How is Kawasaki disease diagnosed?
The diagnosis of Kawasaki disease does not consist of one single test. The doctor is likely to confirm the disease through examining your child’s symptoms by means of a physical examination.
Your child is likely to be diagnosed with Kawasaki disease if he or she has a temperature of 38℃ (100.4℉) or higher as well as four or more of the below key symptoms:
- Changes in the mouth or throat – These changes include cracked or dry lips and strawberry tongue (red, bumpy and inflamed tongue).
- Conjunctival infection present in both of the eyes – This is a condition where the white areas of the eyes are swollen and red.
- Changes in the feet and hands – These changes include painful or swollen feet or hands, as well as peeling or red skin on the palms or soles.
- Lymph nodes – The lymph nodes will become swollen located in the neck.
- Rash – This rash will typically develop in the genital regions and then spread to the torso and limbs.
Your child’s skin on his or her toes and fingers may become hard or red and their feet and hands may also swell up. It is also possible for your child’s feet and hands to become painful and tender when touched or walked on, thus making walking or crawling difficult.
Some cases of Kawasaki disease are diagnosed especially if your child does not have at least four of the key symptoms of Kawasaki disease. This may be a case in incomplete or atypical Kawasaki disease.
It is possible that your child may require additional tests in order for a number of other conditions that may be causing the symptoms to be ruled out.
The possible conditions that may be causing similar symptoms include:
- Measles – This is an extremely infectious virus that results in a fever as well as distinctive reddish-brown spots on the body that manifest in the form of a rash.
- Scarlet fever - This condition is a bacterial infection seen commonly in children and is characterised by a pink and red rash on the body.
- Glandular fever – This refers to a viral infection that results in swollen lymph nodes (glands) and fever.
- Viral meningitis – This condition infects the protective membranes surrounding the spinal cord and brain and results in the inflammation of these areas.
- Toxic shock syndrome (TSS) – This life-threatening condition occurs as a result of a number of bacterial infections and is rarely seen.
- Stevens-Johnson syndrome – This is an extremely severe allergic reaction to certain medications.
- Lupus – This is an autoimmune disorder that can result in a number of symptoms which include a rash, joint pain and fatigue.
There are a number of tests that can be conducted during the initial seven to ten days of Kawasaki disease that aid in an accurate diagnosis, these include:
- Blood tests – A blood test will involve your doctor drawing a sample of blood from the affected child and sending it to a laboratory for analysis. A blood test for Kawasaki disease will include one that looks at a number of white blood cells or the platelet count.
- If the white blood cells are increased this often indicates the presence of infection as the WBC (white blood cells) form a vital part of the immune system in helping the body to fight off infection and illness.
- A platelet count measures the number of platelets present in the blood, these are blood clotting agents which the body uses to stop an injury site from bleeding. If the platelet amount is higher than normal, this may indicate the presence of a blood clot.
- Urine sample – This test will allow for the doctor to examine the urine for white blood cells.
- Lumbar puncture – This procedure involves inserting a needle into the lower area of your child’s spine in order for a sample of the spinal (cerebrospinal) fluid to be taken. This test is able to detect severe infection such as meningitis or disorders affecting the central nervous system (CNS).
If these tests are conducted individually, they may not be conclusive, however, when they are combined with the identification of a number of the symptoms listed above, this can help in confirming the diagnosis.
As previously stated, the complications of Kawasaki disease will normally have an effect on the heart. This may mean that your child needs additional tests to be conducted in order for the function of their heart to be monitored.
These tests may include:
- ECG (electrocardiogram) – This procedure involves measuring the heart’s activity of electric pulses through the use of electrodes (flat and round metal discs with sticky pads that stick to the skin) that are attached to the legs, arms and chest. This will aid in identifying any damage done to the heart or issues with the rhythm of the heart.
- Echocardiogram – This procedure uses sound waves to create images from the inside of the heart that allow the specialist to detect any issues with the function or structure of the heart.
There are a number of heart abnormalities that may be detected during the first two weeks of Kawasaki disease, which is the acute phase of the condition. Some of these heart conditions include:
- Myocarditis – This is a condition that refers to the inflammation of the heart muscle
- Tachycardia – This condition refers to an abnormally fast resting heart rate
- Pericardial effusion – This refers to fluid collecting in the heart
In roughly 25 percent of children with Kawasaki disease, the child’s blood vessels found around their heart, known as the coronary arteries, are slightly widened.
In the majority of cases, these abnormalities will resolve within six to eight weeks from the initial onset of symptoms, although, it is also possible for further complications to arise during this time.