Dr Leigh Martens

Understanding the causes of measles

By Christian Nordqvist

Measles is a highly infectious illness caused by the rubeola virus.

However, if measles enters an area where the people have never been exposed, the result can be devastating.

Vaccination prevents many cases of measles around the world. The World Health Organization (WHO) estimate that 2.6 million people who have not had the vaccine die of measles every year.

 

What is measles?

Measles is a viral disease that can spread rapidly.

Also known as rubeola or morbilli, measles is an endemic disease, meaning it is continually present in a community, and many people develop resistance.

It is an unpleasant condition but one that normally passes without treatment within 7 to 10 days.

After a bout of measles, a person gains immunity for the rest of their life. They are very unlikely to contract measles a second time.

 

Symptoms

Measles is often noticed through a breakout of spots.

The symptoms of measles always include fever and at least one of the three Cs:

• cough
• coryza, or runny nose
• conjunctivitis

Symptoms will appear about 9 to 11 days after initial infection.

Symptoms may include:

• runny nose
• dry hacking cough
• conjunctivitis, or swollen eyelids and inflamed eyes
• watery eyes
• photophobia, or sensitivity to light
• sneezing
• a reddish-brown rash
• Koplik's spots, or very small greyish-white spots with bluish-white centres in the mouth, insides of cheeks, and throat
• generalized body aches

There is often a fever. This can range from mild severe, up to 40.6 degrees Centigrade. It can last several days, and it may fall and then rise again when the rash appears.

The reddish-brown rash appears around 3 to 4 days after initial symptoms. This can last for over a week.

The rash usually starts behind the ears and spreads over the head and neck. After a couple of days, it spreads to the rest of the body, including the legs. As the spots grow, they often join together.

Most childhood rashes are not measles, but a child should see a doctor if:

• a parent suspects the child may have measles
• symptoms do not improve, or they get worse
• the fever rises to above 38º Centigrade
• other symptoms resolve, but the fever persists
• Complications from measles are fairly common. Some can be serious.
• People most at risk are patients with a weak immune system, such as those with HIV, AIDS, leukemia, or a vitamin deficiency, very young children, and adults over the age of 20 years.
• Older people are more likely to have complications than healthy children over the age of 5 years.
• Complications can include:
• diarrhoea
• vomiting
• eye infection
• respiratory tract infections, such as laryngitis and bronchitis
• difficulty breathing
• ear infections, which can lead to permanent hearing loss
• febrile seizures
• Patients with a weakened immune system who have measles are more susceptible to bacterial pneumonia. This can be fatal if not treated.

Complications

• The following less common complications are also possible:
• Hepatitis: Liver complications can occur in adults and in children who are taking some medications.
• Encephalitis: This affects around 1 in every 1,000 patients with measles. It is an inflammation of the brain that can sometimes be fatal. It may occur soon after measles, or several years later.
• Thrombocytopenia, or low platelet count, affects the blood's ability to clot. The patient may bruise easily.
• Squint: Eye nerves and eye muscles may be affected.
• Complications that are very rare but possible include:
• Neuritis, an infection of the optic nerve that can lead to vision loss
• Heart complications
• Subacute sclerosing panencephalitis (SSPE): A brain disease that can affect 2 in every 100,000 people, months or years after measles infection. Convulsions, motor abnormalities, cognitive issues, and death can occur.
• Other nervous system complications include toxic encephalopathy, retrobulbar neuritis, transverse myelitis, and ascending myelitis.
• Pregnancy

Measles during pregnancy can lead to miscarriage, early delivery, or low birth weight. A woman who is planning to become pregnant and has not been vaccinated should ask her doctor for advice.