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Dr Roger Henderson
Reviewed by Roger HendersonReviewed on 29.04.2024 | 7 minutes read

Measles is a highly contagious viral disease, and despite the availability of an effective vaccine there are now significant outbreaks occurring in the UK. Here at we know how concerned many of you are about this so in this article we look at various aspects of measles, including its symptoms, transmission, and the facts about vaccination.

What is measles?

Measles has been recognised as a human disease for centuries and records suggest that the earliest descriptions of measles date back to the 9th century. The virus responsible for measles, a member of the Paramyxoviridae family, was identified in the 20th century. Over the years, there have been widespread outbreaks with sometimes severe consequences, particularly among children.

How infectious is measles?

Measles is extremely infectious. Doctors talk about the ‘R number’ to describe how infectious something is – if this is below one, each case of an infection produces less than one other case, and so the number of people infected goes down. If the R number is greater than 1, each infected person affects at least one more so the number of infected people goes up. With COVID-19, the R numbers discussed are typically below 5, therefore 1 person would infect 5 other people. The R number for measles is between 12 and 18 so it can be seen just how infectious it is. If we had 300 people start with the infection (roughly the size of a lecture hall), it could lead to spreading to up to 5400 people, which is more than the capacity of the largest theatre in the UK.

How is measles spread?

Measles is mainly spread through respiratory droplets infected with the measles virus produced when someone with it talks, coughs, or sneezes. The virus is highly contagious and can remain active in the air and on surfaces for up to two hours. If a person who is infected with measles coughs or sneezes and the respiratory droplets land on surfaces or objects, individuals who touch those contaminated surfaces and then touch their face, particularly their mouth, nose, or eyes, can become infected.

What are the symptoms of measles?

Measles is contagious from approximately four days before the onset of the characteristic rash to four days after the rash appears, which means that someone infected with measles can spread the virus even before they are aware of their illness. The time from exposure to the virus to the onset of symptoms (incubation period) is usually around 10 to 12 days and people who have not been vaccinated against measles and have not previously had the disease are highly susceptible to infection. Infants, pregnant women, and individuals with compromised immune systems are particularly vulnerable to severe complications.

Although measles symptoms typically follow a predictable pattern, progressing through several stages it's important to say that not everyone with measles will experience all of these symptoms, and the severity of symptoms can vary. The common symptoms associated with measles are:

  1. A prodromal (pre-rash) stage: Measles often begins with a high fever, which can spike as high as 40°C, along with a persistent, dry cough and a runny or stuffy nose. Before the characteristic measles rash appears, small white spots known as Koplik's spots may appear inside the mouth - these are tiny, irregularly-shaped white or bluish-white dots on a red background.
  2. A rash: a measles rash typically appears 2 to 4 days after the onset of initial symptoms and usually starts on the face and then spreads down the body, including the trunk, arms, and legs. This rash consists of red, flat or raised spots that may merge as the rash progresses, giving a blotchy appearance and is often accompanied by a high fever that can be persistent and increase during the initial days of the illness. The rash then fades after 5-7 days.
  3. Sensitivity to light (photophobia): measles can cause sensitivity to light, and individuals with the infection may find bright lights uncomfortable.

For most people, these symptoms will disappear within 7-10 days.

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What are the complications of measles?

Measles is generally a self-limiting disease, and most people recover without any significant complications. However, in some cases, especially among certain populations, measles can lead to severe and potentially life-threatening complications that can arise during or after the acute phase of the illness. In developed countries, 10-20 out of 100 people who catch measles will experience some sort of complication. Some of the common complications associated with measles include:

Pneumonia (inflammation of the lungs)

Pneumonia is a complication affecting between 1-6 people in 100 cases of measles and is a leading cause of measles-related deaths, particularly in young children and individuals with compromised immune systems.

Ear infections

Affecting 7-9 people in 100 with measles, these occur as a result of the measles virus affecting the middle ear. These ear infections can lead to pain and, if left untreated, may result in deafness that can be permanent.


Diarrhoea affects around 2 in 25 of cases and may cause dehydration.

Bronchitis and croup

Measles can cause inflammation of the airways (bronchitis) and the voice box (larynx), leading to a condition known as croup, characterised by a distinctive barking cough and which may also cause breathing difficulties.

Central nervous system

About 1 in 200 cases of measles will suffer from convulsions (seizures) and about 1 in 1000 cases will have encephalitis - a severe complication of measles, involving inflammation of the brain. It can occur during or after the acute phase of the illness and may result in neurological symptoms and long-term problems with the brain. Subacute sclerosing panencephalitis (SSPE) affects around 1 in 25,000 people with measles. This is approximately 1 person inside a completely packed O2 Arena London. It is 16 times more common in children under the age of 1 who develop measles. It develops after someone has had the infection – usually around 7 years later – but can occur as late as three decades afterwards and is invariably fatal.


Measles is a leading cause of blindness globally, often in children who are deficient in vitamin A.

Pregnancy complications

Pregnant women who contract measles may be at an increased risk of complications, including premature birth, low birth weight, and maternal complications.

The best way to prevent measles and its complications is through vaccination. The measles, mumps, and rubella (MMR) vaccine is highly effective in preventing measles and its associated complications,

Measles vaccination

Vaccination has proven to be a highly effective tool in preventing measles. The measles, mumps, and rubella (MMR) vaccine, introduced in the 1960s, has played a huge role in reducing the global burden of measles and provides long-lasting immunity.

The MMR vaccine is the primary vaccine used to protect against measles in the UK. This vaccine also provides protection against mumps and rubella.

The MMR vaccine is typically given in two doses. The first dose is usually administered to children around their first birthday, and the second dose is given before they start school (usually between 3 and 4 years old).

Parents sometimes refuse the measles vaccine for their child because they believe that the MMR vaccine is linked to autism.  This is because of a paper published in the medical journal The Lancet in 1998 that suggested the MMR vaccination was associated with behavioural regression and autism. Although the article was disputed and then retracted, MMR uptake rates started to fall as a result. It was later revealed that the doctor who suggested this had significant conflicts of interest as well as interests in single vaccines that had not been declared, and was subsequently removed from the medical register. Their suggestion has now been categorically disproved.

How is measles treated?

There is no specific medication available that kills the measles virus, so treatment aims to reduce any symptoms that are present until the infection clears away. For most people, simply resting and treating any fever is enough before the symptoms clear within 7-10 days. General measures include:

  • drinking regularly to keep well hydrated – if children find this difficult then giving them ice lollies can help here, as well as helping to keep them cool

  • taking paracetamol or ibuprofen to help keep any high temperature down and reducing any aches and pains

  • resting as much as possible - sleep and recovery

Antibiotics are of no use in treating measles – these do not have any effect on a virus – but if you develop a secondary problem such as a chest or ear infection they may be prescribed to treat these.

When should I see a doctor?

If you feel that you or your child may have measles, phone your doctor to discuss this first – they may want to do an examination but because measles is so infectious they may arrange a time when there are few other patients in the waiting room. Speak with your doctor as soon as possible if worrying symptoms develop such as:

  • drowsiness

  • dehydration (a child may pass little or no urine, have a dry mouth or tongue, or not have drunk much)

  • difficulty in breathing

  • seizures (fits)

Remember - it's essential to seek medical attention if someone is suspected of having measles, particularly if they have not been vaccinated or if they are part of a high-risk group. The early detection and proper medical care can help manage the symptoms of measles and reduce the risk of complications from it. Because of the highly contagious nature of measles, individuals with it are advised to stay isolated to prevent further transmission of the virus.

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Dr Roger Henderson
Reviewed by Roger Henderson
Reviewed on 29.04.2024
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