Diagnosis

There's no single test to diagnose Kawasaki disease, but there are some key signs that suggest a child may have this condition.

The National Institute for Health and Care Excellence (NICE) states that your child may have Kawasaki disease if they have:

• a high temperature for 5 days or longer
• at least 1 other key symptom

These symptoms include:

• conjunctival infection in both eyes – where the whites of your child's eyes are red and swollen without fluid leaking from their eyes
• changes to the mouth or throat – such as dry, red, cracked lips, a red, swollen tongue, or red inside the mouth or at the back of the throat
• changes to the hands and feet – such as swollen or painful hands or feet, or red or peeling skin on the palms of the hands or the soles of the feet
• a rash
• swollen lymph nodes in the neck

The skin on your child's fingers or toes may become red or hard, and their hands and feet may swell up.

Your child's hands and feet may also be tender and painful to touch or put weight on, so they may be reluctant to walk or crawl.

Children under 1 year of age may not have as many of the key symptoms compared with older children.

Read more about the symptoms of Kawasaki disease.

Sometimes, a child may be diagnosed with Kawasaki disease if they have a high temperature and only 1 key symptom, or if the high temperature has only lasted 4 days.

It’s also possible for a child with Kawasaki disease to have symptoms that appear and disappear throughout the illness.

Tell the doctor assessing your child if your child has recently had symptoms of Kawasaki disease but no longer has them.

Tests

Your child may need to have tests to rule out other conditions that could be causing their symptoms.

Possible conditions your child could have include:

• scarlet fever – a bacterial infection that causes a distinctive pink-red rash
• toxic shock syndrome – a rare, life-threatening bacterial infection
• measles – a highly infectious viral illness that causes a fever and distinctive red-brown spots
• glandular fever – a viral infection that can cause a fever and swollen lymph glands
• Stevens-Johnson syndrome – a very severe allergic reaction to medicine
• viral meningitis – an infection of the protective membranes that surround the brain and spinal cord (meninges)
• lupus – an autoimmune condition that can cause a range of symptoms, including fatigue, joint pain and a rash

Several tests can also be carried out to help support a diagnosis of Kawasaki disease.

These include:

• a urine sample – to see whether it contains white blood cells
• blood tests – such as a white blood cell count or platelet count
• a lumbar puncture – a sample of cerebrospinal fluid is taken by inserting a needle between the vertebrae of the lower spine

Individually, these tests may not be conclusive, but when combined with some of the key symptoms of Kawasaki disease, they can help confirm a diagnosis.

Heart problems

Complications of Kawasaki disease usually affect the heart. This means your child may need some tests to check their heart is functioning normally.

These must include:

• an electrocardiogram (ECG) – which measures the heart's electrical activity using flat metal discs (electrodes) attached to the arms, legs and chest; an ECG can identify damage to the heart or problems with the heart's rhythm
• an echocardiogram – where high-frequency sound waves are used to produce images of the heart, which can confirm whether there are any problems with the heart's structure or function

During the acute phase of Kawasaki disease (weeks 1 to 2), several heart abnormalities may be identified.

These could include:

• a rapid heart rate (tachycardia)
• a collection of fluid in the heart (pericardial effusion)
• inflammation of the heart muscle (myocarditis)
• coronary artery swelling (aneurysms)

Read more about the complications of Kawasaki disease.