Measles

24 February 2012

Key facts

  • Measles is a highly contagious disease that causes severe morbidity and death
  • Measles vaccine is highly effective: two doses protect almost all children from infection, and immunity is long lasting
  • Almost all children should be vaccinated against measles; contraindications to vaccination include prior anaphylactic reactions to neomycin, gelatin or other components of the vaccine, and severe immuno-compromise; vaccination of persons with high fever or signs of severe illness and pregnant women should be postponed
  • The Western Pacific Region has made great progress towards its goal of measles elimination by 2012, having reduced incidence to 12 cases per million population in 2011; achieving the goal will require additional efforts and political commitment.

Measles and its Complications

  • Measles virus (Morbillivirus) is a single-stranded RNA virus in the Paromyxoviridae family.
  • The initial symptoms of measles are high fever and cough, conjunctivitis, and/or coryza (rhinorrhea, or runny nose)
  • The characteristic rash (red spots) usually appears 3-4 days after the initial symptoms, 10-14 days after infection.
  • The rash spreads from the face, ears and neck to the trunk and then the limbs over 3 to 4 days
  • The risk of developing complications varies, being much higher among children less than 5 years old, living in overcrowded areas, who are undernourished (especially with vitamin A deficiency) and who have immune deficiencies such as advanced HIV infection
  • Death from measles can occur in as many as 5-10% of infected young children in developing countries
  • Ear infections (otitis media) occur in 5%-15% of cases and pneumonia in 5%-10% of cases.
  • In developing countries, persistent diarrhoea may also occur
  • Xerophthalmia, or dry eyes, can lead to corneal ulceration and blindness in vitamin A deficient persons.
  • Encephalitis occurs in approximately 1 of every 1000 cases. Those cases that do not die from encephalitis are often left with permanent brain damage.
  • Sub-acute sclerosing panencephalitis (SSPE), a progressive infection of the central nervous system, takes several years to develop and occurs in 1 of every 10,000-100,000 cases

Transmission

  • Measles affects only humans.
  • Spread is from person-to-person primarily by large respiratory droplets through airborne spread
  • Measles is the most infectious of diseases: secondary attack rates among susceptible persons may be 90% or greater
  • A person with measles can infect others from four days before to four days after rash onset

Treatment

  • Children diagnosed with measles should receive two doses of vitamin A supplements, the first dose at the time of diagnosis and the second 24 hours later.
  • Vitamin A helps prevent eye damage, blindness and other complications including death.
  • Complications from measles also can be prevented by good nutrition, adequate fluid intake and, in the case of diarrhoea and/or vomiting, treatment of dehydration with WHO-recommended oral rehydration solution.
  • Antibiotics may be given to treat eye and ear infections, and pneumonia.

Vaccine

  • Licensed in many countries since 1963; now universally available.
  • Made from a live attenuated virus – a weakened form of the natural (‘wild’) measles virus
  • Derived from any one of several strains (e.g., AIK-C, Edmonston Zagreb, Moraten, Schwarz, Shanghai 191), but all have similar effectiveness and risk of adverse reactions
  • Administered as monovalent measles vaccine or in combination with rubella, mumps or varicella vaccines, in various combinations.
  • Immune responses to each vaccine antigen and vaccine-associated adverse reactions are largely unchanged regardless of the type of combination.
  • Some studies indicate that fever, rash and febrile seizures after immunization may be more common with measles, mumps, rubella and varicella vaccine (MMRV) than when MMR and varicella vaccine are given simultaneously at separate sites.

Immunization safety

  • Side-effects include slight pain and tenderness at the sight of injection within 24 hours of vaccination, sometimes followed by mild fever and lymphadenopathy.
  • Common adverse reactions include high fever (39.4°C or greater) lasting 1-2 days in up to 5% of persons vaccinated, and can cause febrile seizures in 1 of every 3000 persons.
  • Transient rash may occur in approximately 2% of persons vaccinated
  • Both high fever and rash occur 7-12 days after vaccination when the peak of vaccine virus replication occurs.
  • Rare adverse reactions include thrombocytopenic purpura in 1 of every 30,000 persons vaccinated, and anaphylaxis in 1 of every 100,000 persons vaccinated.
  • No scientific evidence exists to demonstrate an increased risk of neurologic disorders (e.g., Guillan Barre Syndrome), inflammatory bowel disease or autism following measles vaccination.

Vaccine effectiveness

  • Many studies have evaluated measles vaccine effectiveness at different ages, with varying results.
  • Among 44 studies of children vaccinated between 8 and 9 months of age, a median of 89.6% seroconverted (interquartile range [IQR] 82, 95).
  • Among 21 studies of children vaccinated at 11-12 months of age, a median of 99% seroconverted (IQR 80, 100)†.
  • Studies on revaccination of children that failed to seroconvert after the first dose of measles vaccine show that almost all (median proportion 97%, IQR 87, 100) seroconvert after a second dose.
  • Vaccine effectiveness is reduced if the vaccine is damaged by heat or light.
  • Immunity derived from measles vaccination is long lasting; with neutralizing antibodies persisting for 26-33 years. However, it is not known whether a single dose of measles vaccine provides life long protection in the absence of natural boosting by exposure to measles virus.

Measles elimination in the Western Pacific Region

  • The Regional Committee of the Western Pacific resolved to eliminate measles in 2003, established the 2012 target year in 2005, and reaffirmed the goal in 2010.
  • Measles elimination is defined as the absence of endemic measles transmission in a defined geographical area (e.g. country or region) for at least 12 months in the presence of a well performing surveillance system††.
  • Measles virus importations and limited transmission will likely occur following elimination of endemic transmission until measles is eliminated in other parts of the world.
  • Strategies for measles elimination include:
    • achieving and maintaining 95% population immunity against measles virus in each birth cohort through routine and/or supplementary immunization activities (SIAs);
    • sensitive and timely case-based surveillance for measles;
    • access to an accredited laboratory to confirm suspected cases and identify virus.

Status of measles elimination in the Western Pacific

  • Over 300 million persons were immunized against measles in the Region through vaccination campaigns from 2003 to 2011.
  • Routine first-dose measles coverage for the Region was 96% in 2010
  • Measles surveillance performance has consistently improved over the past several years, increasing the ability of countries to monitor progress towards elimination and rapidly detect and respond to residual measles virus transmission.
  • All but one national measles laboratory in the Region is accredited by WHO.
  • Measles incidence in the Western Pacific Region during 2011 was at an all-time low, with only 12 confirmed cases reported for every million population.
  • Vaccination campaigns during 2011 in Cambodia, China, the Lao People's Democratic Republic, Papua New Guinea, and the Philippines will dramatically reduce measles virus transmission in 2012, bringing the 2012 elimination goal within reach.

Global measles elimination

  • The Measles Initiative (www.measlesinitiative.org) is a partnership launched in 2001 and led by the American Red Cross, United Nations Foundation, U.S. Centers for Disease Control and Prevention, UNICEF and WHO; the partners are committed to reducing measles deaths worldwide and supporting measles elimination activities.
  • From 2001 to 2010, more than one billion children living in high-risk countries around the world were vaccinated against measles through supplementary immunization activities, averting an estimated 5 million deaths.
  • Five of the six WHO regions have measles elimination goals; the sixth (the South-East Asia Region) is likely to establish an elimination goal soon, resulting in a de facto global eradication goal:
    • at least 90% coverage with first dose of measles vaccine nationally and 80% in every district
    • reduction in measles deaths by 95% compared to 2000;
    • reduction in measles incidence to less than 5 cases per million population;

Measles elimination, child survival, and health systems

  • Measles vaccination coverage is one of three indicators for achieving Millennium Development Goal 4 – to reduce by 2/3, between 1990 and 2015, the under five mortality rate.
  • Prevention of measles infection prevents the increased susceptibility to and mortality from pneumonia and diarrhoea that lasts for months following infection; diarrhoea and pneumonia cause 36% of deaths among children under 5 years old globally, and 31% of all under five deaths in the Western Pacific Region.
  • The need to achieve 95% coverage with two doses of measles vaccine requires programme managers at every level to re-focus efforts on strengthening routine immunization service coverage and quality to reach everyone in a timely manner, especially the poor and marginalized.
  • Administering a second dose of measles vaccine during the second year of life creates a platform for other interventions such as a 4th dose of diphtheria, pertussis and tetanus and polio vaccines, vitamin A, de-worming medicine, and growth monitoring
  • Establishing school-entry immunization requirements provides an opportunity to ensure fully immunized status of children with all antigens, decreasing child absenteeism from school and parental absenteeism from work, and strengthening collaboration between health and education ministries, and establishing relationships that will help promote school health overall
  • Supplementary immunization activities (SIAs) provide opportunities to improve health systems through improved microplanning, vaccine, logistics and staff management, refresher training, monitoring, supportive supervision and programme evaluation.
  • SIAs also provide opportunities to improve child health through administering other vaccines, nutritional supplements such as vitamin A, deworming medicine, insecticide treated bednets and other interventions.
  • SIAs are an instrument of equity, providing life saving interventions for the poor and marginalized.
  • Measles elimination also strengthens immunization and health systems by building nation-wide capacity to report, manage, analyze, interpret and feedback programme monitoring and surveillance data.

† World Health Organization. The immunological basis for immunization series, vol. 7: Measles - Update 2009; Geneva: WHO 2009

†† World Health Organization. Monitoring progress towards measles elimination, Wkly Epidemiol Rec 2010; 85:490–4.

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Last update:

25 July 2013 13:09 CEST