What is measles?
Measles is an acute and serious infection caused by the measles virus. It causes a rash illness, with cough, runny nose, conjunctivitis and high fever. The disease is very infectious. Before vaccination was available the infection most commonly affected young children. However, anyone can catch measles at any age if they are not protected against the infection, either from vaccination or as a result of previous infection.
How is measles transmitted?
Measles is transmitted through direct contact with an infected person or through the air when the infected person coughs or sneezes. It is so infectious that it can be transmitted to people who may breathe in the air-borne virus upon entering a room where an individual with measles was coughing up to two hours before.
When is measles most infectious?
The most infectious period of the measles illness is during the four days before and four days after rash onset. During the four days before rash onset the person with measles will usually not know that this is the illness they have. During this time they can easily transmit the virus. Once the rash develops people may know what they have and will normally be at home recovering from the illness. During this time they are less likely to transmit the virus (although still infectious) because they are at home. However, people in the house if not protected against measles are at risk during this time. During the infectious period, even trivial contact may be sufficient for the virus to spread.
How soon after contact with measles virus does disease develop?
The incubation period (the time from exposure to the virus until the first symptoms develop is typically 10-12 days. From exposure to rash onset averages 14 days (7-18 days).
What are the symptoms of measles?
The first stage of measles includes irritability, a runny nose, conjunctivitis (red eyes), a hacking cough and an increasing fever that comes and goes. These symptoms usually last 2-4 days (occasionally up to 7 days). The rash starts from day 4. It usually starts on the forehead and spreads downwards over the face, neck and body. The rash consists of flat red or brown blotches, which can flow into each other. It lasts about 4-7 days. There can also be diarrhoea, vomiting and abdominal pain.
Are complications common with measles?
Yes, complications are quite common. They include a severe cough and breathing difficulties (croup), ear infections (1 in 20), viral and bacterial lung infections (pneumonia) (1 in 25), and eye infections (conjunctivitis). Most of the complications are caused by secondary bacterial infections, which can be treated with antibiotics. More serious problems involve the nervous system and are rarer. Inflammation of the brain (acute encephalitis) occurs 2-6 days after the rash has appeared. Less than 1 in 1,000 measles cases is affected in this way, but 25% of those affected are left with brain damage. SSPE (subacute sclerosing pan-encephalomyelitis) is the most severe complication of measles. It usually occurs years after the initial illness and is a slowly progressive brain infection. SSPE starts with intellectual impairment and deteriorates to seizures and eventually death. It is, however, very rare occurring in less than 1 in 100,000 cases of measles. Measles infection during pregnancy can result in the loss or early birth of the baby.
Severe disease and complications are most likely in infants under 12 months, those with weakened immune systems, and the malnourished.
Can measles be prevented?
In Ireland a vaccine that contains measles-mumps-rubella vaccines as a combined vaccine (called MMR) is used to prevent measles (as well as mumps and rubella). The vaccine produces an inapparent or mild infection that does not cause disease or harm to the child. The MMR vaccine stimulates antibodies in the child to protect against the wild measles virus if the child is exposed to the virus.
When was measles vaccine first introduced in Ireland?
Measles immunisation was introduced in Ireland in 1985, and from 1988 the MMR vaccine was used to replace the single measles vaccine. Since that time the uptake of MMR vaccine has reached most children and the risk of measles infection in Ireland has decreased over time.
Have any large measles outbreaks occurred since the MMR vaccine was introduced?
In 1993/1994, there was a large increase in the number of cases of measles identified in Ireland, which was due to not enough children being immunised to prevent spread of the disease.
Another large measles outbreak occurred in Ireland in 2000, with more than 1600 cases reported and three deaths in young children were associated with this outbreak. Since 2000 other smaller outbreaks have been reported in different parts of the country. These outbreaks occur among children or young adults who are either unvaccinated or under-vaccinated (one dose of MMR only). The outbreaks have been prevented from further spread by offering vaccine to those individuals who need additional doses of MMR vaccine.
How effective is MMR in preventing measles?
MMR vaccine can prevent measles in over 95% of children given MMR at or after 12 months of age. For those that fail to respond to the first dose (about 2-5%) a second dose provides protection to more than 99% of those immunised.
When is MMR vaccine given in Ireland?
The first dose is given at 12 months and the second dose at 4-5 years of age. MMR vaccine can also given to those who need it (not immune) at any age if they need it for travel, for work or to protect vulnerable children or adults.
Is MMR contraindicated for anyone?
The administration of MMR vaccine is contraindicated if an individual has any of the following
- Anaphylaxis (severe, potentially life-threatening allergic reaction) to any of the vaccine constituents
- Significantly immunocompromised persons, such as those with untreated malignant disease and immunodeficiency states other than HIV infection, and those who are receiving immunosuppressive therapy, high-dose x-ray therapy and current high-dose systemic corticosteroids
- Pregnancy. Furthermore pregnancy should be avoided for one month after MMR.
What is the uptake of MMR in Ireland?
The uptake of MMR at 24 months and among school children has improved in recent years, thereby decreasing the risk of measles in Ireland. Uptake data by HSE region and Local Health Office area is available on the HPSC website. Some children/people are still unvaccinated and are at risk of measles.
What should I do if I think my child has measles?
Keep your child at home if you think that he/she might have measles. Call your GP so that he/she can see your child at a time/place when no one else is there (to avoid infecting others). Your GP will also organise a test to confirm the diagnosis – this is usually done by using a small swab that takes a sample of the oral fluid from the child. If any complications develop the GP will prescribe antibiotics if needed for bacterial infections that can develop after the measles infection.
Are all cases of measles reported to Public Health?
Yes, measles is a notifiable disease (under Infectious Disease legislation) and all cases are reported to Departments of Public Health for investigation and risk assessment. The doctor/nurse from the HSE contacts all cases (or parents) to identify the source of the measles infection and risk of spread to others. They provide advice on how to prevent transmission to others.
For more information on MMR vaccine see the HSE immunisation website http://www.hse.ie/eng/health/immunisation/
Last updated: 9 February 2015
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