do not
have immunity to the disease
 Environment
o WHO African and South-East Asian
regions- vaccine coverage is lowest
o Late winter early spring
o Small, enclosed room
o Crowded places
o Schools or day care centre
o Shopping mall

12.  Rubella
o Rubella vaccine (Meruvax)
o Keep distance from infected
person
 Measles
o Measles vaccine
• 2 doses
• 1st dose at age 12 -15 months
• 2nd dose at 4 – 6 years old
o Keep distance from infected
person
 Mumps
o Mumps vaccine (Paramyxovirus)
• Last at least 12 years
o Keep distance from infected
person
 Combined MMR introduced in Malaysia
o 2002

14.  Epidemiology
o https://sites.google.com/site/epidemiology12/measles
o https://sites.google.com/site/epidemiology12/rubella
o https://sites.google.com/site/epidemiology12/mumps
 WHO Health Topics
o http://www.emro.who.int/health-topics/measles/disease-and-epidemiology.html
o http://www.emro.who.int/health-topics/rubella/disease-and-epidemiology.html
o http://www.who.int/topics/mumps/en/
 Epidemiology and transmission of measles
o http://www.uptodate.com/contents/epidemiology-and-transmission-of-measles
 Vaccine Knowledge Project
o http://www.ovg.ox.ac.uk/measles
o http://www.ovg.ox.ac.uk/rubella
 Rubella Virus
o http://www.stanford.edu/group/virus/toga/2000/c.html
 WHO Incidence time series for Malaysia
o http://apps.who.int/immunization_monitoring/globalsummary/incidences?c=MYS
 History of Vaccine
o http://www.historyofvaccines.org/content/articles/mumps

15.  Epidemiology and Prevention of Vaccine-Preventable
Diseases
o http://www.cdc.gov/vaccines/pubs/pinkbook/meas.html
o http://www.cdc.gov/vaccines/pubs/pinkbook/rubella.html
o http://www.cdc.gov/vaccines/pubs/pinkbook/mumps.html
 Measles Prevention and Control in Malaysia
o http://jknns.moh.gov.my/v1/images/borang/cdc/r.Measles-
Prevention%20and%20Control%20in%20Malaysia.pdf
 Lippincott’s Guide to Infectious Diseases
 Harrison’s Infectious Diseases
o By Kasper, D. L., & Fauci, A. S. (2010)