Kawasaki Disease
A lot has been in the news lately about a ‘Kawasaki-like’ illness affecting children that may have had Covid-19. Most people are probably wondering what Kawasaki actually is, besides a motorcycle. Pediatricians are very familiar with it as one of those diseases that are talked about over and over, but we actually hardly ever see.
What is Kawasaki disease?
It is an inflammation of the vessels of the body. This means that the veins and arteries that bring blood to and from various areas of the body are swollen and irritated, which can cause several different problems. In Kawasaki, there is a specific group that show up.
*First, there is always fever with no obvious cause for at least 5 days, but can continue for up to two weeks.
*Then, must have at least four of these: red eyes without any drainage; cracked lips and/or red tongue; red rash that can look different depending on the patient, but never has blisters; a large node on one side of the neck; red and sometimes swollen palms and soles and/or peeling of the skin around the nails.
Some kids can also have irritation of the heart muscle, or pain with or without swelling of the joints, among with some other rare symptoms.
The most concerning problem is that it can permanently affect the coronary arteries in 25% of the affected children. Coronary arteries are the blood vessels that supply blood to your heart muscles so your heart can pump effectively. Luckily, if treated within the first 7-10 days of illness, the risk can go from 25% to 2%.
There is a very small risk of death, 0.2%, mostly due to heart complications.
How common is it?
Not very common, but the risk can vary by race – with asian children the most at risk, and age – most children are below 5 years old. There also appears to be a seasonal component, with more cases seen in the winter/spring. Approximately 3,000-5,000 children in the US develop Kawasaki disease each year.
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How do you test for it?
There is no definitive test for Kawasaki disease. We diagnose based on the symptom criteria discussed above. There are, however, a few lab abnormalities that are typical of the disease. High platelet count in the second week is the most iconic, although it may be low initially. The white count and CRP (one indication of inflammation) are also both high, but signs of rheumatological disease (ANA, rheumatoid factor, etc) are negative. All bacterial cultures and titers are negative.
Echocardiograms are done regularly to evaluate the heart and coronary vessels. Since abnormalities can occur even several weeks after the disease, these will continue until the risk of abnormalities has passed, or as long as needed if there is something wrong.
What causes it?
We know that the symptoms are caused by the inflammation of the blood vessels, but we’re not quite sure what causes the inflammation. As with similar diseases we sometimes suspect that there was a previous illness with a bacteria or virus, but we’re not sure at this time.
How do you treat it?
The treatment depends on the stage of illness. In the first stage – usually the first 10-14 days when there is fever, the treatment is generally IVIG (intravenous immune globulin) and aspirin. As well as possibly shortening the time in the first stage, treatment started before the 10th day will significantly reduce the risk of coronary artery problems.
The treatment after that depends a lot on the state of the coronary arteries. Aspirin is continued as long as there is a risk of problems occurring, so for at least 6-12 months. If there are heart problems, then treatment continues as long as necessary, with added medication if needed.
Does it go away?
Kawasaki itself does go away. It may take a few weeks for the child’s energy to be back to normal, though, because of all the inflammation involved. Luckily 50% of coronary artery aneurysms get better within 2 years, and up to 80% within 5 years. However, the rest of them can be permanent problems.
Bottom line.
Kawasaki disease is a rare, but important cause of heart disease in children. If discovered and treated the risks can be improved.
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